Back to square one... success! Dumb mistake

[LeeMo]

Have a great time at the "Bisquit" , The weather promises to hold.


Lee

[Randy Magee]

Have a great time at the "Bisquit" , The weather promises to hold.


Lee

Thanks Lee! I may have to haul this darn Express to Tupelo to see if you can sort it out...

[Picker]

I don't see any pictures in either of the threads. Do you have any you can post?

[Structo]

Did this amp ever work correctly?

If not then I would suspect a faulty component.

I have had bad pots cause all kinds of weird symptoms.

Also, be sure to check the obvious things like your speaker cable.

I had a speaker cable that went bad in between the time I changed some stuff inside the amp.
Plugged it back in and I had zero output.
Thought my OT was sacked!

Turned out the $3.00 Marshall speaker cable had a break in it.
I was just about ready to order a new OT when I checked it.
I threw that damned thing as far as I could, then picked it up and put it in the garbage.

Many times we skip over the simple stuff because we think it has to be a complex problem.

Check the simple stuff first.

[dartanion]

I went back to your photos and it doesn't look like your ground buss on the pots is grounded. This is a problem for sure if indeed not grounded.

[guitarsnguns04]

I thought the same dartanion...take a jumper wire with alligator clips on both ends...attach one end to the chassis and you can check all your ground point in a minute by clipping on them one at a time...If its a ground issue you will find it quick this way. Good Luck

[M Fowler]

Yes it doesn't appear the buss is grounded in the picture.

[sliberty]

While I also usually ground one end of the bus, it certainly is not true that the bus isn't grounded. It is grounded through the pots to the chassis (unless he used those isolating bushings). I'd be surprised if the lack of an "additional" path to ground was the culpret here. In fact, I have always wondered why this obvious ground loop didn't cause problems. But of course it doesn't - the design works. Just not confident that it is a significant design feature though.

[T Wilcox]

On the TW the buss is grounded through the pots to chassis right?
Atleast on mine I used Alpha pots and they are grounded to chassis. Are there other brands of pots that may not connect rear of pot to the front where they mount?

Edit: Sliberty beat me. I would suggest metering that bus bar to chassis anyways to be sure if the OP hasn't already

Todd

[T Wilcox]

Looking at the pic posted above V1 pins 3 and 8 do not appear to be properly connected/soldered.
Also I'd check wire connections at the turrets as well. It can take a little longer to heat them up enough to make a good solder connection.

Todd

[M Fowler]

If you don't wrap the leads around the turrets and solder well you can get a loss that way. Also, wrapping the leads around the socket pins as well.

[Colossal]

Is the input jack grounded? I've enclosed a photo comparing Francesca to Randy's build...

[M Fowler]

Well I am guessing that is a star washer not an insulator but we will see what Randy says when he gets back from R&R

[Randy Magee]

I'm back from the Biscuit... what a great festival!

To answer some of your questions...

1) The buss is not grounded, but neither is Francesca... the ground through the pot cases checks with the DMM...

2) There is no isolation washer on the input jack...

3) Speakers and cables work fine on other amps, so that is eliminated.

Someone mentioned a bad pot... I suppose that is possible one was damaged with the heat to solder to the pot cases, that's something I have to check.

I also re-soldered all the connections on the tube sockets after crimping the leads on all the wires after all the scolding from many people

[marcoloco961]

It's not scolding Randy, it is just real common for people to hesitate to re-flow a solder joint that "looks good". Many times they fight looking for a larger problem when a few minutes spent re-flowing a few connections finally solves the problem.

I will have to second the chance that a pot could be damaged. I have had a bad pot cause the symptoms you are describing. I have never had good luck soldering to the back of the pots, so I just use a lock washer with a tab soldered to it and solder the bus to the tabs. I had some PEC pots recently that had such small clearance between the back and the inside components that I ruined the pot by while bending over the tab. It barely dented the back of the pot, but totally destroyed it. Might be a good place to start. The heat needed to flow the solder to the back could have damaged the pot.