Hey guys
Got a studio pro 112, started giving me some problems which sounded like only the pre-amp was working. If i cracked it, i could faintly hear the ghit over the speaker. sometimes a bash would correct it. I opened it up and tested shorts (if blown the short between the base and emmiter, right) on all transistors, but all seemed fine. The amp lay for quite a while and just jammed through my mixer, but im in a new band and need my amp. So when i started messing with it again, clean channel seems to be working fine, but when i switch the overdrive on, all i get an extra bit of buzz sounding like a earthing problem (which could well be since the circuitboard is outside the case), but no distortion.
Ive been lookin for circuit diagrams but can only find for sale, and im a bit outta cash, so new amp's also outta the question.. Was thinkin mayb a dry joint somewhere or those jacks which switch when u plug in ur fx loop for instance might not work properly?
Any help or suggestions would be appreciated.
Just an update..
It looks like someone worked on the amp before, tracks were lifted and filled with solder etc. Redid all the solder join and the lifted tracks replaced with solder. Same problems occur. Again the amp sounded like only the pre-amp works, but when in plugged the ghit straight into the fx loop return, the ghit was there (obviously with no volume/eq control), and when i plugged back into the high gain, the clean channel worked again. It seems like the fx loop return bypass switch in the plug itself makes good contact, but'll have to do that a million times to see if it's that. Also, the channel select has same result as described above.
Oh, there's also a rather prominent rythmic blipping sound, just faster than a second apart. These might still all be earthing, just assembling the thing again with propper earth etc to see what it's gonna do and at least use the clean channel for now.
Thanks again
Stomped - put the amp back together and all is perfect..? Don't like intermittant faults so if anyone still has an idea..