Good morning,
I have a Fender style Reverb Tank, 4AB3C1A installed that replaced the original Marshall. Marshall mounted theirs inside the chassis because it has exposed voltage pins and no bell covers. Problem there was is was transmitting audio like an Omni direction antenna tower. I was getting a whole lot of bleed over.
This transformer has the bell covers but I’m still getting just a little bleed over into the P.I. & output jacks ( most likely from P.I.). I’ve been chasing down a ringing notes problem and perhaps this audio bleed over is the probable cause.
When I injected audio and ground the audio path at or before the output junction of V4A .022 / .002 / 1.8M, (see schematic) it completely shunts it. Anywhere after, like the grid of V4B or output to M.V., some small amount of audio is still getting through to the P.I. & output jacks. Not a lot, but it’s getting there. Also grounding on the other 002 coupling cap to the reverb V5 grid doesn’t do much at all.
If I disconnect the audio out of the reverb transformer to the reverb tank which is located still in the bag of the cabinet with audio grounding at V4B (anywhere after the 1.8M / 25p) then the audio bleed over disappears.
I mounted 2 RCA jacks to the chassis opposite of the power supply circuits about 1/2 apart and soldered in the coaxial cables to them internally. Coaxial is grounded to each respected input or output jack. The other side I just run regular audio RCA type cables to the tank.
When I remove the RCA jack that is going to the tank, send, with the audio grounded at V4B Master Vol, bleed over disappears. Removing the Return side drops lower but not completely out.
Reverb volume pots are zero, tried moving the grounding for the B+ node reverb from audio to mains ground and back, same for the P.I. / V4 nodes filter cap. That didn’t change anything.
Transformer is the TF-160
Thanks.
Topic: Reverb transformer grounding (Read 2645 times)