1970's Hammond LSI organ, no sound at all

[zerak456]

So I picked up this 1970's Hammond organ that I have been told is an LSI one, possibly of the Dolphin variety. It has no drawbars or tonewheel, just a set of "stops" with instrument names. When I got it the lower set of keys worked perfectly, but the upper set only had some instruments working. I took all of the easy to get to connectors out and cleaned them and that seemed to fix it back to entirely working. After a day of use it started doing a thing where no sound would come out on the first startup, but if you turned it off and back on again it would work fine. Now it does not produce any sound at all. The rest of the instrument turns on and works perfectly, the motors still spin the speaker drum around and all of that, but no sound at all. It doesn't even have the faint hum from the speakers at idle anymore.

Is there a common first thing to check or first diagnosis steps to take on these? I can provide pictures if needed, but an exact model number may be tough because all external stickers are missing.

[handyczech]

I think there is trouble in the power supply, which creates several different voltages for different parts of the organ. There are also a couple of fuses in the power supply, but if blown, there would be a deeper component level failure. I doubt there is any "ah ha" advice on this. ID the model, get a service manual as a download or Ebay, and start doing point to point voltage checks. That is, unless there is still a badly seated connector on the power supply. The model number is on a paper tag under the keyboard above your right knee, a number like 9200 or 9500 or 9700, could be Dolphin, Cougar or Maverick.