Help - Smallbox Died

[SavageRiffer]

So I bought a Smallbox on Reverbv and it came in a few days ago. Everything was working perfectly fine. Then today, after playing about 30 minutes, it just stop making any sound at all. The power lights are all on, the tubes are all glowing evenly, there was not a single hiss or microphonic noise whatsoever. It just literally stopped making any sound all of the sudden. There was no pop or anything, just silence.

I unplugged my effects and plugged straight into the amp, still nothing. I replaced the fuse with an exact match, still the same. At this point, I'm not going to poke around the amp or anything as I'm inclined to send it back to the buyer. If it's not the power tubes, then what could be the problem? Is it something serious or will it be an expensive repair? If I end up getting stuck with this amp, how bad am I going to be screwed? Please advise.

 

[SavageRiffer]

OK, here's what I've done so far. I swapped the main fuse for a new one, still the same. Then I swapped all preamp and power tubes with brand new ones, still the same. Channel 1 does nothing. Channel 2 has a faint signal if I turn it all the way up - with some crackling. I tried a different speaker cable and different cab. So, it's not any of the tubes, it's not the fuse, and it's not the speaker or cables. I plugged my guitar straight into the return jack and was able to get sound on both channels. What does this mean?

 

[ChurchHill]

Well, if you're getting sound by plugging into the return jack, I'd think the problem would be somewhere between the effects loop and the input. Maybe a bad solder joint or a tube socket not making a good connection. If it's total silence when it's turned up load, I'd start at the effects loop and work toward the input, only because I'd think that if at least one gain stage was getting through, there'd be at least a little hiss.

Problem with this is that in order to check any of it out, you'd have to poke around in the amp at least visually, or with a wooden chop stick and one hand behind your back. A volt meter would be useful, too, just to see if there's a section that's not getting any power, if you don't know what the exact voltages are supposed to be. I once had a bad ground in an SLP that took me days to diagnose.

Anyway, just a few thoughts. If I was more familiar with the SB, I might have some more specific ideas, other than just back tracing until you find the bad component. Good luck! I've thought about picking one of these up, but haven't yet.