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Input (MAINS) AC Fuse
Input (MAINS) AC Fuse
I've NEVER had to replace an input AC fuse on a piece of stereo gear,
but my old Kenwood KA-9X amp blew one the other day. It's a Toyo 6A
fuse (thats ALL it says on it..both ends: Toyo 6A) , and I suppose a
250VAC/6A fuse would work except I can't tell if it was a slo-blow or
fast blow cause there isn't much left. I'm surmising its a slo-blow,
but can anyone tell me what type is typically used for the input fuse
on solid state integrated stereo amps.
I've NEVER had to replace an input AC fuse on a piece of stereo gear,
but my old Kenwood KA-9X amp blew one the other day. It's a Toyo 6A
fuse (thats ALL it says on it..both ends: Toyo 6A) , and I suppose a
250VAC/6A fuse would work except I can't tell if it was a slo-blow or
fast blow cause there isn't much left. I'm surmising its a slo-blow,
but can anyone tell me what type is typically used for the input fuse
on solid state integrated stereo amps.
Re: Input (MAINS) AC Fuse
Chief_Billy@hotmail . com wrote:
> I've NEVER had to replace an input AC fuse on a piece of stereo gear,
> but my old Kenwood KA-9X amp blew one the other day. It's a Toyo 6A
> fuse (thats ALL it says on it..both ends: Toyo 6A) , and I suppose a
> 250VAC/6A fuse would work except I can't tell if it was a slo-blow or
> fast blow cause there isn't much left. I'm surmising its a slo-blow,
> but can anyone tell me what type is typically used for the input fuse
> on solid state integrated stereo amps.
It would be a 'slow blow' type. However it's most likely an IEC
(international) 20 x 5 mm type, in which case one of the fuse caps should
have the rating such as T5A where T means 'time delay' (slow blow to
ex-colonials) and 5A is the current rating.
Hmmm .. IEC fuses don't come in 6A ratings, it would be 6.3A. Anyway you
need to identify the right fuse size too (American or International).
Graham
Chief_Billy@hotmail . com wrote:
> I've NEVER had to replace an input AC fuse on a piece of stereo gear,
> but my old Kenwood KA-9X amp blew one the other day. It's a Toyo 6A
> fuse (thats ALL it says on it..both ends: Toyo 6A) , and I suppose a
> 250VAC/6A fuse would work except I can't tell if it was a slo-blow or
> fast blow cause there isn't much left. I'm surmising its a slo-blow,
> but can anyone tell me what type is typically used for the input fuse
> on solid state integrated stereo amps.
It would be a 'slow blow' type. However it's most likely an IEC
(international) 20 x 5 mm type, in which case one of the fuse caps should
have the rating such as T5A where T means 'time delay' (slow blow to
ex-colonials) and 5A is the current rating.
Hmmm .. IEC fuses don't come in 6A ratings, it would be 6.3A. Anyway you
need to identify the right fuse size too (American or International).
Graham
Re: Input (MAINS) AC Fuse
Start with a regular fuse and if it doesn't blow then you are probably fine.
If it does then try a slo-blow. Slo-blow are usually for equipment that has
high startup draw like motors. Because it delays you do not want to use one
unless you need to.
<Chief_Billy@hotmail . com > wrote in message
news:fvqno501na7@news3.newsguy . com ...
> I've NEVER had to replace an input AC fuse on a piece of stereo gear,
> but my old Kenwood KA-9X amp blew one the other day. It's a Toyo 6A
> fuse (thats ALL it says on it..both ends: Toyo 6A) , and I suppose a
> 250VAC/6A fuse would work except I can't tell if it was a slo-blow or
> fast blow cause there isn't much left. I'm surmising its a slo-blow,
> but can anyone tell me what type is typically used for the input fuse
> on solid state integrated stereo amps.
Start with a regular fuse and if it doesn't blow then you are probably fine.
If it does then try a slo-blow. Slo-blow are usually for equipment that has
high startup draw like motors. Because it delays you do not want to use one
unless you need to.
<Chief_Billy@hotmail . com > wrote in message
news:fvqno501na7@news3.newsguy . com ...
> I've NEVER had to replace an input AC fuse on a piece of stereo gear,
> but my old Kenwood KA-9X amp blew one the other day. It's a Toyo 6A
> fuse (thats ALL it says on it..both ends: Toyo 6A) , and I suppose a
> 250VAC/6A fuse would work except I can't tell if it was a slo-blow or
> fast blow cause there isn't much left. I'm surmising its a slo-blow,
> but can anyone tell me what type is typically used for the input fuse
> on solid state integrated stereo amps.
Re: Input (MAINS) AC Fuse
On May 6, 6:57 pm, Chief Bi...@hotmail . com wrote:
> I've NEVER had to replace an input AC fuse on a piece of stereo gear,
> but my old Kenwood KA-9X amp blew one the other day. It's a Toyo 6A
> fuse (thats ALL it says on it..both ends: Toyo 6A) , and I suppose a
> 250VAC/6A fuse would work except I can't tell if it was a slo-blow or
> fast blow cause there isn't much left. I'm surmising its a slo-blow,
> but can anyone tell me what type is typically used for the input fuse
> on solid state integrated stereo amps.
Slow Blow fuses will leave the ceramic rod inside the holder.
Dual-Element fuses will leave the small spring and clip inside the
holder.
Standard & Fast-Blow fuses will leave little or nothing remaining
inside the holder.
6A seems mighty close for a 700-watt @ 120V (5.8A) integrated
amplifier. What does it say on the fuse-holder? Mostly these things
typically use a dual-element or slow-blow as well. IF the fuse blew
because it is a 6A standard fuse, go ahead and replace it with a dual-
element and see what gives. If it blew for some other reason -beware.
But, before you willy-nilly replace the fuse and go back to sleep, you
need to do several things:
a) determine to the degree possible why the fuse blew. Anything
unusual happen? You may just be very lucky that a 6A standard fuse
held for so long anyway.
b) determine what the correct fuse should be. Look up a manual or
service literature or look at the fuse-holder for information. Note
that a fuse at 120V will carry twice the amperage rating than a fuse
at 240V for the same unit - not knowing where in the world you might
be. So, 6A at 240V is "too many". 6A at 120V is "barely enough" if a
standard type.
c) if you cannot do this, determine the actual current required by the
amplifier. You can do this to a degree by connecting it to a sensitive
ammeter and running it hard, or you can intuit from the nameplate
rating (in watts) to a reasonable degree. 700/120 = 5.83A, use 6A
(Dual-Element).
Note that the turn-on surge may be up to 3X the steady-state
requirement - and perhaps why it is that 6A fuse blew - all the
previous owner had was a standard fuse, and 6A was large enough to
handle the turn-on surge for a while.
Dual-Element fuses: Why do I harp? A DE Fuse acts like a slow-blow at
turn-on, handling the surge, but acts as a standard fuse after the
initial surge. So you get maximum protection of the equipment with
little risk of overloading. Note that a Slow-Blow fuse operates on a
function of overload/time. A small overload will be tolerated for a
very long time, a large overload for a much shorter time. That small
overload may be tolerated long enough to cause "other" parts to fail.
A dual-element fuse will tolerate a large load for a brief period, but
then fails at the set-point. Slow-Blow fuses (wire wound around a
ceramic core) protect nothing well.
Peter Wieck
Melrose Park, PA
On May 6, 6:57 pm, Chief Bi...@hotmail . com wrote:
> I've NEVER had to replace an input AC fuse on a piece of stereo gear,
> but my old Kenwood KA-9X amp blew one the other day. It's a Toyo 6A
> fuse (thats ALL it says on it..both ends: Toyo 6A) , and I suppose a
> 250VAC/6A fuse would work except I can't tell if it was a slo-blow or
> fast blow cause there isn't much left. I'm surmising its a slo-blow,
> but can anyone tell me what type is typically used for the input fuse
> on solid state integrated stereo amps.
Slow Blow fuses will leave the ceramic rod inside the holder.
Dual-Element fuses will leave the small spring and clip inside the
holder.
Standard & Fast-Blow fuses will leave little or nothing remaining
inside the holder.
6A seems mighty close for a 700-watt @ 120V (5.8A) integrated
amplifier. What does it say on the fuse-holder? Mostly these things
typically use a dual-element or slow-blow as well. IF the fuse blew
because it is a 6A standard fuse, go ahead and replace it with a dual-
element and see what gives. If it blew for some other reason -beware.
But, before you willy-nilly replace the fuse and go back to sleep, you
need to do several things:
a) determine to the degree possible why the fuse blew. Anything
unusual happen? You may just be very lucky that a 6A standard fuse
held for so long anyway.
b) determine what the correct fuse should be. Look up a manual or
service literature or look at the fuse-holder for information. Note
that a fuse at 120V will carry twice the amperage rating than a fuse
at 240V for the same unit - not knowing where in the world you might
be. So, 6A at 240V is "too many". 6A at 120V is "barely enough" if a
standard type.
c) if you cannot do this, determine the actual current required by the
amplifier. You can do this to a degree by connecting it to a sensitive
ammeter and running it hard, or you can intuit from the nameplate
rating (in watts) to a reasonable degree. 700/120 = 5.83A, use 6A
(Dual-Element).
Note that the turn-on surge may be up to 3X the steady-state
requirement - and perhaps why it is that 6A fuse blew - all the
previous owner had was a standard fuse, and 6A was large enough to
handle the turn-on surge for a while.
Dual-Element fuses: Why do I harp? A DE Fuse acts like a slow-blow at
turn-on, handling the surge, but acts as a standard fuse after the
initial surge. So you get maximum protection of the equipment with
little risk of overloading. Note that a Slow-Blow fuse operates on a
function of overload/time. A small overload will be tolerated for a
very long time, a large overload for a much shorter time. That small
overload may be tolerated long enough to cause "other" parts to fail.
A dual-element fuse will tolerate a large load for a brief period, but
then fails at the set-point. Slow-Blow fuses (wire wound around a
ceramic core) protect nothing well.
Peter Wieck
Melrose Park, PA
