Dual 1219 problem - weak left channel output

Dual 1219 problem - weak left channel output

Hi Experts,

I have finally managed to get my 1219 going again, this time
with a new Shure M97xE.
It feeds into a Sony STRAV260 amplifier via RCA cables.

The right channel is working fine but the left one has a
very weak output. I swapped the
RCA connectors at the amplifier and output behavior also
swapped, so the problem is at the turntable.

Under the turntable there are four connector prongs beside
the muting switch. Two of the connectors are between one and
two inches above the others. The pair closest to the axis of
the turntable are attached to ends of the RCA cables. One of
the other prongs has nothing connected and the fourth prong
is connected to a ground lead that goes to the amplifier
case and to the shields of the two wires that carry the
output from the cartridge.

Without taking the arm off, it's not easy to see into that
area under the shell. Is it likely that there is a bad
contact there?

Comments appreciated.

RuF

Re: Dual 1219 problem - weak left channel output

RuF wrote:
> Hi Experts,
>
> I have finally managed to get my 1219 going again, this time with a new
> Shure M97xE.
> It feeds into a Sony STRAV260 amplifier via RCA cables.
>
> The right channel is working fine but the left one has a very weak
> output. I swapped the
> RCA connectors at the amplifier and output behavior also swapped, so the
> problem is at the turntable.
>
> Under the turntable there are four connector prongs beside the muting
> switch. Two of the connectors are between one and two inches above the
> others. The pair closest to the axis of the turntable are attached to
> ends of the RCA cables. One of the other prongs has nothing connected
> and the fourth prong is connected to a ground lead that goes to the
> amplifier case and to the shields of the two wires that carry the output
> from the cartridge.
>
> Without taking the arm off, it's not easy to see into that area under
> the shell. Is it likely that there is a bad contact there?
>
> Comments appreciated.
>
> RuF

RuF,

It is possible that the muting switch is causing the problem, but not
the first thing I'd suspect.

Dual used among the worst RCA cables in existence, so if you have not
already tried new ones, I would. The factory ones used crimped
connections, and the grounds commonly go bad causing hum and bad
connections.

There is a similar problem with the head shell leads These can be
resoldered, but you have to be VERY careful not to damage the head shell
contacts. Both the cartridge and head shell ends of the 4 wires are
suspect. You might want to consider a new head shell if they are still
available. A new old stock head shell may have the same problems as
your existing one, as the crimps have been around for many years.

The contacts in the arm itself, where the head shell connects can often
be corroded. Don't use a rough abrasive, as you'll remove the plating.
I'd start with a cotton swab moistened (not dripping) with a contact
cleaner. Do the head shell side of things too. I would then use a dry
q-tip to remove as much of the cleaner as possible. To be really
residue free, you could clean with alcohol.

Of course, first start by being sure that the head shell leads are all
going to the right places, and make sure the lugs going onto the
cartridge pins are snug. If they are loose, squeeze them GENTLY with
needle nose pliers or tweezers to tighten them up a bit. Be careful, if
you over-tighten them, then they won't fit the pins on the cartridge any
more. They can also break.

Lastly, are you sure that the new cartridge is good? If you have an
ohmmeter, then measure the left and right windings of the cartridge.
The readings should be similar. This needs to be done with the head
shell removed from the turntable, but the cartridge can still be mounted
in the head shell.

Regards,
Tim Schwartz
Bristol Electronics

Re: Dual 1219 problem - weak left channel output

Tim Schwartz wrote:
> RuF wrote:
>> Hi Experts,
>>
>> I have finally managed to get my 1219 going again, this time with a
>> new Shure M97xE.
>> It feeds into a Sony STRAV260 amplifier via RCA cables.
>>
>> The right channel is working fine but the left one has a very weak
>> output. I swapped the
>> RCA connectors at the amplifier and output behavior also swapped, so
>> the problem is at the turntable.
>>
>> Under the turntable there are four connector prongs beside the muting
>> switch. Two of the connectors are between one and two inches above the
>> others. The pair closest to the axis of the turntable are attached to
>> ends of the RCA cables. One of the other prongs has nothing connected
>> and the fourth prong is connected to a ground lead that goes to the
>> amplifier case and to the shields of the two wires that carry the
>> output from the cartridge.
>>
>> Without taking the arm off, it's not easy to see into that area under
>> the shell. Is it likely that there is a bad contact there?
>>
>> Comments appreciated.
>>
>> RuF
>
> RuF,
>
> It is possible that the muting switch is causing the problem, but
> not the first thing I'd suspect.
>
> Dual used among the worst RCA cables in existence, so if you have not
> already tried new ones, I would. The factory ones used crimped
> connections, and the grounds commonly go bad causing hum and bad
> connections.
>
> There is a similar problem with the head shell leads These can be
> resoldered, but you have to be VERY careful not to damage the head shell
> contacts. Both the cartridge and head shell ends of the 4 wires are
> suspect. You might want to consider a new head shell if they are still
> available. A new old stock head shell may have the same problems as
> your existing one, as the crimps have been around for many years.
>
> The contacts in the arm itself, where the head shell connects can often
> be corroded. Don't use a rough abrasive, as you'll remove the plating.
> I'd start with a cotton swab moistened (not dripping) with a contact
> cleaner. Do the head shell side of things too. I would then use a dry
> q-tip to remove as much of the cleaner as possible. To be really
> residue free, you could clean with alcohol.
>
> Of course, first start by being sure that the head shell leads are all
> going to the right places, and make sure the lugs going onto the
> cartridge pins are snug. If they are loose, squeeze them GENTLY with
> needle nose pliers or tweezers to tighten them up a bit. Be careful, if
> you over-tighten them, then they won't fit the pins on the cartridge any
> more. They can also break.
>
> Lastly, are you sure that the new cartridge is good? If you have an
> ohmmeter, then measure the left and right windings of the cartridge. The
> readings should be similar. This needs to be done with the head shell
> removed from the turntable, but the cartridge can still be mounted in
> the head shell.
>
> Regards,
> Tim Schwartz
> Bristol Electronics

Thanks Tim.

As you suggested I cleaned up all the contacts near the
pickup and then reinstalled
but it didn't do any good. Next I tweaked the contacts at
the rear of the shell and reinstalled.
That did the trick. Thanks again for your help.

RuF.

Re: Dual 1219 problem - weak left channel output

valhealey wrote:
> Tim Schwartz wrote:
>> RuF wrote:
>>> Hi Experts,
>>>
>>> I have finally managed to get my 1219 going again, this time with a
>>> new Shure M97xE.
>>> It feeds into a Sony STRAV260 amplifier via RCA cables.
>>>
>>> The right channel is working fine but the left one has a very weak
>>> output. I swapped the
>>> RCA connectors at the amplifier and output behavior also swapped, so
>>> the problem is at the turntable.
>>>
>>> Under the turntable there are four connector prongs beside the muting
>>> switch. Two of the connectors are between one and two inches above
>>> the others. The pair closest to the axis of the turntable are
>>> attached to ends of the RCA cables. One of the other prongs has
>>> nothing connected and the fourth prong is connected to a ground lead
>>> that goes to the amplifier case and to the shields of the two wires
>>> that carry the output from the cartridge.
>>>
>>> Without taking the arm off, it's not easy to see into that area under
>>> the shell. Is it likely that there is a bad contact there?
>>>
>>> Comments appreciated.
>>>
>>> RuF
>>
>> RuF,
>>
>> It is possible that the muting switch is causing the problem, but
>> not the first thing I'd suspect.
>>
>> Dual used among the worst RCA cables in existence, so if you have not
>> already tried new ones, I would. The factory ones used crimped
>> connections, and the grounds commonly go bad causing hum and bad
>> connections.
>>
>> There is a similar problem with the head shell leads These can be
>> resoldered, but you have to be VERY careful not to damage the head
>> shell contacts. Both the cartridge and head shell ends of the 4 wires
>> are suspect. You might want to consider a new head shell if they are
>> still available. A new old stock head shell may have the same
>> problems as your existing one, as the crimps have been around for many
>> years.
>>
>> The contacts in the arm itself, where the head shell connects can
>> often be corroded. Don't use a rough abrasive, as you'll remove the
>> plating. I'd start with a cotton swab moistened (not dripping) with a
>> contact cleaner. Do the head shell side of things too. I would then
>> use a dry q-tip to remove as much of the cleaner as possible. To be
>> really residue free, you could clean with alcohol.
>>
>> Of course, first start by being sure that the head shell leads are all
>> going to the right places, and make sure the lugs going onto the
>> cartridge pins are snug. If they are loose, squeeze them GENTLY with
>> needle nose pliers or tweezers to tighten them up a bit. Be careful,
>> if you over-tighten them, then they won't fit the pins on the
>> cartridge any more. They can also break.
>>
>> Lastly, are you sure that the new cartridge is good? If you have an
>> ohmmeter, then measure the left and right windings of the cartridge.
>> The readings should be similar. This needs to be done with the head
>> shell removed from the turntable, but the cartridge can still be
>> mounted in the head shell.
>>
>> Regards,
>> Tim Schwartz
>> Bristol Electronics
>
> Thanks Tim.
>
> As you suggested I cleaned up all the contacts near the pickup and then
> reinstalled
> but it didn't do any good. Next I tweaked the contacts at the rear of
> the shell and reinstalled.
> That did the trick. Thanks again for your help.
>
> RuF.

Seems like I spoke too soon. After copying 4 records to the
HD, the right channel
has now become the very weak one and the left is ok. I have
tried several different
records to make sure they were stereo and they were. I
tweaked the R and RG contacts
at the rear of the shell but that was no help.

I made some measurements across the 2 RCA connectors and
there was symmetry in
the resistances. For example, across the two skirts the
resistance was 0. From the black
prong to the red prong the resistance was 2.8 ohms. From the
black prong to the red skirt
and from the red prong to the black skirt the resistance was
1.35 ohms.

Comments appreciated

Re: Dual 1219 problem - weak left channel output

RuF wrote:
> valhealey wrote:
>> Tim Schwartz wrote:
>>> RuF wrote:
>>>> Hi Experts,
>>>>
>>>> I have finally managed to get my 1219 going again, this time with a
>>>> new Shure M97xE.
>>>> It feeds into a Sony STRAV260 amplifier via RCA cables.
>>>>
>>>> The right channel is working fine but the left one has a very weak
>>>> output. I swapped the
>>>> RCA connectors at the amplifier and output behavior also swapped, so
>>>> the problem is at the turntable.
>>>>
>>>> Under the turntable there are four connector prongs beside the
>>>> muting switch. Two of the connectors are between one and two inches
>>>> above the others. The pair closest to the axis of the turntable are
>>>> attached to ends of the RCA cables. One of the other prongs has
>>>> nothing connected and the fourth prong is connected to a ground lead
>>>> that goes to the amplifier case and to the shields of the two wires
>>>> that carry the output from the cartridge.
>>>>
>>>> Without taking the arm off, it's not easy to see into that area
>>>> under the shell. Is it likely that there is a bad contact there?
>>>>
>>>> Comments appreciated.
>>>>
>>>> RuF
>>>
>>> RuF,
>>>
>>> It is possible that the muting switch is causing the problem, but
>>> not the first thing I'd suspect.
>>>
>>> Dual used among the worst RCA cables in existence, so if you have not
>>> already tried new ones, I would. The factory ones used crimped
>>> connections, and the grounds commonly go bad causing hum and bad
>>> connections.
>>>
>>> There is a similar problem with the head shell leads These can be
>>> resoldered, but you have to be VERY careful not to damage the head
>>> shell contacts. Both the cartridge and head shell ends of the 4
>>> wires are suspect. You might want to consider a new head shell if
>>> they are still available. A new old stock head shell may have the
>>> same problems as your existing one, as the crimps have been around
>>> for many years.
>>>
>>> The contacts in the arm itself, where the head shell connects can
>>> often be corroded. Don't use a rough abrasive, as you'll remove the
>>> plating. I'd start with a cotton swab moistened (not dripping) with
>>> a contact cleaner. Do the head shell side of things too. I would
>>> then use a dry q-tip to remove as much of the cleaner as possible.
>>> To be really residue free, you could clean with alcohol.
>>>
>>> Of course, first start by being sure that the head shell leads are
>>> all going to the right places, and make sure the lugs going onto the
>>> cartridge pins are snug. If they are loose, squeeze them GENTLY with
>>> needle nose pliers or tweezers to tighten them up a bit. Be careful,
>>> if you over-tighten them, then they won't fit the pins on the
>>> cartridge any more. They can also break.
>>>
>>> Lastly, are you sure that the new cartridge is good? If you have an
>>> ohmmeter, then measure the left and right windings of the cartridge.
>>> The readings should be similar. This needs to be done with the head
>>> shell removed from the turntable, but the cartridge can still be
>>> mounted in the head shell.
>>>
>>> Regards,
>>> Tim Schwartz
>>> Bristol Electronics
>>
>> Thanks Tim.
>>
>> As you suggested I cleaned up all the contacts near the pickup and
>> then reinstalled
>> but it didn't do any good. Next I tweaked the contacts at the rear of
>> the shell and reinstalled.
>> That did the trick. Thanks again for your help.
>>
>> RuF.
>
> Seems like I spoke too soon. After copying 4 records to the HD, the
> right channel
> has now become the very weak one and the left is ok. I have tried
> several different
> records to make sure they were stereo and they were. I tweaked the R and
> RG contacts
> at the rear of the shell but that was no help.
>
> I made some measurements across the 2 RCA connectors and there was
> symmetry in
> the resistances. For example, across the two skirts the resistance was
> 0. From the black
> prong to the red prong the resistance was 2.8 ohms. From the black prong
> to the red skirt
> and from the red prong to the black skirt the resistance was 1.35 ohms.
>
> Comments appreciated

RuF,

If those measurements were made with the turntable in the off position,
then you are measuring what should be a near short across the cables.
If that is so, then you likely have a dirty muting switch or bad cables.
If that measurement was made with the unit on and the arm above the
record, then you've got the lowest resistance measurement I've ever
heard of on a cartridge.

Regards,
Tim Schwartz
Bristol Electronics

Re: Dual 1219 problem - weak left channel output

Tim Schwartz wrote:
> RuF wrote:
>> valhealey wrote:
>>> Tim Schwartz wrote:
>>>> RuF wrote:
>>>>> Hi Experts,
>>>>>
>>>>> I have finally managed to get my 1219 going again, this time with a
>>>>> new Shure M97xE.
>>>>> It feeds into a Sony STRAV260 amplifier via RCA cables.
>>>>>
>>>>> The right channel is working fine but the left one has a very weak
>>>>> output. I swapped the
>>>>> RCA connectors at the amplifier and output behavior also swapped,
>>>>> so the problem is at the turntable.
>>>>>
>>>>> Under the turntable there are four connector prongs beside the
>>>>> muting switch. Two of the connectors are between one and two inches
>>>>> above the others. The pair closest to the axis of the turntable are
>>>>> attached to ends of the RCA cables. One of the other prongs has
>>>>> nothing connected and the fourth prong is connected to a ground
>>>>> lead that goes to the amplifier case and to the shields of the two
>>>>> wires that carry the output from the cartridge.
>>>>>
>>>>> Without taking the arm off, it's not easy to see into that area
>>>>> under the shell. Is it likely that there is a bad contact there?
>>>>>
>>>>> Comments appreciated.
>>>>>
>>>>> RuF
>>>>
>>>> RuF,
>>>>
>>>> It is possible that the muting switch is causing the problem,
>>>> but not the first thing I'd suspect.
>>>>
>>>> Dual used among the worst RCA cables in existence, so if you have
>>>> not already tried new ones, I would. The factory ones used
>>>> crimped connections, and the grounds commonly go bad causing hum and
>>>> bad connections.
>>>>
>>>> There is a similar problem with the head shell leads These can be
>>>> resoldered, but you have to be VERY careful not to damage the head
>>>> shell contacts. Both the cartridge and head shell ends of the 4
>>>> wires are suspect. You might want to consider a new head shell if
>>>> they are still available. A new old stock head shell may have the
>>>> same problems as your existing one, as the crimps have been around
>>>> for many years.
>>>>
>>>> The contacts in the arm itself, where the head shell connects can
>>>> often be corroded. Don't use a rough abrasive, as you'll remove the
>>>> plating. I'd start with a cotton swab moistened (not dripping) with
>>>> a contact cleaner. Do the head shell side of things too. I would
>>>> then use a dry q-tip to remove as much of the cleaner as possible.
>>>> To be really residue free, you could clean with alcohol.
>>>>
>>>> Of course, first start by being sure that the head shell leads are
>>>> all going to the right places, and make sure the lugs going onto the
>>>> cartridge pins are snug. If they are loose, squeeze them GENTLY
>>>> with needle nose pliers or tweezers to tighten them up a bit. Be
>>>> careful, if you over-tighten them, then they won't fit the pins on
>>>> the cartridge any more. They can also break.
>>>>
>>>> Lastly, are you sure that the new cartridge is good? If you have an
>>>> ohmmeter, then measure the left and right windings of the cartridge.
>>>> The readings should be similar. This needs to be done with the head
>>>> shell removed from the turntable, but the cartridge can still be
>>>> mounted in the head shell.
>>>>
>>>> Regards,
>>>> Tim Schwartz
>>>> Bristol Electronics
>>>
>>> Thanks Tim.
>>>
>>> As you suggested I cleaned up all the contacts near the pickup and
>>> then reinstalled
>>> but it didn't do any good. Next I tweaked the contacts at the rear of
>>> the shell and reinstalled.
>>> That did the trick. Thanks again for your help.
>>>
>>> RuF.
>>
>> Seems like I spoke too soon. After copying 4 records to the HD, the
>> right channel
>> has now become the very weak one and the left is ok. I have tried
>> several different
>> records to make sure they were stereo and they were. I tweaked the R
>> and RG contacts
>> at the rear of the shell but that was no help.
>>
>> I made some measurements across the 2 RCA connectors and there was
>> symmetry in
>> the resistances. For example, across the two skirts the resistance was
>> 0. From the black
>> prong to the red prong the resistance was 2.8 ohms. From the black
>> prong to the red skirt
>> and from the red prong to the black skirt the resistance was 1.35 ohms.
>>
>> Comments appreciated
>
> RuF,
>
> If those measurements were made with the turntable in the off
> position, then you are measuring what should be a near short across the
> cables. If that is so, then you likely have a dirty muting switch or bad
> cables. If that measurement was made with the unit on and the arm above
> the record, then you've got the lowest resistance measurement I've ever
> heard of on a cartridge.
>
> Regards,
> Tim Schwartz
> Bristol Electronics

Thanks again Tim.

The measurements were made with the turntable in the off
position - arm on the rest. I
made the same measurements on the cartridge in the shell but
lying on a bench. The
measurements were very similar. There appeared to be a small
difference between the
resistances of the windings - one was a bit closer to 1.3
than 1.35 and the other was a
little on the other side of 1.35 - this was true for the
cables and cartridge in place and
for the cartridge in the shell on the bench. My ohmmeter has
rather course graduations
in that area.

Today I'll test with the arm over the turntable and will
check the muting switch and clean up the terminals and
anything else I can see in that area.

I'll be back soon. Your help is much appreciated.

Re: Dual 1219 problem - weak left channel output

Tim Schwartz wrote:
> RuF wrote:
>> valhealey wrote:
>>> Tim Schwartz wrote:
>>>> RuF wrote:
>>>>> Hi Experts,
>>>>>
>>>>> I have finally managed to get my 1219 going again, this time with a
>>>>> new Shure M97xE.
>>>>> It feeds into a Sony STRAV260 amplifier via RCA cables.
>>>>>
>>>>> The right channel is working fine but the left one has a very weak
>>>>> output. I swapped the
>>>>> RCA connectors at the amplifier and output behavior also swapped,
>>>>> so the problem is at the turntable.
>>>>>
>>>>> Under the turntable there are four connector prongs beside the
>>>>> muting switch. Two of the connectors are between one and two inches
>>>>> above the others. The pair closest to the axis of the turntable are
>>>>> attached to ends of the RCA cables. One of the other prongs has
>>>>> nothing connected and the fourth prong is connected to a ground
>>>>> lead that goes to the amplifier case and to the shields of the two
>>>>> wires that carry the output from the cartridge.
>>>>>
>>>>> Without taking the arm off, it's not easy to see into that area
>>>>> under the shell. Is it likely that there is a bad contact there?
>>>>>
>>>>> Comments appreciated.
>>>>>
>>>>> RuF
>>>>
>>>> RuF,
>>>>
>>>> It is possible that the muting switch is causing the problem,
>>>> but not the first thing I'd suspect.
>>>>
>>>> Dual used among the worst RCA cables in existence, so if you have
>>>> not already tried new ones, I would. The factory ones used
>>>> crimped connections, and the grounds commonly go bad causing hum and
>>>> bad connections.
>>>>
>>>> There is a similar problem with the head shell leads These can be
>>>> resoldered, but you have to be VERY careful not to damage the head
>>>> shell contacts. Both the cartridge and head shell ends of the 4
>>>> wires are suspect. You might want to consider a new head shell if
>>>> they are still available. A new old stock head shell may have the
>>>> same problems as your existing one, as the crimps have been around
>>>> for many years.
>>>>
>>>> The contacts in the arm itself, where the head shell connects can
>>>> often be corroded. Don't use a rough abrasive, as you'll remove the
>>>> plating. I'd start with a cotton swab moistened (not dripping) with
>>>> a contact cleaner. Do the head shell side of things too. I would
>>>> then use a dry q-tip to remove as much of the cleaner as possible.
>>>> To be really residue free, you could clean with alcohol.
>>>>
>>>> Of course, first start by being sure that the head shell leads are
>>>> all going to the right places, and make sure the lugs going onto the
>>>> cartridge pins are snug. If they are loose, squeeze them GENTLY
>>>> with needle nose pliers or tweezers to tighten them up a bit. Be
>>>> careful, if you over-tighten them, then they won't fit the pins on
>>>> the cartridge any more. They can also break.
>>>>
>>>> Lastly, are you sure that the new cartridge is good? If you have an
>>>> ohmmeter, then measure the left and right windings of the cartridge.
>>>> The readings should be similar. This needs to be done with the head
>>>> shell removed from the turntable, but the cartridge can still be
>>>> mounted in the head shell.
>>>>
>>>> Regards,
>>>> Tim Schwartz
>>>> Bristol Electronics
>>>
>>> Thanks Tim.
>>>
>>> As you suggested I cleaned up all the contacts near the pickup and
>>> then reinstalled
>>> but it didn't do any good. Next I tweaked the contacts at the rear of
>>> the shell and reinstalled.
>>> That did the trick. Thanks again for your help.
>>>
>>> RuF.
>>
>> Seems like I spoke too soon. After copying 4 records to the HD, the
>> right channel
>> has now become the very weak one and the left is ok. I have tried
>> several different
>> records to make sure they were stereo and they were. I tweaked the R
>> and RG contacts
>> at the rear of the shell but that was no help.
>>
>> I made some measurements across the 2 RCA connectors and there was
>> symmetry in
>> the resistances. For example, across the two skirts the resistance was
>> 0. From the black
>> prong to the red prong the resistance was 2.8 ohms. From the black
>> prong to the red skirt
>> and from the red prong to the black skirt the resistance was 1.35 ohms.
>>
>> Comments appreciated
>
> RuF,
>
> If those measurements were made with the turntable in the off
> position, then you are measuring what should be a near short across the
> cables. If that is so, then you likely have a dirty muting switch or bad
> cables. If that measurement was made with the unit on and the arm above
> the record, then you've got the lowest resistance measurement I've ever
> heard of on a cartridge.
>
> Regards,
> Tim Schwartz
> Bristol Electronics


Thanks again Tim. Your help is much appreciated.

This time the measurements were made with the pickup on the
record about
mid point in the tracks.

The results of the measurements were exactly the same as
before, which would
appear to suggest that there may be a problem with the mute
switch. The RCA
cables were installed a few months ago to replace the old
5-pin DIN plug and cable
and were soldered to the same connections that were used
previously. The original
ground cables from the turntable are still used and are
attached to the chassis
of the Sony amplifier. The ground from the arm wiring is
also attached to the same
wires. I guess I could replace the original ground cables,
if necessary.

Today I'll check the muting switch and clean up the
terminals and anything else I
can see in that area.

Re: Dual 1219 problem - weak left channel output

Tim Schwartz wrote:
> RuF wrote:
>> valhealey wrote:
>>> Tim Schwartz wrote:
>>>> RuF wrote:
>>>>> Hi Experts,
>>>>>
>>>>> I have finally managed to get my 1219 going again, this time with a
>>>>> new Shure M97xE.
>>>>> It feeds into a Sony STRAV260 amplifier via RCA cables.
>>>>>
>>>>> The right channel is working fine but the left one has a very weak
>>>>> output. I swapped the
>>>>> RCA connectors at the amplifier and output behavior also swapped,
>>>>> so the problem is at the turntable.
>>>>>
>>>>> Under the turntable there are four connector prongs beside the
>>>>> muting switch. Two of the connectors are between one and two inches
>>>>> above the others. The pair closest to the axis of the turntable are
>>>>> attached to ends of the RCA cables. One of the other prongs has
>>>>> nothing connected and the fourth prong is connected to a ground
>>>>> lead that goes to the amplifier case and to the shields of the two
>>>>> wires that carry the output from the cartridge.
>>>>>
>>>>> Without taking the arm off, it's not easy to see into that area
>>>>> under the shell. Is it likely that there is a bad contact there?
>>>>>
>>>>> Comments appreciated.
>>>>>
>>>>> RuF
>>>>
>>>> RuF,
>>>>
>>>> It is possible that the muting switch is causing the problem,
>>>> but not the first thing I'd suspect.
>>>>
>>>> Dual used among the worst RCA cables in existence, so if you have
>>>> not already tried new ones, I would. The factory ones used
>>>> crimped connections, and the grounds commonly go bad causing hum and
>>>> bad connections.
>>>>
>>>> There is a similar problem with the head shell leads These can be
>>>> resoldered, but you have to be VERY careful not to damage the head
>>>> shell contacts. Both the cartridge and head shell ends of the 4
>>>> wires are suspect. You might want to consider a new head shell if
>>>> they are still available. A new old stock head shell may have the
>>>> same problems as your existing one, as the crimps have been around
>>>> for many years.
>>>>
>>>> The contacts in the arm itself, where the head shell connects can
>>>> often be corroded. Don't use a rough abrasive, as you'll remove the
>>>> plating. I'd start with a cotton swab moistened (not dripping) with
>>>> a contact cleaner. Do the head shell side of things too. I would
>>>> then use a dry q-tip to remove as much of the cleaner as possible.
>>>> To be really residue free, you could clean with alcohol.
>>>>
>>>> Of course, first start by being sure that the head shell leads are
>>>> all going to the right places, and make sure the lugs going onto the
>>>> cartridge pins are snug. If they are loose, squeeze them GENTLY
>>>> with needle nose pliers or tweezers to tighten them up a bit. Be
>>>> careful, if you over-tighten them, then they won't fit the pins on
>>>> the cartridge any more. They can also break.
>>>>
>>>> Lastly, are you sure that the new cartridge is good? If you have an
>>>> ohmmeter, then measure the left and right windings of the cartridge.
>>>> The readings should be similar. This needs to be done with the head
>>>> shell removed from the turntable, but the cartridge can still be
>>>> mounted in the head shell.
>>>>
>>>> Regards,
>>>> Tim Schwartz
>>>> Bristol Electronics
>>>
>>> Thanks Tim.
>>>
>>> As you suggested I cleaned up all the contacts near the pickup and
>>> then reinstalled
>>> but it didn't do any good. Next I tweaked the contacts at the rear of
>>> the shell and reinstalled.
>>> That did the trick. Thanks again for your help.
>>>
>>> RuF.
>>
>> Seems like I spoke too soon. After copying 4 records to the HD, the
>> right channel
>> has now become the very weak one and the left is ok. I have tried
>> several different
>> records to make sure they were stereo and they were. I tweaked the R
>> and RG contacts
>> at the rear of the shell but that was no help.
>>
>> I made some measurements across the 2 RCA connectors and there was
>> symmetry in
>> the resistances. For example, across the two skirts the resistance was
>> 0. From the black
>> prong to the red prong the resistance was 2.8 ohms. From the black
>> prong to the red skirt
>> and from the red prong to the black skirt the resistance was 1.35 ohms.
>>
>> Comments appreciated
>
> RuF,
>
> If those measurements were made with the turntable in the off
> position, then you are measuring what should be a near short across the
> cables. If that is so, then you likely have a dirty muting switch or bad
> cables. If that measurement was made with the unit on and the arm above
> the record, then you've got the lowest resistance measurement I've ever
> heard of on a cartridge.
>
> Regards,
> Tim Schwartz
> Bristol Electronics

Thanks again Tim. Your help is much appreciated.

This time the measurements were made with the
pickup on the record about
mid point in the tracks.

The results of the measurements were exactly the
same as before, which would
appear to suggest that there may be a problem with
the mute switch. The RCA
cables were installed a few months ago to replace
the old 5-pin DIN plug and cable
and were soldered to the same connections that
were used previously. The original
ground cables from the turntable are still used
and are attached to the chassis
of the Sony amplifier. The ground from the arm
wiring is also attached to the same
wires. I guess I could replace the original ground
cables, if necessary.

Today I'll check the muting switch and clean up
the terminals and anything else I
can see in that area.

Re: Dual 1219 problem - weak left channel output

RuF wrote:

>> If those measurements were made with the turntable in the off
>> position, then you are measuring what should be a near short across
>> the cables. If that is so, then you likely have a dirty muting switch
>> or bad cables. If that measurement was made with the unit on and the
>> arm above the record, then you've got the lowest resistance
>> measurement I've ever heard of on a cartridge.
>>
>> Regards,
>> Tim Schwartz
>> Bristol Electronics
>
> Thanks again Tim. Your help is much appreciated.
>
> This time the measurements were made with the pickup on the record about
> mid point in the tracks.
>
> The results of the measurements were exactly the same as before, which
> would
> appear to suggest that there may be a problem with the mute switch. The
> RCA
> cables were installed a few months ago to replace the old 5-pin DIN plug
> and cable
> and were soldered to the same connections that were used previously. The
> original
> ground cables from the turntable are still used and are attached to the
> chassis
> of the Sony amplifier. The ground from the arm wiring is also attached
> to the same
> wires. I guess I could replace the original ground cables, if necessary.
>
> Today I'll check the muting switch and clean up the terminals and
> anything else I
> can see in that area.

I think you definitely should check that area. There should be a
difference in reading with the arm down.

Are you sure you're reading the correct scale on your ohm meter? I
couldn't remember typical DC resistances off the top of my head, so I
pulled out a few old carts and got out the meter. On an assortment of
Shure, Stanton and Pickering units (about five altogether), the readings
ran anywhere from 1.25 to 1.5 *KILO* ohms. However, before I looked
closely at the range indicator on my autoranging meter, I started to
wonder what Tim was referring to.

There's no way you could get any output at all if your cartridge was
shorted out, which is the appearance of the readings you report. Check
again.

OTOH, you should be reading a dead short with the mute switch closed.
Perhaps there's enough resistance in the wiring to give you a reading of
1.35 ohms--close enough--and the cart resistance is close to that
reading, but in KILO ohms, and you didn't notice the difference?

In the same drawer, which I've not pulled out in years, there are three
NOS (never used--no idea why I have them unless it was from my days as a
turntable setup tech in the 70's) Dual slide-in cartridge mounts. The
contacts on all of those are pretty nasty. IMO, it would take chemicals
or some serious elbow grease to make them serviceable. I'd pull yours
and make doubly sure that all the contacts, including the ones on the
cartridge terminals and the tonearm, are impeccably bright and shiny.
There's a lot of potential for contact resistance there.

jak

Re: Dual 1219 problem - weak left channel output

jakdedert wrote:
> RuF wrote:
>
>>> If those measurements were made with the turntable in the off
>>> position, then you are measuring what should be a near short across
>>> the cables. If that is so, then you likely have a dirty muting switch
>>> or bad cables. If that measurement was made with the unit on and the
>>> arm above the record, then you've got the lowest resistance
>>> measurement I've ever heard of on a cartridge.
>>>
>>> Regards,
>>> Tim Schwartz
>>> Bristol Electronics
>>
>> Thanks again Tim. Your help is much appreciated.
>>
>> This time the measurements were made with the pickup on the record about
>> mid point in the tracks.
>>
>> The results of the measurements were exactly the same as before, which
>> would
>> appear to suggest that there may be a problem with the mute switch.
>> The RCA
>> cables were installed a few months ago to replace the old 5-pin DIN
>> plug and cable
>> and were soldered to the same connections that were used previously.
>> The original
>> ground cables from the turntable are still used and are attached to
>> the chassis
>> of the Sony amplifier. The ground from the arm wiring is also attached
>> to the same
>> wires. I guess I could replace the original ground cables, if necessary.
>>
>> Today I'll check the muting switch and clean up the terminals and
>> anything else I
>> can see in that area.
>
> I think you definitely should check that area. There should be a
> difference in reading with the arm down.
>
> Are you sure you're reading the correct scale on your ohm meter? I
> couldn't remember typical DC resistances off the top of my head, so I
> pulled out a few old carts and got out the meter. On an assortment of
> Shure, Stanton and Pickering units (about five altogether), the readings
> ran anywhere from 1.25 to 1.5 *KILO* ohms. However, before I looked
> closely at the range indicator on my autoranging meter, I started to
> wonder what Tim was referring to.
>
> There's no way you could get any output at all if your cartridge was
> shorted out, which is the appearance of the readings you report. Check
> again.
>
> OTOH, you should be reading a dead short with the mute switch closed.
> Perhaps there's enough resistance in the wiring to give you a reading of
> 1.35 ohms--close enough--and the cart resistance is close to that
> reading, but in KILO ohms, and you didn't notice the difference?
>
> In the same drawer, which I've not pulled out in years, there are three
> NOS (never used--no idea why I have them unless it was from my days as a
> turntable setup tech in the 70's) Dual slide-in cartridge mounts. The
> contacts on all of those are pretty nasty. IMO, it would take chemicals
> or some serious elbow grease to make them serviceable. I'd pull yours
> and make doubly sure that all the contacts, including the ones on the
> cartridge terminals and the tonearm, are impeccably bright and shiny.
> There's a lot of potential for contact resistance there.
>
> jak

Thanks Jak.

I just completed an inspection and decided to
resolder all 4 contacts on the
RCA cables and the grounds, where they connect
into the mute switch area.
I couldn't tell very much about that switch, so I
put everything back together
again and both channels worked for about 15 mins
and then the right one died
way back to less than 10% of the left channel and
stayed there looking almost
dead - just an occasional tiny spurt.

In what seems to be the mute switch there is
little block - about 3/4" square and
about 3/8" wide made up of layers of plastic and
metal. It is into this block that
all 4 connections mentioned above are made. There
are also two sprung contacts
from it that lie against the large plastic wheel
with the small gears. This wheel is
concentric with the platter. Are those two
contacts the mute switch? How could
I disable it for a short while to test further.

The instrument I used was a GB Instruments GMT-12A
and the right end of the
scale has an omega. Then the numbers go 1,2,3 etc
.... up to 1K. Beyond that
is the infinity symbol.

The contacts at the end of the arm are shiny
silver but the ones at the end of the
shell, that make contact with them, are rather
dull. I'll try a little metal polish on
them soon and will let you know what happens.

Have a great evening :-)

Re: Dual 1219 problem - weak left channel output

jakdedert wrote:
> RuF wrote:
>
>>> If those measurements were made with the turntable in the off
>>> position, then you are measuring what should be a near short across
>>> the cables. If that is so, then you likely have a dirty muting switch
>>> or bad cables. If that measurement was made with the unit on and the
>>> arm above the record, then you've got the lowest resistance
>>> measurement I've ever heard of on a cartridge.
>>>
>>> Regards,
>>> Tim Schwartz
>>> Bristol Electronics
>>
>> Thanks again Tim. Your help is much appreciated.
>>
>> This time the measurements were made with the pickup on the record about
>> mid point in the tracks.
>>
>> The results of the measurements were exactly the same as before, which
>> would
>> appear to suggest that there may be a problem with the mute switch.
>> The RCA
>> cables were installed a few months ago to replace the old 5-pin DIN
>> plug and cable
>> and were soldered to the same connections that were used previously.
>> The original
>> ground cables from the turntable are still used and are attached to
>> the chassis
>> of the Sony amplifier. The ground from the arm wiring is also attached
>> to the same
>> wires. I guess I could replace the original ground cables, if necessary.
>>
>> Today I'll check the muting switch and clean up the terminals and
>> anything else I
>> can see in that area.
>
> I think you definitely should check that area. There should be a
> difference in reading with the arm down.
>
> Are you sure you're reading the correct scale on your ohm meter? I
> couldn't remember typical DC resistances off the top of my head, so I
> pulled out a few old carts and got out the meter. On an assortment of
> Shure, Stanton and Pickering units (about five altogether), the readings
> ran anywhere from 1.25 to 1.5 *KILO* ohms. However, before I looked
> closely at the range indicator on my autoranging meter, I started to
> wonder what Tim was referring to.
>
> There's no way you could get any output at all if your cartridge was
> shorted out, which is the appearance of the readings you report. Check
> again.
>
> OTOH, you should be reading a dead short with the mute switch closed.
> Perhaps there's enough resistance in the wiring to give you a reading of
> 1.35 ohms--close enough--and the cart resistance is close to that
> reading, but in KILO ohms, and you didn't notice the difference?
>
> In the same drawer, which I've not pulled out in years, there are three
> NOS (never used--no idea why I have them unless it was from my days as a
> turntable setup tech in the 70's) Dual slide-in cartridge mounts. The
> contacts on all of those are pretty nasty. IMO, it would take chemicals
> or some serious elbow grease to make them serviceable. I'd pull yours
> and make doubly sure that all the contacts, including the ones on the
> cartridge terminals and the tonearm, are impeccably bright and shiny.
> There's a lot of potential for contact resistance there.
>
> jak


Thanks Jak.

I just completed an inspection and decided to
resolder all 4 contacts on the
RCA cables and the grounds, where they connect
into the mute switch area.
I couldn't tell very much about that switch, so I
put everything back together
again and both channels worked for about 15 mins
and then the right one died
way back to less than 10% of the left channel and
stayed there looking almost
dead - just an occasional tiny spurt.

In what seems to be the mute switch there is
little block - about 3/4" square and
about 3/8" wide made up of layers of plastic and
metal. It is into this block that
all 4 connections mentioned above are made. There
are also two sprung contacts
from it that lie against the large plastic wheel
with the small gears. This wheel is
concentric with the platter. Are those two
contacts the mute switch? How could
I disable it for a short while to test further.

The instrument I used was a GB Instruments GMT-12A
and the right end of the
scale has an omega. Then the numbers go 1,2,3 etc
.... up to 1K. Beyond that
is the infinity symbol.

The contacts at the end of the arm are shiny
silver but the ones at the end of the
shell, that make contact with them, are rather
dull. I'll try a little metal polish on
them soon and will let you know what happens.

Have a great evening :-)

Re: Dual 1219 problem - weak left channel output

RuF wrote:
> jakdedert wrote:
>> RuF wrote:
>>
>>>> If those measurements were made with the turntable in the off
>>>> position, then you are measuring what should be a near short across
>>>> the cables. If that is so, then you likely have a dirty muting
>>>> switch or bad cables. If that measurement was made with the unit on
>>>> and the arm above the record, then you've got the lowest resistance
>>>> measurement I've ever heard of on a cartridge.
>>>>
>>>> Regards,
>>>> Tim Schwartz
>>>> Bristol Electronics
>>>
>>> Thanks again Tim. Your help is much appreciated.
>>>
>>> This time the measurements were made with the pickup on the record about
>>> mid point in the tracks.
>>>
>>> The results of the measurements were exactly the same as before,
>>> which would
>>> appear to suggest that there may be a problem with the mute switch.
>>> The RCA
>>> cables were installed a few months ago to replace the old 5-pin DIN
>>> plug and cable
>>> and were soldered to the same connections that were used previously.
>>> The original
>>> ground cables from the turntable are still used and are attached to
>>> the chassis
>>> of the Sony amplifier. The ground from the arm wiring is also
>>> attached to the same
>>> wires. I guess I could replace the original ground cables, if necessary.
>>>
>>> Today I'll check the muting switch and clean up the terminals and
>>> anything else I
>>> can see in that area.
>>
>> I think you definitely should check that area. There should be a
>> difference in reading with the arm down.
>>
>> Are you sure you're reading the correct scale on your ohm meter? I
>> couldn't remember typical DC resistances off the top of my head, so I
>> pulled out a few old carts and got out the meter. On an assortment of
>> Shure, Stanton and Pickering units (about five altogether), the
>> readings ran anywhere from 1.25 to 1.5 *KILO* ohms. However, before I
>> looked closely at the range indicator on my autoranging meter, I
>> started to wonder what Tim was referring to.
>>
>> There's no way you could get any output at all if your cartridge was
>> shorted out, which is the appearance of the readings you report.
>> Check again.
>>
>> OTOH, you should be reading a dead short with the mute switch closed.
>> Perhaps there's enough resistance in the wiring to give you a reading
>> of 1.35 ohms--close enough--and the cart resistance is close to that
>> reading, but in KILO ohms, and you didn't notice the difference?
>>
>> In the same drawer, which I've not pulled out in years, there are
>> three NOS (never used--no idea why I have them unless it was from my
>> days as a turntable setup tech in the 70's) Dual slide-in cartridge
>> mounts. The contacts on all of those are pretty nasty. IMO, it would
>> take chemicals or some serious elbow grease to make them serviceable.
>> I'd pull yours and make doubly sure that all the contacts, including
>> the ones on the cartridge terminals and the tonearm, are impeccably
>> bright and shiny. There's a lot of potential for contact resistance
>> there.
>>
>> jak
>
>
> Thanks Jak.
>
> I just completed an inspection and decided to resolder all 4 contacts on
> the
> RCA cables and the grounds, where they connect into the mute switch area.
> I couldn't tell very much about that switch, so I put everything back
> together
> again and both channels worked for about 15 mins and then the right one
> died
> way back to less than 10% of the left channel and stayed there looking
> almost
> dead - just an occasional tiny spurt.
>
> In what seems to be the mute switch there is little block - about 3/4"
> square and
> about 3/8" wide made up of layers of plastic and metal. It is into this
> block that
> all 4 connections mentioned above are made. There are also two sprung
> contacts
> from it that lie against the large plastic wheel with the small gears.
> This wheel is
> concentric with the platter. Are those two contacts the mute switch?
> How could
> I disable it for a short while to test further.
>
> The instrument I used was a GB Instruments GMT-12A and the right end of the
> scale has an omega. Then the numbers go 1,2,3 etc .... up to 1K. Beyond
> that
> is the infinity symbol.
>
> The contacts at the end of the arm are shiny silver but the ones at the
> end of the
> shell, that make contact with them, are rather dull. I'll try a little
> metal polish on
> them soon and will let you know what happens.
>
> Have a great evening :-)

I used metal polish to burnish the 4 contacts at
the rear of the shell
and then ttried to clean up the 4 mating contacts
at the front of the arm.
That was when I noticed that the contacts were
embedded in what
looked like a thin plastic sheet. While cleaning,
the plate kept moving up
and down. It was just pushed up into a slot and
was kept in place by
the shell. I pushed it all the way up and then
attached the cartridge.

On startup I had both channels working great.
Fingers crossed :-)

Thanks to all for the help.

RuF

Re: Dual 1219 problem - weak left channel output

RuF wrote:
> RuF wrote:
>> jakdedert wrote:
>>> RuF wrote:
>>>
>>>>> If those measurements were made with the turntable in the off
>>>>> position, then you are measuring what should be a near short across
>>>>> the cables. If that is so, then you likely have a dirty muting
>>>>> switch or bad cables. If that measurement was made with the unit
>>>>> on and the arm above the record, then you've got the lowest
>>>>> resistance measurement I've ever heard of on a cartridge.
>>>>>
>>>>> Regards,
>>>>> Tim Schwartz
>>>>> Bristol Electronics
>>>>
>>>> Thanks again Tim. Your help is much appreciated.
>>>>
>>>> This time the measurements were made with the pickup on the record
>>>> about
>>>> mid point in the tracks.
>>>>
>>>> The results of the measurements were exactly the same as before,
>>>> which would
>>>> appear to suggest that there may be a problem with the mute switch.
>>>> The RCA
>>>> cables were installed a few months ago to replace the old 5-pin DIN
>>>> plug and cable
>>>> and were soldered to the same connections that were used previously.
>>>> The original
>>>> ground cables from the turntable are still used and are attached to
>>>> the chassis
>>>> of the Sony amplifier. The ground from the arm wiring is also
>>>> attached to the same
>>>> wires. I guess I could replace the original ground cables, if
>>>> necessary.
>>>>
>>>> Today I'll check the muting switch and clean up the terminals and
>>>> anything else I
>>>> can see in that area.
>>>
>>> I think you definitely should check that area. There should be a
>>> difference in reading with the arm down.
>>>
>>> Are you sure you're reading the correct scale on your ohm meter? I
>>> couldn't remember typical DC resistances off the top of my head, so I
>>> pulled out a few old carts and got out the meter. On an assortment
>>> of Shure, Stanton and Pickering units (about five altogether), the
>>> readings ran anywhere from 1.25 to 1.5 *KILO* ohms. However, before
>>> I looked closely at the range indicator on my autoranging meter, I
>>> started to wonder what Tim was referring to.
>>>
>>> There's no way you could get any output at all if your cartridge was
>>> shorted out, which is the appearance of the readings you report.
>>> Check again.
>>>
>>> OTOH, you should be reading a dead short with the mute switch closed.
>>> Perhaps there's enough resistance in the wiring to give you a reading
>>> of 1.35 ohms--close enough--and the cart resistance is close to that
>>> reading, but in KILO ohms, and you didn't notice the difference?
>>>
>>> In the same drawer, which I've not pulled out in years, there are
>>> three NOS (never used--no idea why I have them unless it was from my
>>> days as a turntable setup tech in the 70's) Dual slide-in cartridge
>>> mounts. The contacts on all of those are pretty nasty. IMO, it
>>> would take chemicals or some serious elbow grease to make them
>>> serviceable. I'd pull yours and make doubly sure that all the
>>> contacts, including the ones on the cartridge terminals and the
>>> tonearm, are impeccably bright and shiny. There's a lot of potential
>>> for contact resistance there.
>>>
>>> jak
>>
>>
>> Thanks Jak.
>>
>> I just completed an inspection and decided to resolder all 4 contacts
>> on the
>> RCA cables and the grounds, where they connect into the mute switch area.
>> I couldn't tell very much about that switch, so I put everything back
>> together
>> again and both channels worked for about 15 mins and then the right
>> one died
>> way back to less than 10% of the left channel and stayed there looking
>> almost
>> dead - just an occasional tiny spurt.
>>
>> In what seems to be the mute switch there is little block - about 3/4"
>> square and
>> about 3/8" wide made up of layers of plastic and metal. It is into
>> this block that
>> all 4 connections mentioned above are made. There are also two sprung
>> contacts
>> from it that lie against the large plastic wheel with the small gears.
>> This wheel is
>> concentric with the platter. Are those two contacts the mute switch?
>> How could
>> I disable it for a short while to test further.
>>
>> The instrument I used was a GB Instruments GMT-12A and the right end
>> of the
>> scale has an omega. Then the numbers go 1,2,3 etc .... up to 1K.
>> Beyond that
>> is the infinity symbol.
>>
>> The contacts at the end of the arm are shiny silver but the ones at
>> the end of the
>> shell, that make contact with them, are rather dull. I'll try a little
>> metal polish on
>> them soon and will let you know what happens.
>>
>> Have a great evening :-)
>
> I used metal polish to burnish the 4 contacts at the rear of the shell
> and then ttried to clean up the 4 mating contacts at the front of the arm.
> That was when I noticed that the contacts were embedded in what
> looked like a thin plastic sheet. While cleaning, the plate kept moving up
> and down. It was just pushed up into a slot and was kept in place by
> the shell. I pushed it all the way up and then attached the cartridge.
>
> On startup I had both channels working great. Fingers crossed :-)
>
> Thanks to all for the help.
>
> RuF
>
>
Cool, I composed a lengthy tutorial last evening, but realized I wasn't
all that familiar with the innards of the Dual. I got sidetracked
trying to download a manual from this
< * w w w .vinylengine . com /news.shtml> site; but couldn't get
registered (confirming email not sent).

I was skeptical as to whether the muting switch was your problem, but
not familiar enough with the Dual guts to advise. From your post, it's
not directly actuated by moving the tonearm, which would make some of
the advice given spurious.

You have an analog meter, which negated my 'ranging' scenario somewhat;
unless you are unfamiliar with the function of the 'Range' switch on
your meter.

Glad you got it...hope it stays 'got'. I did think it was a headshell
contact issue....

jak

Re: Dual 1219 problem - weak left channel output

On Fri, 18 Apr 2008 08:03:07 -0500, jakdedert
<jakdedert@bellsouth . net > wrote:

>RuF wrote:
>> RuF wrote:
>>> jakdedert wrote:
>>>> RuF wrote:
>>>>
>>>>>> If those measurements were made with the turntable in the off
>>>>>> position, then you are measuring what should be a near short across
>>>>>> the cables. If that is so, then you likely have a dirty muting
>>>>>> switch or bad cables. If that measurement was made with the unit
>>>>>> on and the arm above the record, then you've got the lowest
>>>>>> resistance measurement I've ever heard of on a cartridge.
>>>>>>
>>>>>> Regards,
>>>>>> Tim Schwartz
>>>>>> Bristol Electronics
>>>>>
>>>>> Thanks again Tim. Your help is much appreciated.
>>>>>
>>>>> This time the measurements were made with the pickup on the record
>>>>> about
>>>>> mid point in the tracks.
>>>>>
>>>>> The results of the measurements were exactly the same as before,
>>>>> which would
>>>>> appear to suggest that there may be a problem with the mute switch.
>>>>> The RCA
>>>>> cables were installed a few months ago to replace the old 5-pin DIN
>>>>> plug and cable
>>>>> and were soldered to the same connections that were used previously.
>>>>> The original
>>>>> ground cables from the turntable are still used and are attached to
>>>>> the chassis
>>>>> of the Sony amplifier. The ground from the arm wiring is also
>>>>> attached to the same
>>>>> wires. I guess I could replace the original ground cables, if
>>>>> necessary.
>>>>>
>>>>> Today I'll check the muting switch and clean up the terminals and
>>>>> anything else I
>>>>> can see in that area.
>>>>
>>>> I think you definitely should check that area. There should be a
>>>> difference in reading with the arm down.
>>>>
>>>> Are you sure you're reading the correct scale on your ohm meter? I
>>>> couldn't remember typical DC resistances off the top of my head, so I
>>>> pulled out a few old carts and got out the meter. On an assortment
>>>> of Shure, Stanton and Pickering units (about five altogether), the
>>>> readings ran anywhere from 1.25 to 1.5 *KILO* ohms. However, before
>>>> I looked closely at the range indicator on my autoranging meter, I
>>>> started to wonder what Tim was referring to.
>>>>
>>>> There's no way you could get any output at all if your cartridge was
>>>> shorted out, which is the appearance of the readings you report.
>>>> Check again.
>>>>
>>>> OTOH, you should be reading a dead short with the mute switch closed.
>>>> Perhaps there's enough resistance in the wiring to give you a reading
>>>> of 1.35 ohms--close enough--and the cart resistance is close to that
>>>> reading, but in KILO ohms, and you didn't notice the difference?
>>>>
>>>> In the same drawer, which I've not pulled out in years, there are
>>>> three NOS (never used--no idea why I have them unless it was from my
>>>> days as a turntable setup tech in the 70's) Dual slide-in cartridge
>>>> mounts. The contacts on all of those are pretty nasty. IMO, it
>>>> would take chemicals or some serious elbow grease to make them
>>>> serviceable. I'd pull yours and make doubly sure that all the
>>>> contacts, including the ones on the cartridge terminals and the
>>>> tonearm, are impeccably bright and shiny. There's a lot of potential
>>>> for contact resistance there.
>>>>
>>>> jak
>>>
>>>
>>> Thanks Jak.
>>>
>>> I just completed an inspection and decided to resolder all 4 contacts
>>> on the
>>> RCA cables and the grounds, where they connect into the mute switch area.
>>> I couldn't tell very much about that switch, so I put everything back
>>> together
>>> again and both channels worked for about 15 mins and then the right
>>> one died
>>> way back to less than 10% of the left channel and stayed there looking
>>> almost
>>> dead - just an occasional tiny spurt.
>>>
>>> In what seems to be the mute switch there is little block - about 3/4"
>>> square and
>>> about 3/8" wide made up of layers of plastic and metal. It is into
>>> this block that
>>> all 4 connections mentioned above are made. There are also two sprung
>>> contacts
>>> from it that lie against the large plastic wheel with the small gears.
>>> This wheel is
>>> concentric with the platter. Are those two contacts the mute switch?
>>> How could
>>> I disable it for a short while to test further.
>>>
>>> The instrument I used was a GB Instruments GMT-12A and the right end
>>> of the
>>> scale has an omega. Then the numbers go 1,2,3 etc .... up to 1K.
>>> Beyond that
>>> is the infinity symbol.
>>>
>>> The contacts at the end of the arm are shiny silver but the ones at
>>> the end of the
>>> shell, that make contact with them, are rather dull. I'll try a little
>>> metal polish on
>>> them soon and will let you know what happens.
>>>
>>> Have a great evening :-)
>>
>> I used metal polish to burnish the 4 contacts at the rear of the shell
>> and then ttried to clean up the 4 mating contacts at the front of the arm.
>> That was when I noticed that the contacts were embedded in what
>> looked like a thin plastic sheet. While cleaning, the plate kept moving up
>> and down. It was just pushed up into a slot and was kept in place by
>> the shell. I pushed it all the way up and then attached the cartridge.
>>
>> On startup I had both channels working great. Fingers crossed :-)
>>
>> Thanks to all for the help.
>>
>> RuF
>>
>>
>Cool, I composed a lengthy tutorial last evening, but realized I wasn't
>all that familiar with the innards of the Dual. I got sidetracked
>trying to download a manual from this
>< * w w w .vinylengine . com /news.shtml> site; but couldn't get
>registered (confirming email not sent).
>
>I was skeptical as to whether the muting switch was your problem, but
>not familiar enough with the Dual guts to advise. From your post, it's
>not directly actuated by moving the tonearm, which would make some of
>the advice given spurious.
>
>You have an analog meter, which negated my 'ranging' scenario somewhat;
>unless you are unfamiliar with the function of the 'Range' switch on
>your meter.
>
>Glad you got it...hope it stays 'got'. I did think it was a headshell
>contact issue....
>
>jak


These Duals didn't have a mute switch problem unless the switch assy.
bracket's screws loosened up. There was a constant problem with the
headshell and arm contacts causing muted sound on either channel. As
other posters mentioned, the rca cables were a major failure point.
Another fairly common problem was the wires in the tone arm would go
intermittent. Replacing these isn't a project for the inexperienced.
Chuck

Re: Dual 1219 problem - weak left channel output

Tim Schwartz wrote:
> RuF wrote:
>> Hi Experts,
>>
>> I have finally managed to get my 1219 going again, this time with a
>> new Shure M97xE.
>> It feeds into a Sony STRAV260 amplifier via RCA cables.
>>
>> The right channel is working fine but the left one has a very weak
>> output. I swapped the
>> RCA connectors at the amplifier and output behavior also swapped, so
>> the problem is at the turntable.
>>
>> Under the turntable there are four connector prongs beside the muting
>> switch. Two of the connectors are between one and two inches above the
>> others. The pair closest to the axis of the turntable are attached to
>> ends of the RCA cables. One of the other prongs has nothing connected
>> and the fourth prong is connected to a ground lead that goes to the
>> amplifier case and to the shields of the two wires that carry the
>> output from the cartridge.
>>
>> Without taking the arm off, it's not easy to see into that area under
>> the shell. Is it likely that there is a bad contact there?
>>
>> Comments appreciated.
>>
>> RuF
>
> RuF,
>
> It is possible that the muting switch is causing the problem, but
> not the first thing I'd suspect.
>
> Dual used among the worst RCA cables in existence, so if you have not
> already tried new ones, I would. The factory ones used crimped
> connections, and the grounds commonly go bad causing hum and bad
> connections.
>
> There is a similar problem with the head shell leads These can be
> resoldered, but you have to be VERY careful not to damage the head shell
> contacts. Both the cartridge and head shell ends of the 4 wires are
> suspect. You might want to consider a new head shell if they are still
> available. A new old stock head shell may have the same problems as
> your existing one, as the crimps have been around for many years.
>
> The contacts in the arm itself, where the head shell connects can often
> be corroded. Don't use a rough abrasive, as you'll remove the plating.
> I'd start with a cotton swab moistened (not dripping) with a contact
> cleaner. Do the head shell side of things too. I would then use a dry
> q-tip to remove as much of the cleaner as possible. To be really
> residue free, you could clean with alcohol.
>
> Of course, first start by being sure that the head shell leads are all
> going to the right places, and make sure the lugs going onto the
> cartridge pins are snug. If they are loose, squeeze them GENTLY with
> needle nose pliers or tweezers to tighten them up a bit. Be careful, if
> you over-tighten them, then they won't fit the pins on the cartridge any
> more. They can also break.
>
> Lastly, are you sure that the new cartridge is good? If you have an
> ohmmeter, then measure the left and right windings of the cartridge. The
> readings should be similar. This needs to be done with the head shell
> removed from the turntable, but the cartridge can still be mounted in
> the head shell.
>
> Regards,
> Tim Schwartz
> Bristol Electronics

Thanks Tim.

As you suggested I cleaned up all the contacts near the
pickup and then reinstalled
but it didn't do any good. Next I tweaked the contacts at
the rear of the shell and reinstalled.
That did the trick. Thanks again for your help.

RuF.