Hammond AO-28 distorted percussion

[ubxf]

I had a perfectly working AO-28 but everything on it was original caps, tubes everything. So i thought i would change the electrolytic caps and put a brand new set of tubes on it. After checking that all the voltages were close to the schematic i put it back in. Now it doesn't work any more. It passes audio and vibrato and percussion works but with percussion i have quite a few problems. The percussion on _off has a loud pop. With percussion in the low register it triggers very loud bursts. If i play a chord in the low register i get loud feedback. I thought i reversed the AX7 and AU7 by mistake but no, unless the tubes are mislabeled.
I put back in the old tubes but same problem. So it is definitely something i did. I changed again all 8 electrolytic but same thing unfortunately.
I will try another AO28 in there to make sure it is not a coincidence and something happened to the organ. IF anyone had a similar problem or any suggestions it would be great . Cheers

[David Anderson]

I have seen several people reinstall AO28s incorrectly in terms of the wiring harness, getting wires on the wrong terminals.

Other than that, all I can add is that I recently paid a professional to rebuild a carburetor for an old car I own because I knew that he knew what he was doing and that it would work when I reinstalled it.

[Drawbar Dave]

If you didn't take photographs when you disconnected the wiring harness, can you google pictures of an AO28 in situ to use as a reference? When people send me their preamps for rebuilding I always urge them to photograph and label the wiring to aid reinstalling.

[Sweet Pete]

Had a similar low feedback and fuzz when the perc cutoff was stuck 'wide open' once.
Reflowed cap solder connections I thought were good many times. One or the other,maybe both?
Cue "Don't Stop Believing"....you'll figure it out.Have you ever re-plumbed an AO28 with non 'multi' stage caps?
No? I'd have a good look there just in case.
Loud on/off pop means the 'amp' part of the circuit works! Feeding back through the wide open cutoff circuit somehow?
Do you have short decay or is it in 'paradise' mode?

[ubxf]

Thank you guys, yes i took pictures and labeled the wires before i took them out so i don't think that's the problem. I will check again though. I've done 3 AO28 before all with separate caps and never had a problem. This sounds like the amplification of the percussion is more than it should be that's why i thought i reversed AX and AU tubes. The decay seems normal, the overdrive is only for the lowest octave if i play single notes. If i play chords then i get the feedback. I agree i could have it done by a pro and i would if i was an organist. I'm just doing this as a fun hobby like some people would do puzzle. With the help of this great community i've learned a lot and the more i know the more i see how much i don't know. But i keep trying.

[ubxf]

So it turns out it was the perc cut off thanks Pete. All working fine now. Thanks