JCM800-2204 build issues

[fossilshark]

Ive almost got this p2p 2204 crammed into a 18w Marshall chassis. After replacing every shielded cable twice and reflowing every solder joint (who knew your iron could be too hot) I've but one small issue left.

When the master volume is turned down below 1 (goes away when turned up) there is a horrendous squealing that sounds related to the presence control/power lines. Is there any rules on what lines can go next to eachother? The amp is really small so ive ended up with B+ running next to the presence control input line (shielded) and things like this. Are there any rules of thumb?

Obviously the heater lines are as far away as possible but where do I ground the heater CT? Its currently grounded right to the chassis near B+ ground.

[sluckey]

schematic, pics. Heater CT is fine.

Disconnect NFB wire. Any better?

[fossilshark]

Disconnecting the negative feedback wire seemed to solve the issue except for s slight squeal thats changed (but not mitigated) by the tone stack. It also decreased the gain quite a bit but the volume is all there.

I know every connection looks suspect but I think i just have some wires routed incorrectly beyond that. All advice is greatly appreciated!

[fossilshark]

It is saying the pictures I took are too large, how can I post them?

[shooter]

open them in an image viewer, re-size <1Meg

[sluckey]

Disconnecting the negative feedback wire seemed to solve the issue except for s slight squeal thats changed (but not mitigated) by the tone stack. It also decreased the gain quite a bit but the volume is all there.

OK. Reconnect the NFB wire and swap the OT plate leads.

[fossilshark]

By Kirk's wah and Slash's hat, Sluckey nailed it. Swapping the plate leads seems to solve the issue. The only apparent gremlin left is a low weedwacker sound that is increased/deacreased by the gain pot. I suspect this is a power or ground issue. The broken wire is the NFB line and photos were taken before the plates were swapped.

The following images may be disturbing to some audiences.

[Latole]

Lead dress may need some work ; it may be a issue.
I don't like many solders, they could be good......?

[JB]

By Kirk's wah and Slash's hat, Sluckey nailed it. Swapping the plate leads seems to solve the issue. The only apparent gremlin left is a low weedwacker sound that is increased/deacreased by the gain pot. I suspect this is a power or ground issue. The broken wire is the NFB line and photos were taken before the plates were swapped.

The following images may be disturbing to some audiences.

Unrelated to your fault, are you fusing and switching the neutral side incoming from the IEC, live straight to the transformer?  And your fuse is soldered inline, bypassing that panel mount fuse holder, with the solder joint dangling in the breeze just above the ground pin of that cap? 

[sluckey]

For Latole...

The broken wire is the NFB line and photos were taken before the plates were swapped.

[Latole]

For Latole...

The broken wire is the NFB line and photos were taken before the plates were swapped.

Thank you.

[fossilshark]

yes the panel mount fuse holder broke and I need to replace that. could bad soldering cause the squeal coming from pre tone stack? Do I have any lines in bad spots? I will be making everything in it much neater now that there is sound.

[angelshred]

By Kirk's wah and Slash's hat, Sluckey nailed it. Swapping the plate leads seems to solve the issue. The only apparent gremlin left is a low weedwacker sound that is increased/deacreased by the gain pot. I suspect this is a power or ground issue. The broken wire is the NFB line and photos were taken before the plates were swapped.

The following images may be disturbing to some audiences.

Los cables de tela pueden ser un problema, no es buen aislante.

[Latole]

Los cables de tela pueden ser un problema, no es buen aislante.

Translation:
Cloth wires can be a problem, it is not a good insulator.