Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Hi everyone, this is my first post. i hope i get it right. teehee...

Anyway, i've got an old Lab Series L5 here from the late 70's. it went dead once so i gave it to a guy for a while to see if he could fix it. it came back with a new power supply and reverb driver pcb. It worked for a while but didn't sound near as good as it did before (not as much power, clipping at lower input, things like that.) after about 2 months or so it developed a much louder than usual hum. Then it just stopped amplifying any input, just a really loud hum, like if i were to hold onto my guitar cable and turn it up all the way. the compressor light just stays on and there's nothing i can do about it.

i was wondering if anyone could shed some light on my problem?

i have some basic electronics knowledge (graduated the basic electronics course at ft. gordon, georgia while training for 94F special electronics device repair)

i don't have a logic probe or an oscilloscope.
i do have a multi-meter, soldering iron, lots of time...

oh yea, i have schematics and wiring diagrams if it would help.

thanks in advance.

Edwards

Sounds to me like you have an issue with the PSU again, odds are the guy that rebuilt it for you used caps that are too small and/or a tranny that is too small.