Hallo all from sunny Sardinia.
On the past days I came across a well know problem in Minimoog, i.e. Overload lamp on and no sound.
So i decided to check the feedind on the vco board as all the fuses where ok. Between pins 1 and 2 i set + 10,1 Volts but, on the pins 2 and 3 there’s no way to reach more than only -6,9 Volts. The trimpot on the board number 3 looks like dead as I can’t see changes in voltage reading while twisting the resistor.
Any suggestion on this issue?
Mine is a Mini model D sn 2127 with all the boards marked R.A. MOOG
Thank you all!
Francesco
If both DC fuses (F1 and F2) are good (measured), then failure of the PSU section on board 3 is to be suspected.
Try removing boards and checking the voltages in between removals.
If one of the boards is shorted, the power supply should jump back to approx normal levels and you’ll know it’s one of the boards.
Yesterday after keeping the mini on for 4 hours it started working again, no issues, just pure sound… but after keeping it on for a couple hours again the lamp turned on…today I will chek the keyboard
I would suggest unplugging all the boards, one by one, and cleaning the edge contacts on each. It sounds like an intermitent electrical contact.
Hallo everybody,
after checking the whole instrument we realize that there is a problem with - 10V. Even feeding the instruments with a dummy current from an external device, the sense circuit immediately cut the tension down from 10 to 0.4 Volts this is due to a heavy load somewhere. My technician finally spot the problem on transistor q19 which is really working bad: in fact after removing it and feeding the machine with an external stabilized tension the mini worked fine. So now I have the board 3 on the laboratory 200 Km far away from home, on the next days I will receive the board with the new germanium transistor.
Hoping this experience will help somebody.
Next step will be a complete refitting of the keyboard.
cheers
Francesco