1957 Hammond C3. I only hear percussion!

[Guest]

Greetings! I recently found myself in a position to acquire a 1957 Hammond C3 with matching year Leslie 22H. Naturally when i was auditioning the duet everything sounded great with the exception of some dirty contacts and some audible leaking electrolytic capacitors. The long and short is that i paid $2000 CDN (about $12.75 US) for the pair in physically 'good' condition, pedals, bench included. At any rate, first thing i did when i got everything back to the shop was tear down the power amp in the Leslie and replace all electrolytic caps. I also found at least 2 of the non polarized caps that were dead so i went ahead and replaced all of the coupling / tone caps in the amplifier with some sweet new Jupiter Red Aston caps. Oh i should also mention that i used a direct replacement for all caps, including cap cans. I should also probably note that all electrolytic caps were installed in the correct orientation and that even the non polarized caps were oriented with the end foil in the most suitable direction. The power amp got a good once over including a complete re-tube so i decided to move over to the AO28 and give it the same treatment. Maybe a good time to mention that i'm not an organ wizard by any means, i just repair / build guitar tube amps as a hobby.

So after some testing i was thinking everything was going great. Shortly after startup I slowly lost all sound from the preamp with the exception of percussion. I have tried the old headphone trick on the G G outs and also only hear percussion at that point as well. Beyond the amplification parts of the Hammond / Leslie i am a total n00b.

Just a quick re-cap (pun intended), both the preamp and power amp have received a complete compliment of new tubes and electrolytic capacitors. The power amp received new tone caps where in the preamp did not and now the only sound the organ will produce is percussion.

Any advise or direction is greatly appreciated and i am open to critics on replacing old stock tone caps as well!

[Jaim]

Check out http://bentonelectronics.com/ - thanks George!

Normally percussion is played on the upper manual b preset. Any sound on the lower? There are 2 signal inputs (vib and non vib). Same result on both?

Check preamp term A and B with phones for sound. (Shielded cable and cover). After that refer to George's guide.

Jim

[KC9UDX]

Whenever I hear audio slowly disappearing and never coming back the first thing I think is open grid leak resistor.

[David Anderson]

Look at the preamp schematic as a block diagram. The percussion signal enters the signal chain at a different point from the main signal from the rest of the drawbars. There are two primary input channels to the preamp, vibrato and non-vibrato. You select the input channel via the switch tablets on the drawbar base. If you are not getting sound with vibrato tabs in either position, then both input channels are somehow disabled. Or perhaps the input signals are being interrupted or shorted before they get to the preamp. It's odd to lose both input channels.

[Sweet Pete]

Hey Eric,

Congrats on your aquisitions,that rig should sound fantastic! Now that you've changed components it is acting up.Totally normal.
It's a can of worms,there are no partial rebuilds on something 60 years old.
We have people on here that have written their first post after doing the work all the time.I have followed these stories and drawn my own conclusions.
My simple theory is,if it works already; don't mess with it! Always consult before doing anything.Manuals,other organ techs,Google Images.....never do the work first.

People that know me on here have heard my A100 and don't realize it!
It's old and could use a complete overhaul,but as it sits, sounds so good when operated by the right player....
I'm content to let it fail naturally,which could be a ways off the way it still starts and plays!
Every cap in it is original.They grew old together!Organ sounds fantastic!Over it's life it has never gone over a month without some use.
This A100 never 'sat around' and works like a charm!

I can solder and I can also make mistakes....like forgetting to pull out the B drawbars with percussion on and the upper B preset down/engaged?
Apologies if you had drawbars pulled,like I'm pulling your leg!
At least you know the perc works! That's a 'first post' regular around here. "My perc won't decay"

Welcome and cheers!
Pete