Tweet
Hello Organ Forum,
First off thank everyone for their contributions, there is an endless amount of knowledge stored here. I have been reading quite a few post as I am new to working on Hammond Organs. I have built a few guitar pedals, a single ended tube amp, and restored and modified a '69 fender Bassman.
I was recently gifted a Hammond Model M-3, Serial number 84470, that is not playable.
First the symptoms: The spinet now, after oiling with Hammond oil, spools up and runs quietly. However, as the amp warms up a loud hum/buzz starts. It is effected my the volume/expression pedal, the volume switch, and is changed in pitch and texture by flipping the percussion switches. It is also effected but the 4th drawbar from the left for the upper manual. Both manuals seem to work and, when the volume pedal is pushed forward, it seems that they have the correct tone and are changed by the draw bars. Flipping the other vibrato switches does not seem to have much effect on it. It is a pretty throaty buzz.
What I have tried: I pulled all the tubes out (which are new), sprayed deoxit in the tube sockets, and worked the tubes in and out several times. I sprayed deoxit on the drawbars and exercised them. I marked their position and exercised the percussion cut off control and well as the pedal cut off control. Looked over the wiring and connections to try and find any thing loose. I only found the two sets of brown and black wires coming from the run motor were crimped on the terminal switch but not soldered. I thought this was odd but could not find evidence that they were ever soldered. When I wiggled them while it was running, the run motor lost power and spun down. The noise was not effected. Once I bent them on the terminal strip, It started up and ran as it had. I tapped around on the caps, wires and tubes that are exposed looking for anything microphonic but could not perceive a change in the noise. I was also able to get the percussion switch cover up enough to pull out the felt, spray deoxit around each switch and exercise them. This did not seem to make any difference.
So this is were I am. I think I've tried all the easy, "you may get lucky" steps and I now I need some guidance. I have started to read into re-caping the tone generator. The one article discussed calibration once the caps were changed. I have also read some comments here that discussed trouble shooting by grounding difference points in the circuit. If someone could link me to a more in-depth discussion on this or explain it further I would be very grateful. Should I have the ground clipped to the amp chassis or the generator chassis? etc.
I thank anyone in advance for their time, patience, and knowledge.
-Jesse W. Martin
First off thank everyone for their contributions, there is an endless amount of knowledge stored here. I have been reading quite a few post as I am new to working on Hammond Organs. I have built a few guitar pedals, a single ended tube amp, and restored and modified a '69 fender Bassman.
I was recently gifted a Hammond Model M-3, Serial number 84470, that is not playable.
First the symptoms: The spinet now, after oiling with Hammond oil, spools up and runs quietly. However, as the amp warms up a loud hum/buzz starts. It is effected my the volume/expression pedal, the volume switch, and is changed in pitch and texture by flipping the percussion switches. It is also effected but the 4th drawbar from the left for the upper manual. Both manuals seem to work and, when the volume pedal is pushed forward, it seems that they have the correct tone and are changed by the draw bars. Flipping the other vibrato switches does not seem to have much effect on it. It is a pretty throaty buzz.
What I have tried: I pulled all the tubes out (which are new), sprayed deoxit in the tube sockets, and worked the tubes in and out several times. I sprayed deoxit on the drawbars and exercised them. I marked their position and exercised the percussion cut off control and well as the pedal cut off control. Looked over the wiring and connections to try and find any thing loose. I only found the two sets of brown and black wires coming from the run motor were crimped on the terminal switch but not soldered. I thought this was odd but could not find evidence that they were ever soldered. When I wiggled them while it was running, the run motor lost power and spun down. The noise was not effected. Once I bent them on the terminal strip, It started up and ran as it had. I tapped around on the caps, wires and tubes that are exposed looking for anything microphonic but could not perceive a change in the noise. I was also able to get the percussion switch cover up enough to pull out the felt, spray deoxit around each switch and exercise them. This did not seem to make any difference.
So this is were I am. I think I've tried all the easy, "you may get lucky" steps and I now I need some guidance. I have started to read into re-caping the tone generator. The one article discussed calibration once the caps were changed. I have also read some comments here that discussed trouble shooting by grounding difference points in the circuit. If someone could link me to a more in-depth discussion on this or explain it further I would be very grateful. Should I have the ground clipped to the amp chassis or the generator chassis? etc.
I thank anyone in advance for their time, patience, and knowledge.
-Jesse W. Martin
Comment