Hi all.
I’ve serviced a few different MM models in the last few years, but I have a 210 65 on the bench currently for a recap and service (please note the photo was taken before the recap), and I cannot get the tremolo to calibrate as per the service bulletin. The effect works, but the intensity knob does some whacky things. Between 1 and 3 is a very strong traditional style trem, then it kinda dies between 3 and 4, then from 4 up it’s a sort of doubled/tripled up tremolo that almost sounds like vibrato or a Leslie. Engaging the tremolo also seems to load down preamp output volume considerably (I could observe this on the scope whilst trying he calibration procedure, and turning the trem on and off with the foot switch).
Also, to get the effect to work at all, I need to have the trim pot turned full counterclockwise, which is where the bulletin tells you to start, not finish!
One more quirky thing, the schematic shows a 220K on the output of the trim pot. This amp has a 330K which looks factory.
I have good voltage at the trim pot (both inout and output), and I’ve measured most of the resistors in that area of the circuit. I think it’s safe to say the oscillator works (as the effect works). A partially failed 2n4091?
This amp is a consignment sale for a music shop I do a lot of work for, and I don’t want to sink too many hours into it, as then everyone loses their sale margins, but it would be nice to get it going properly.
