Solid State Guitar Amp Forum | DIY Guitar Amplifiers

I bought it used, tried it once quick before I packed up and moved, now it does nothing but hum, with or without a guitar plugged in. There's a slight smell emanating from the vent holes; smells like cooked components. Haven't had a chance to open it up yet. No explanation for a cause.

I fried a Crate Mini-stack yeeeeeeeeaaaaaaars ago by accidentally plugging the speaker outs into each other.  Smoke smell and buzz were the result.  I'll hazard a guess that it's the same thing here.  If you open it up, you'll most likely find a chip-amp handling the speaker output, and the smoke will have escaped.  First thing I'd do is replace the chipamp and the output capacitor, then work backwards from there if that doesn't cure it.  I couldn't find any schematics or specs to suss out what variety of chipamp is loaded in there, but talk around the 'net says contact Crate and they can advise you on that detail.

Are you handy with tools and a soldering iron?

schematic is in here:
https://supportloudtech.netx.net/loud-public/#/category/1

If it is the TDA2050 chip amp that is bad, they are no longer manufactured.

A valid substitute is the LM1875.
Drop in replacement.

I have attached the schematic.