Peavey Windsor head has Very Loud Hum

[Coop]

Yep, If momma aint happy, Nobody is happy.........lol We've been married 23 years, and the wife still hasn't found a cure for my selective hearing.

Yes, I understand basic power supplies. I understand some and parts of most basic tube amp stuff, but I still need to connect, many more dots. I really enjoy learning and working on tube amps. Thanks for explaining "detection" . Very interesting. I appreciate your time and will gladly listen to whatever you have to say. I know you know your stuff. We can never learn too much.

I'll check all the area's that you have suggested, and get back to you tomorrow evening. I have to wake up at 5:30 am in the morning. I'll talk to you tomorrow afternoon. Thanks Again my friend.

[Coop]

Well, Still scratching my head. R26 is 47 ohm, and it measures right at 47 ohm, in circuit and out of circuit. You said R26 should read zero, because of ground connections, but it reads 47 ohm. Also reflowed solder joints here.

I also pulled and tested all components out of circuit, around the texture, presence, and resonance controls. All read good. Reflowed solder joints in that same area. Hummmmmm. I know I'm missing something simple. I know I'll find it sooner or later. I just hope it's sooner than later. lol... What should I do next? Thanks

[Enzo]

OK then, 47 ohms it is. I expected zero ohms from experience on other similarly grounded Peavey amps. I'll look into it, there still could be a missing grounding somewhere.

[Coop]

I noticed one of the spacers, that lift the PCB off the chassis, had some serious corrosion. So I took it off, sanded the spacer and chassis. Reassembled. Hoped that was the problem. No luck again. I feel the same as you, regarding the ground problem theroy. Let me know when you have any more suggestions. I'm at aloss. Much appreciated, Coop

[Enzo]

OK, hard to read the print, but it appears to me thatthe cold end of R26 serves the lowest B+ voltage returns, and they are grounded to chassis at the input jacks. The other end of R26 serves the middle grounds and should be grounded at the FX loop jacks.

Look at the front surface of the loop jack bodies - the surface that presses against the wall on the inside of the chassis. The jack barrel fits through teh hole in the wall, but there should be a tiny sharp point on the front of each jack to make electrical contact with the chassis. Is that present? One could throw in identical looking jacks that lack the tiny ground point and thus no more ground.


Or otherwise, you got 47 ohms across R26, measure each end to chassis and see which end is not grounded.

I don't know that this is your problem, but it is at least a direction to try.

[Coop]

Hey Enzo,
Yes the FX Loop jacks do have the tiny sharp points that you mentioned. So, I should buy two new jacks that don't have the ground tips?

As for R26, Both ends measure around 0.2 ohms, with the pcb fully installed and tightened down. But, when I took the PCB out to look at the Loop Jacks, I measured R26 again: One end of R26 measured 47 ohms. The other end measured 0.2 ohms. Not sure if this is of importance.

What do you think?

[Enzo]

No no no, I was concerned that someone had already replaced them with jacks missing the ground points. They are important to HAVE.

OK< so your grounds are then OK, in the chassis, which is where it matters, the two ends of the 47 ohm resistor are grounded, so it reads "shorted" wich is what we want.

The amp is unstable for some reason, and I have been looking around trying to find some simple thing for you to correct. Apparently it won't be something simple. This will be hard to diagnose from afar.

Contact Gene Ford at the factory and explain that your WIndsor appears to be oscillating at RF. See if he has some suggestions.