Can fuses go bad?

@10ht: All the JC1 fuses are slow blow type.

Pryso

Can you please tell me if the JC1 fuses are fast or slow blow?
Thank you.

Pryso:

Looks like one of your amps has the replacement. The new parts are larger and thicker (and black in color). The originals were arranged by two parallel pairs in series. They are all replaced by one single part (although I used two of the large parts in series in mine), so the traces for one pair are shorted.

If you have cracked or damaged ones, DO NOT POWER UP your amp and send it to Parasound immediately (or fix it yourself). Those damaged current limiters can catch fire and you do not want that.

I think Parasound should have recalled all the older amps. This is a dangerous safety issue that should not be left up to customers to discover on their own.

Many thanks Dhl. I popped the tops on both amps yesterday. I had replaced the blown fuse with a 10A slo-blo and that amp worked but I didn't leave it on long.

Looking inside it was just as you described. Two of the nickel sized green disk caps had exploded and a third was cracked in the damaged amp. Interestingly, the other amp has only one larger black disk cap (about the size of a quarter), one cap positioned jumpered, and the other two positions blank in place of the four green caps.

My amps are more than five years old. One failed after a year and my dealer sent it in under warranty. I don't have any paperwork from that so I don't even know which amp was repaired. From your comments I suspect it was the one which now has the single large black disk cap.

With your advice I'll contact Parasound tomorrow.

I would also check those surge current limiters, esp if you have an older production JC1.

They are on the AC input board and look like large green capacitors. The older design has four of them clustered together. These can "current hog" and burn out with sparks and smoke. The newer design replaces four of them with two much higher rated ones.

On one of my JC1s I was seeing arcing in the vicinity of this board when turning on my amp. It was sometimes accompanied by a burning smell and smoke. When I took the board out and looked, one of the surge current limiters was literally blown out in the middle with chunks of encapsulant missing. I am lucky they did not catch fire.

These limit the surge current going the power supply capacitors and come under a lot of stress on start up. The parts in the older design were underrated for the large amount of capacitance in the JC1 power supply.

Tony in the CS/Tech Support group at Parasound will send you free replacements or you can send the amp to them for replacement. If you have the older ones, get these replaced ASAP.

Ceramic fuses have a powder in them, maybe thats what smelled.

Yes, fuses do fail. They're creating some resistance to the current and expanding and contracting with the resultant heat. You shouldn't be worried unless the replacement also blows.