Hello,
Our house took a lightning surge last weekend, and I lost output in my
home theater subwoofer (Onkyo SKW-150). I took off the back panel and
found that one of two 5x20mm 4A 250V fuses was definitely blown. The other
may be (I'm not showing any continuity with an ohmeter). I have been
unable to find any 4A 250V fuses in the Dayton OH area. The closest I can
find is 4A 125V at Radio Shack. I tried a pair 3.15A 250V fuses, but they
appear to have blown as soon as the subwoofer was plugged in (one quick
"pop" from the speaker, then nothing)

At this point, I don't know if the fuses are the only problem, or if
something else got fried. Nothing looks toasted, and there was no "hot
electronics" smell, so I'm hopeful. I'd kind of like to know before I go
online and order some fuses (and pay more in shipping than the fuses cost)
and find that that wasn't the only problem, Would it be safe to try the 4A
125V fuses just to see if the rest of the circuitry is OK?

BTW, I'm assuming these are fast-blow fuses. They have no markings other
than amp/volt ratings and UL, etc. marks.

Thanks
Ray Maple

Ray Maple wrote:

Hello,
Our house took a lightning surge last weekend, and I lost output in my
home theater subwoofer (Onkyo SKW-150). I took off the back panel and
found that one of two 5x20mm 4A 250V fuses was definitely blown. The other
may be (I'm not showing any continuity with an ohmeter). I have been
unable to find any 4A 250V fuses in the Dayton OH area. The closest I can
find is 4A 125V at Radio Shack. I tried a pair 3.15A 250V fuses, but they
appear to have blown as soon as the subwoofer was plugged in (one quick
"pop" from the speaker, then nothing)

At this point, I don't know if the fuses are the only problem, or if
something else got fried. Nothing looks toasted, and there was no "hot
electronics" smell, so I'm hopeful. I'd kind of like to know before I go
online and order some fuses (and pay more in shipping than the fuses cost)
and find that that wasn't the only problem, Would it be safe to try the 4A
125V fuses just to see if the rest of the circuitry is OK?

BTW, I'm assuming these are fast-blow fuses. They have no markings other
than amp/volt ratings and UL, etc. marks.

The 250V rating sugggests that they are fuses to the international IEC specs
rather than any US spec. The fact that they are 5x20mm nails it.

Don't know how Radio Shack manange to source 125V 5x20mm fuses.

Fuses to the IEC spec should have a prefix letter indicating e.g. F ( fast blow
) or T ( slow blow ) - there is apparently IIRC also an M ( medium blow ) fuse
too but I've never seen one. Also FF ( but you're unlikely ever to see those ).

So look for something like T4A or F4A.

You don't say if the 3.15A fuses you fitted were fast or slow so there's little
that can be deduced from your initial attemopts at a fix.


Graham

"Pooh Bear" wrote in message

Ray Maple wrote:

Hello,
Our house took a lightning surge last weekend, and I lost output
in my home theater subwoofer (Onkyo SKW-150). I took off the back
panel and found that one of two 5x20mm 4A 250V fuses was definitely
blown. The other may be (I'm not showing any continuity with an
ohmeter). I have been unable to find any 4A 250V fuses in the
Dayton OH area. The closest I can find is 4A 125V at Radio Shack.
I tried a pair 3.15A 250V fuses, but they appear to have blown as
soon as the subwoofer was plugged in (one quick "pop" from the
speaker, then nothing)

It doesn't sound good.

IME most equipment isn't so marginally designed that the turn-on surge would
instantly take out a power line fuse, just because it is a little
undersized.

The slow-blow versus not-slow-blow issue could be more significant. Check
the original blown fuses and see if there are any coil-shaped structures
left in them. If so, they were slow blow and should be replaced with
comparable parts.

"Ray Maple" wrote in message
...
Hello,
Our house took a lightning surge last weekend, and I lost output in my
home theater subwoofer (Onkyo SKW-150). I took off the back panel and
found that one of two 5x20mm 4A 250V fuses was definitely blown. The
other
may be (I'm not showing any continuity with an ohmeter). I have been
unable to find any 4A 250V fuses in the Dayton OH area. The closest I can
find is 4A 125V at Radio Shack. I tried a pair 3.15A 250V fuses, but they
appear to have blown as soon as the subwoofer was plugged in (one quick
"pop" from the speaker, then nothing)

At this point, I don't know if the fuses are the only problem, or if
something else got fried. Nothing looks toasted, and there was no "hot
electronics" smell, so I'm hopeful. I'd kind of like to know before I go
online and order some fuses (and pay more in shipping than the fuses cost)
and find that that wasn't the only problem, Would it be safe to try the
4A
125V fuses just to see if the rest of the circuitry is OK?

BTW, I'm assuming these are fast-blow fuses. They have no markings other
than amp/volt ratings and UL, etc. marks.

Thanks
Ray Maple



Likelihood is that something shorted in the sub is blowing the fuse. Bad
output transistors or IC, shorted power supply rectifier(s), etc.

Mark Z.

"Arny Krueger" wrote in
:

"Pooh Bear" wrote in message

It doesn't sound good.

IME most equipment isn't so marginally designed that the turn-on surge
would instantly take out a power line fuse, just because it is a
little undersized.

The slow-blow versus not-slow-blow issue could be more significant.
Check the original blown fuses and see if there are any coil-shaped
structures left in them. If so, they were slow blow and should be
replaced with comparable parts.



The 3.15A fuses were fast blow. I haven't found any prefix/suffix markings
on the original fuses to indicate fast or slow blow. They are glass fuses
with a fine wire coil wrapped around a thin insulating core.

Ray

Ray Maple wrote:

"Arny Krueger" wrote in
:

"Pooh Bear" wrote in message

It doesn't sound good.

IME most equipment isn't so marginally designed that the turn-on surge
would instantly take out a power line fuse, just because it is a
little undersized.

The slow-blow versus not-slow-blow issue could be more significant.
Check the original blown fuses and see if there are any coil-shaped
structures left in them. If so, they were slow blow and should be
replaced with comparable parts.


The 3.15A fuses were fast blow.

OK

I haven't found any prefix/suffix markings
on the original fuses to indicate fast or slow blow. They are glass fuses
with a fine wire coil wrapped around a thin insulating core.

That's typically the kind of construction used for slow blow fuses.

This may be your problem - not for sure - but maybe.

Suggest you acquire some T4A fuses.

http://www.mouser.com/?handler=data....Ne=130&N=50413

Mouser Part #: 504-GDC-4A Page 369
Mfr. Part #: BK/GDC-4A
Mfr: Cooper/Bussmann
Category: Fuses
Description: Bussmann 5mm x 20mm Glass Standard Time Delay Fuses 4A 250V 5X20MM



Graham

Ray Maple wrote in
:

"Arny Krueger" wrote in
:

"Pooh Bear" wrote in message

It doesn't sound good.

IME most equipment isn't so marginally designed that the turn-on
surge would instantly take out a power line fuse, just because it is
a little undersized.

The slow-blow versus not-slow-blow issue could be more significant.
Check the original blown fuses and see if there are any coil-shaped
structures left in them. If so, they were slow blow and should be
replaced with comparable parts.



The 3.15A fuses were fast blow. I haven't found any prefix/suffix
markings on the original fuses to indicate fast or slow blow. They are
glass fuses with a fine wire coil wrapped around a thin insulating
core.

Ray


Well, as predicted, the news isn't good. Installed some slow-blow 4A 250V
fuses, plugged it in, and got about a half second of hum follwed by
silence. Opened it back up and both fuses were toast. Looks like there is
something seriously wrong with the amp. I guess I should feel lucky. The
reciever was plugged into the same outlet. It at least appears to be fine.
Now the question is, do I fix it, or just get a new sub?

Thanks for the advice.

Ray

"Ray Maple" wrote in message
...
Ray Maple wrote in
:

"Arny Krueger" wrote in
:

"Pooh Bear" wrote in message

It doesn't sound good.

IME most equipment isn't so marginally designed that the turn-on
surge would instantly take out a power line fuse, just because it is
a little undersized.

The slow-blow versus not-slow-blow issue could be more significant.
Check the original blown fuses and see if there are any coil-shaped
structures left in them. If so, they were slow blow and should be
replaced with comparable parts.



The 3.15A fuses were fast blow. I haven't found any prefix/suffix
markings on the original fuses to indicate fast or slow blow. They are
glass fuses with a fine wire coil wrapped around a thin insulating
core.

Ray


Well, as predicted, the news isn't good. Installed some slow-blow 4A 250V
fuses, plugged it in, and got about a half second of hum follwed by
silence. Opened it back up and both fuses were toast. Looks like there
is
something seriously wrong with the amp. I guess I should feel lucky. The
reciever was plugged into the same outlet. It at least appears to be
fine.
Now the question is, do I fix it, or just get a new sub?

Thanks for the advice.

Ray

How old is it? Maybe could be fixed under warranty. Technically, any damage
caused by external sources wouldn't be covered, but as a practical matter,
output IC's go bad all the time for various reasons. Unless there were some
blackened foil traces or some other visible damage not related to any
manufacturing defect, the warranty servicer would just treat it as any other
warranty repair.

Mark Z.
(Authorized Onkyo service)