Hammond C3 Percussion Troubleshooting

[jphilli81]

Hello all,

This will be my first post on the forum. I'm looking for some insights about a peculiarity with my C3's percussion channel. The organ has had a difficult existence and I am rehabbing it. When the percussion channel is engaged at normal, I lose signal from the tones not associated with the percussion circuit. Basically I lose the low tones. They do return when switched to soft, at least in part. It should also be known that I swapped out the switch assembly for one from an M3 due to significant oxidation in the box. I was very diligent in making sure the lines were correctly reconnected, although I could have made a mistake, this was an issue before the swap. The amp was retubed with NOS tubes and had all electrolytics replaced including cans.

I'm thinking there could be an issue with the switches in the preset. It appears that the non-associated tones (1,2,3,6,7,8) bypass the percussion circuit regardless of it being engaged. I'm hoping someone has had some experience with this problem. Thanks in advance for your thoughts.

-Joe

[geoelectro]

Welcome Joe!
When the percussion is set to normal, the drawbar level is intentionally reduced by design. This is to accentuate the percussion signal. Although it is normal, many who don't care for it have added a jumper in the matching transformer to bypass the reduction.

geo

[jphilli81]

Geo,

Thank you for the answer. I see it now. I guess its a good day when your problem turns out to be not a problem, but an uneducated state. Would that mean the 3.9M between the secondary of the matching transformer and ground could be adjusted lower to get a more balanced mix, serving as the jumper?

-Joe

[geoelectro]

Yes. A short across it defeats the volume drop completely.
Geo

[jphilli81]

Thank you for your knowledge.