Eden WT-800 low/distorted output

[Danglin' Fury]

So, I have this on the bench. Got the schemmie, been goin through it. If I plug directly into the effects return both post eq and pre eq, it sounds equally as distorted/ fading in and out as when I plug into the actual amp input. Havent had a chance to run a line from the send to a different amp but I believe it to be in the power section and something that affects the left and right power modules in this thing. Anybody have any ideas where it could be? The power supply? On the schemmie, it says off R7 Im supposed to have 125 V. Im reading 150V. Thanks for looking. any help would be immensely appreciated.

[g1]

Can you post the schematic?

[Jazz P Bass]

Eden WT800 Schematic

Always check the power supply.
Especially if the problem is in both modules.
Anyway, the 125V line is for the tube plates.
If it is high the tube circuit may be at fault.
Check for plate & cathode voltage.

[Danglin' Fury]

I will indeed check the power supply. By plugging into the effects return isnt that bypassing the vacuum tube?

[Jazz P Bass]

Yes it bypasses the tube.
I am not saying that is the power amp problem.
You had asked why the 125V line is high.
The voltage that you read is higher than the schematic indicates.
So check the plate & cathode.
2 seconds & you are done.

[Danglin' Fury]

Measured 87 VDC on the plates and 500mV on the cathodes. But as I was taking the measurements, a hissing came from the 10,000 uF caps in the power supply. They were very hot to the touch. I took them off the board because I couldnt get a reading of their values. After they cooled down, They read from 9,210 uF-9,350 uF. Could the large rectifier chip for the high voltage be bad? Thanks.

[J M Fahey]

1) Did you or anybody replace those filter caps before?

2) the schematic shows the filter caps but not the transformer or the rectifier bridge, which apparently come through a connector labelled T6/7/8 .
Did you disconnect and reconnect it?

3) What DC voltages do you measure across each 10000x80 capacitor legs?
At the legs themselves.

4) the schematic shows some mistakes, such as a floating tube cathode, a 1000x10V bypass capacitor on the -HV rail, etc, so it's not *that* trusty.

[g1]

Hot filter caps always make me wonder about the line voltage. Saw an Orange amp a couple weeks ago that had a 100 or 115V line voltage select switch. It was blowing fuses, someone had set the selector to 100V. Fortunately, no serious damage. I've seen plenty of amps with 120/240 switches but never 100/115.
Like JM said, check what kind of DC is at the filter caps. And what their DC rating is.

[Jazz P Bass]

It could just be a bad cap.
End of life.
OR, the rectifier truly is bad & it's passing Vac.

[g1]

Yep, but the combination of the high HT for the tube plus the filter caps venting & overheating got the alarm bells going off .

[J M Fahey]

First thing I checked was poster's location suspecting a 220/240 V Country and 110/120V amp.

There's also another case which I see it all the time in Brazil.
They have the largest Japanese population outside Japan, and it's a local tradition to send kids just after they finish High School to Japan, to work for 1 year at some Factory, both to "keep Traditions/Culture alive", to learn to work in a well organized environment, etc.
Kids usually buy guitars and amps ... 100VAC of course , and trouble starts as soon as they get back to Brazil.
Doubly so because they are turning towards 127V home power.

[Danglin' Fury]

The caps at the resistors read 85 V DC for the +, -85VDC on the neg side. Didnt have much time as I didnt want the caps venting in my face. Caps are off the board now as I couldnt get an accurate reading. out.of circuit, and cooled down they read pretty close to 10,000 uF. The schemmie says they are 80 volt caps but these are 100VDC. I havent changed the caps dont know about anybody else. i currently have the power supply board out and the 10,000 uF caps off the board as well. Anything coming to anybody's mind? the rectifier?

[J M Fahey]

Sorry for being dense, but we are chasing ghosts here so what " looks" normal sometimes is not.
Can you please measure voltage across the cap terminals themselves?
Even if voltage at rails is normal, they might have been wired (by mistake of course) rail-to-rail which is the same as feeding 220V to a 110V amp.
Also check your actual line voltage, and what VAC you measure across transformer secondary wires and from each secondary wire to ground..

Yes, these are redundant measurements, that's the idea.

[Danglin' Fury]

Once again, power supply board out and caps desoldered from board. Just put 85 VDC on the caps individually and no problems. They bled off but not unusually fast. Gonna put the caps back on the board and the power supply board back into the amp and see what happens. Gonna try to measure the rectifier first. Thanks for your help fellas. I REALLY appreciate this.

[Jazz P Bass]

Oh, for sure check out that rectifier circuit.
Make sure that the ripple (unfiltered) is within a decent range.
Seeing that only one cap was hissing, you may find that one side of the rectifier is passing Vac. (more so than the other side)
Vac on a cap is not good for it's health & well being.
If it is a rectifier problem (passing Vac) I would recommend replacing the caps after repairing the bridge circuit.