How badly have I damaged my amp

winter_reverb

thanks, I can't remember what went wrong last time but it wasn't the transformer and this just seems to be the same problem again. It has broken a few times now:

1) right after I got it (second hand from eBay), I think this was my fault, I hooked the amp to a speaker using a cheap coupler that didn't connect reliably so the speaker wasn't connected so severe mismatch

2) almost immediately after getting it repaired it broke again. This time it was while connecting pedals, I touched a jack, typical touching jack noise then silence. The people who repaired it the first time said the problem was unrelated to the first fault but were kind enough to fix it for free as it was so soon after they had fixed it before.

3) the time when I posted this thread. Possibly due to the Ohms mismatch but also when I was messing around with pedal connections

4) tonight after thinking it was fine, again whilst connecting pedals.

Seems to be a pattern in that when I am messing around with pedal connections with the master volume maxed thats when I break it. Should I not be doing this? I assumed it was ok because the actual volume is low, and the high master/low gain settings are whats recommended in the manual, and although touching unplugged cable jacks is a nasty noise surely it isn't worse than an extreme distortion or other loud sound the amp should be able to handle?

Makes me wonder if I just got a dud. Think I will get it fixed but it the problem reoccurs it is time to look for a new amp

ICBM

You shouldn't really be making and breaking connections with the amp fully on. Put it on standby, that's what it's for.

The reason it may be more dangerous than simply turning the amp up loud is because you could be allowing or triggering the amp into self-oscillation outside the audio range, which you won't hear but is very bad for it.

That said, most well-designed amps don't do this, and *should* be OK with that sort of treatment. It's just not a good practice really.

It's less likely to be caused by impedance mismatching or poor quality speaker cable (unless it's actually faulty), although combined with loud pops and buzzing it could be a factor.

If you have another fuse, try one more time with no power valves in. Leave the amp on for a while and flip the standby on and off a few times. If the fuse doesn't blow, it's either a power valve fault (even if they're new) or something in the OT-speaker circuit, most likely.

I have heard that these aren't the most robust amps, but apart from the minor fault on the 15 and this very dead 40, I haven't seen any problems personally. And they do sound good...