help with fuses on a Sunn Concert Bass

[OurLastMango]

hi everyone! I'm new here, but I could still really use some help. After 7 years of struggle, I have finally joined the Sunn family! I recently purchased a '75 Sunn Concert Bass head (silver front with only 5 knobs) and I love it! The problem is, when I went to play it recently, it wouldn't start up. the capacitors had just been replaced before I bought it, which makes me believe that it is a blown fuse. The problem is, I can't find anywhere that can tell me what fuse is used in this amp. Does anyone have any knowledge on this?? I desperately want my baby to work again! Also, if I should post this somewhere else, just let me know and I'll do so Thanks!

[loudthud]

Chances are the Concert Bass does not have a fuse, it was originally equipped with a circuit breaker. It may have a fuse if at some point in the past the circuit breaker failed and was replaced with a fuse.

40 year old vintage amplifiers aren't for everybody. They breakdown frequently and require repairs by people that know what they are doing. Sometimes they require parts that are hard to get or very expensive. If you intend to play a vintage amp once a week, you need to be real close friends with someone that can keep it going and be prepared to pay the expense.

[Isaac]

According to a schematic I looked at, it also had a thermal  cutout in series with the fuse. So if the power is out, that's another possibility.

[radiatedradiation]

I am having the same problem with mine that I just got So, what does it mean if the circuit breaker was triggered and now it won't turn on anymore for me after pushing it back in? I was playing on a 6 ohm Sunn cabinet so it is probably all my fault.

[Isaac]

There's nothing wrong with playing through a 6 ohm cabinet. Concert series amps can power anything down to 4 ohms. Higher impedances will lower the power output, but won't damage the amp.

So, if the circuit breaker opened, then the amp was drawing too much current. My first guess would be that it's a problem in the power supply or the power amp. On old amps, the power supply filter caps can start leaking, drawing excess current. That's where I'd start, if I were working on the amp. But it sounds to me as though you aren't an amp technician, so you should probably take it to someone who is.