And the spring reverb pan assembly is not a complete reverb system, you can;t just stick it in an amp.  it requires a bunch of suppport circuitry.

We will never know.   Parts fail.  There is often no correlation with some event.  The 2050 is far more likely to fail first over the diode.  A shorted rectifier is likely to just blow a fuse, and not partidularly likely to blow the 2050.  SO 2050 first diode second is more likely, but who knows.  Either way we have to replace those parts, and then the amop will be fine.

The loud hum was probably just DC on your speaker.

Fix it and find out.  Diodes fail, all by themselves.  DIodes also fail when somethiing else draws too much current through them.  We won't know until we get there.

How many rectifier diodes in that circuit?  Two?  Four?  They cost a nickel, replace them all.  Any remaining "good" ones were stressed by the shorted one/s.

Check your outputs for shorts.  If they show shorted, then get to work on that section too.  If they SEEM OK, they probably are.

A shorted filter cap could damage a diode, but that doesn;t really happen all that often.

You usually won;t find some reason some part fails.

Assuming transformer current can keep up.

Using a guitar cord for speakers can't hurt the speakers, might hurt the amp, but mainly is likely to work poorly for speakers.

Yes.  Just to be sure, did you try more than one speaker cord?  And is it a real speaker cord, and not just a guitar cord?  Never use a guitar cord to connect speakers.

But let's assume the cords are OK.  And you tried the amp through other speakers and it is OK.  Your cab has a problem.  Probably not because of what or how you played. 

It could be something as simple as a wire came loose.

It could be one of the speakers failed.

You have four speakers in the cab, how are they wired?  Series?  Parallel?  Series/parallel?  Since they are 8 ohms apiece, then each of those examples would result in 32 ohm, 2 ohm, and 8 ohm totals.

Clue:  you want them wires series/parallel.


Connect just one sp-eaker at a time to the amp, check each one by itwself that way.  You may find one is bad and the others OK.

A million reasons.

First, connect the amp to some other speaker.  Does it sound the same through that?  That tells us if it is the speaker or not.

If the amp is truly at fault, then check the powr supplies.  I don't know what voltages it has inside, but there will be both positive and negative.  The powr amp will work on something like 40-50vDC.  Are both of them about the same voltage?  Flip your meter from DC volts over to AC volts and measure the same two supplies.  You are now measuring the AC ripple on these DC voltages.  it should be very low, like a volt or less.

The preamp will probably run on +15 and -15 volts.  Find those, are they both about the same voltage and close to 15?  Also measure them for AC and we should see zero AC volts.

SInce I don't know the amp, old as it is it could be transistor instead of ICs, so in that case there may be only one preamp supply.  Still should be free of ripple.

And go through the stages l;ooking for unwanted DC offsets at each stage.

Fisrt, keep searching the internet, and indeed this forum has its own search.  I think the 2000 may have been posted here.  There are a bunch of Behr schematics floating online.  Usually page 4 or 5 of google before you get to them. Seems to me there is a site in Hungary or somewhere in that part of Europe with a bunch of them. Also, though it looks like an X, I think you may have a PMH2000.  SO search both PMX and PMH.

However, Most Behringer schematics do not include the mains wiring anyway, including this one.  But this is a very conventional amp.  The mains come in, got your standard things like power switch, inrush thingie, fuse, and power transformer primary.  Oh I think the primary side also runs through one of those thermal breakers on the side of the power amp cover.  The wiring is accessible, so see if your mains is getting to the primary wires of the transformer.  If not, simple tracing will find where the mains is being interrupted.

How old is it?  Is it a tube amp or solid state?  If tube, is there a small reverb transformer or not?

Thanks.  That is one of those things I just cannot remember.  You can tell me, but in a week, if you ask, I will have forgotten.   SOme things just won;t stick in my head.

yes yes yes use a tooth washer behind the panel.  You can snip off or bend flat the tab.   Or bite the bullet and drill the one extra hole per.  To me, when I see the locator hole next to the pot, I think of it as attention to detail.

And Loctite on the threads too.  Get the right Loctite, they make some that is "permanent" and some meant to be removable.  You want the remiovable kind.

Don't aim your laser focus at lack of filtration as your hum source.  The hum turns down with the volume control.  If there was bumpy B+, you'd still get some hum, I;d think.

First, is the hum 60Hz or 120Hz?   120Hz is power supply ripple, 60Hz is not.

Try swapping tubes around, any help?

Even if it is power supply ripple, it may be ripple currents through shared ground, rather than lack of filtration.

The volume control controls the hum level, so at the grid of the stage previous to the control, tack a ground wire from grid to the ground end of the cathode resistor.  Soes that silence the hum?  (It will also silence the signal)

This could be one instance of heater related hum.  How is your heater line grounded?  Center tap?  virtual center tap?   Have you tried elevating the heaters?

70-503-41 is the complete part number.  MOST Crate pots have the resistance as th center grouping, read like colors, so 50k here.   But you cannopt rely on that, other than that I looked it up

If your resistor stripe is OK, you can reassemble a new shaft into it from any other pot in that series.

Perhaps at some time in the future if you find yourself divorced, You may come to understand that similar emotions exist in business.

I thought I had some Gorilla schematics, but not in my files.  I'll see what I can find in my papar files.  I may look in my old computer, but that is way less likely.

JM, I don't recall where you posted it, but I liked the photo of a sheet of bare boards, ready to stuff with parts.   If I recall you had something like 20 circuit boards on one large board, which I assumed you could snap apart to make 20 amps.