Hi to all
I got a Mesa Studio Preamp in need of help.
The preamp needed a cap change, most of the signal path capacitors were open or shorted, so I proceed to replace them.
After all, I powered the unit, and the clean is working fine, but the odd cames when the lead channel is engaged.
The lead works, but the lead master volume and the fat option doesnt work.
So in order to see if the switching system works(this one uses ldrs) I unsoldered the vactrols and soldered a led in place of the led side of the vactrol.
here comes the strange thing:
the lead master and the fat option leds lights up in clean channel mode, and not in the lead channel mode as they should.
I've tryed to manually short the cell side of the ldr when the lead channel is engaged, and everythin works as it should.
The vactrols are fine, I've tested them, and just to be sure, I've made two by using leds and photocells, and they works just fine.
I've attached a copy of the schematics, just dont consider the mods in blue.
Any suggestions or idea?
Thanks in advance
Mike
I got a Mesa Studio Preamp in need of help.
The preamp needed a cap change, most of the signal path capacitors were open or shorted, so I proceed to replace them.
After all, I powered the unit, and the clean is working fine, but the odd cames when the lead channel is engaged.
The lead works, but the lead master volume and the fat option doesnt work.
So in order to see if the switching system works(this one uses ldrs) I unsoldered the vactrols and soldered a led in place of the led side of the vactrol.
here comes the strange thing:
the lead master and the fat option leds lights up in clean channel mode, and not in the lead channel mode as they should.
I've tryed to manually short the cell side of the ldr when the lead channel is engaged, and everythin works as it should.
The vactrols are fine, I've tested them, and just to be sure, I've made two by using leds and photocells, and they works just fine.
I've attached a copy of the schematics, just dont consider the mods in blue.
Any suggestions or idea?
Thanks in advance
Mike
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