HV CT Ground

[Phil_S]

Looking at those pictures, I'm not liking the way the OT signal wires look so close to the filament wires. See if you can arc those away from each other.

I really don't understand all of those wires on the OT. It looks odd to me. Where is the primary on that OT?

[C Moore]

The primary on the OT are the black and white wire.

[C Moore]

Looking at those pictures, I'm not liking the way the OT signal wires look so close to the filament wires. See if you can arc those away from each other.

I really don't understand all of those wires on the OT. It looks odd to me. Where is the primary on that OT?

The pics are deceiving. There is quite a bit of distance between heater and OT wires. However, I have chop-sticked them around/further apart with no relief.
Thanks for the observation......

[tictac]

Looks like you've got grounds all over the place...

The wire soldered to the back of the tone control and volume; what purpose does that serve? Looks like you made a ground loop there.

The incomming safety/chassis ground looks as though it's connected to a different peice of metal than the part of the chassis your using as a ground plane. It really should be connected to the same...

Just for kicks you might want to check all of your grounds with an Ohm Meter set on low ohms setting to make sure your ground connections are good

TT

[C Moore]

Looks like you've got grounds all over the place...

The wire soldered to the back of the tone control and volume; what purpose does that serve? Looks like you made a ground loop there.

The incomming safety/chassis ground looks as though it's connected to a different peice of metal than the part of the chassis your using as a ground plane. It really should be connected to the same...

Just for kicks you might want to check all of your grounds with an Ohm Meter set on low ohms setting to make sure your ground connections are good

TT

Yeah....it might look that way.
I moved grounds all over the place trying to see if I could get rid of the hum.
The mains ground ohms out just as low where it is in the pictures as anywhere else, and does not effect my noise issue. It is on the same plane as all the other components, it is just bent at 90 degrees.
The back of the pots was just another test for noise, as suggested by some other members, it is no longer connected to anything.
I do not know what else to try at this point. I realize you guys are at a disadvantage, you do not have the amp in front of you. But I honestly am at the limits of my experience. I am not sure if I even have another PT that I can substitute for this one. Maybe I should take a look at what I have laying around that might work.?
Or is this still most likely a lead dress/lay-out issue. Maybe I am still just missing something simple........
Thank You

[tictac]

Here's a tip that may help you quickly isolate the source of your noise.

Make this noise finder probe in the drawing.

You can clip one end to ground and while the amp is on touch different points in the circuit to see if you can make the noise go away. If you find a location where the noise goes away when you touch it you've isolated the noise source, or at least the section that's picking up the noise...

Hope this helps...

TT

[C Moore]

10-4
I will give that a go.
Thanks

[C Moore]

http://www.webphix.com/schematic%20heav ... 12_6v6.pdf
Not exactly sure of the theory behind this tool I made.....
When I touch it to Pin 2 on V1 the hum is about 80% better. So that is the plate, plate resistor, and coupling cap. What does this tell me exactly.? I have tried different tubes, but that has not helped.
Thanks

[tictac]

You've got something going on in the 1st stage of your preamp.

From the looks of your pictures you may have something going on with the way you've wired your input jacks.

What I would do is rewire the the grid connection (pin 1) of the 1st preamp tube.

First disconnect everything from pin 1 next solder a 1Meg resistor directly onto pin 1. The other end of that resistor should have a good solid ground connection to the chassis, DON'T use the mounting ring of the tube but a solder terminal bolted to the chassis with a clean metal to metal connection.

Next, get your 47k or 56k resistor, connect one end to pin 1 and the other end to the input jack. What you end up with is one input jack connected to the input of V1.

If you still have noise on pin 2 then you've got a bad tube socket, a bad input jack, a bad plate resistor or a bad tube...

TT

[tictac]

The way this tool works is you are using the probe to make an AC ground where ever you touch the probe.

If there is noise on the part of the circuit your probing it will be sent to ground so you won't hear it anymore...

TT

[C Moore]

Nothing definitive yet. I am working on replacing that first tube socket. Gotta drill out some rivets, tight quarters......will report later today.
Thanks

[C Moore]

I am at a complete loss. I have tried everything I can think of including:
Replace tube socket
Replace in-put jack
Change/un-ground speaker jack
Change/remove NFB
Play with/check all the grounds to everything.
I keep thinking this must be from something I have done, or a lay-out issue. But I cannot find what is causing this. With that "probe" tool, I can follow the hum from Pin 2 of V1, and then into and out of the volume pot. But there is nothing in that area that I have been able to change or relocate that will fix this.
Thank You

[Hellhammer]

So how does your grounding scheme look at the moment? Are the grounds still spread out like that over the chassis or have you redone it? Use only one point of the chassis as ground, and use a buss or star grounding to tie them all together. Don't know if it would help but...

[C Moore]

Yeah.....I could try a "star Ground", but I am not sure the best place to locate that. One problem I have is the lay-out of the amp is necessarily all over the place. I have tried to ground stuff to their corresponding tubes/cathodes, but my circuits had to be located on both sides of the chassis, and the pots are way far from the rest of the amp.
I definitely can give the star a try. Thanks.

[C Moore]

Sometimes I worry too much.....but I care about what I am doing, and you guys always seem to go to such great lengths to make things "right". I ran a ground buss of 14 AWG for all the preamp ground connections, including the filtering. The power supply pretty much took care of itself. Proximity dictated all the grounds just kind of fell into the right place. I used jumper wires to test for the best ground locale for my pots. Where i had them was as good as any.
I buttoned this up, plugged into our living room power that is on a dedicated circuit and this amp is as quiet as any Black Face Fender. I am real happy with it now. Thanks for all of your help.....AGAIN.
I Appreciate It