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That was probably galaxiex's board! ;)

Aux 1 is switchable to pre or post fader with the MON button directly under the aux 1 level control of each channel. In one position, you'll also need to have the fader up to get signal out of the...

I'm starting to wonder if there is even a problem. Playing a guitar in close proximity to a cranked amp is often going to cause feedback. Is that what we have here? Is the feedback only when you stop...

Normally, I wouldn't suggest this simply because the problem only appears to be on one channel of the amp. But, since it's a new build and gain structure is different on each channel (and since it's...

The shield isn't plastic. It's actually a conductive shield around the center conductor. That said, I looked at your pic, and those wires are indeed shielded. You can see the shields soldered to...

https://www.youtube.com/watch?v=HPfOOBAOPcI

Edit: The one thing I do different is run the strings through the holes and f-hole before tying them to the parts. I find it easier to fish them through.

The easiest way to apply signal would be to just get a 1/4" plug and connect your leads to the plug. That also opens the shorting part of the input jack.

On the preamp tubes: If it were not...

The parametric on this amp is basically 2 parts.

The first is knobs 6 & 7. Knob 7 adjusts the frequency of the filter and 6 adjusts the gain at that selected frequency. In my opinion, the best way...

1) Yes, you can safely run the amp without a load. In fact, you should until you can power it up on the limiter without issue. Also, before you hook up a load/speaker, verify that there is no DC...

Agree and I'll add. Often tubes are microphonic in one position and not another. In other words and for example, a tube that might be microphonic in V1 position may be just fine in the V2 position. I...

https://www.sunnysidecorp.com/product.php?p=t&b=s&n=72416

Schematic here:

https://www.thetubestore.com/lib/thetubestore/schematics/Peavey/Peavey-XXX-Schematic.pdf

You may have an open HT fuse. Check F1. Sadly these days, new tubes does not always mean...

You can measure AC on the rectifier side of C8 and C9 to verify AC is getting to the rectifier without having to shotgun the caps.

Semi-related story: Your tests remind me of a shop I worked at in the late 80's. Attached to our shop was a car bay where they installed car stereos. They'd bring us all the old crappy factory...

I agree with your point of view regarding the shunt method. What I meant was the method you describe measuring the OT resistances. I inadvertently used the wrong terminology. Apologies.

FWIW: As a matter of course, when I pop the hood on a Hot Rod Deville, Deluxe, etc., I automatically resolder the output tube pins. It's a common enough problem to just take care of it- even if...

^^^^^^ That! Standby would remove B+, not bias V. I suspect you might have an intermittent connection in your bias supply circuit- maybe even the pot itself. I would leave the tubes out and monitor...

Was the hum there before the tube change? Did the old tubes work- no hum? If one or more of the old tubes was bad, you could have open screen resistor(s) or some other problem. I'd check pin 4 of all...

^^^^^ Yes. That. Also check any grounds soldered to the brass grounding plate in that area (if it has the plate). They can crack loose sometimes and cause intermittent problems.

I hid my desktop icons and used this wallpaper for a while. It really messes with people.
...

There are voltages marked on the schematic for much of the circuit. How do yours compare? Do you find any major discrepancies?

You betcha. :thumbsup:

The 4 ohm tap is no longer used for speaker output, but it can still be used for NFB.

Does the noise appear on both the low amp and high amp outputs, or low amp only?

You need only be concerned about tube type (6L6 and 12AX7). Any brand will work.

Welcome to the place!

Here's the schematic:
http://music-electronics-forum.com/attachments/31888d1418610356-1990.pdf

This could be many things. Do the filaments stay lit when the amp fades?...

Your amp uses two 6L6's and four 12AX7's. Generally, you only need to bias when changing output tubes, but it wouldn't hurt to check it even if you leave the existing tubes to verify they are working...

The diode would always be forward biased. Unless......, for some very strange reason, your cathode voltage went negative. There just wouldn't be enough bias for it to do anything unless the resistor...