Randall rg75d humm

[cmanningjr]

Do you mean that this black wire just solders to the underside of the board? What does it connect to on the front panel board?

There is no easy fix here, you will have to methodically retrace your steps and check everything that you did against the schematic drawing.

You know that the resistor that is burning is in the high voltage power supply for the tube, so start there. Identify the connector that carries the high voltage from the power supply board to the tube. Pull the connector at one end and measure the resistance to ground at both ends of the wire. Is either side a low or zero reading?

Hopefully there wasn't a lot of damage done when whatever went wrong, went wrong.

Yes it is solderd to the front board to the pin on the cap closed to the edge of the board. I should have paid closer attention to what I was doing but didn't...Now here's where I am..

I don't expect it to be an easy fix...Again I really appreciate all the advice and tips..

[cmanningjr]

Ok,

I unplugged QC14 and it does not over heat. The black wire that is soldered to the bottom of the board is on C11 (Cap I replaced) on the side with the stripe. It goed to the cap on the front board and is soldered to the pin on the non striped side....As I type this I am trying to have a flashback that that black wire goes on the other side of the cap...

[J M Fahey]

Agree and add:"remembering what it was like before" is no longer the point.
That may help if you, say, pull just *one* or *two* wires to have access to something, nothing more complex than that.
Once the dismantling advances, even a hand drawing or a picture don't tell the full story.
Fully agree with 52 bill and expand it to this: consider this an amp which you never saw before, and know "somebody" messed with it.
Now, suspect everything and compare it part by part, connection by connection to the schematic.
Make 3 or 4 photocopies (just in case), take one, check a single item (where it is, what it connects to) both "live" and on paper; when checked mark it with fluo highlighter and only then pass to the next one.
Same with connections (use other colour).
Only when the paper is fully painted you'll know it's back to original.
STILL WITH BAD PARTS , but at least measurements can be trusted.
It may also help to leave it aside for, say, a week and forget it, then start again fresh.
Good luck.

[52 Bill]

I unplugged QC14 and it does not over heat.

Then the short is in the circuit connected with that wire. What color wire did you pull? Where does it go to?

The black wire that is soldered to the bottom of the board is on C11 (Cap I replaced) on the side with the stripe. It goed to the cap on the front board and is soldered to the pin on the non striped side....

I don't have the schematic open right now, is C11 on the positive side or the negative side of the power supply? When you did the earlier work, did you unsolder the black wire from the front PC board or only the side on the power supply board?

While the black wire may be in the wrong place, I don't think that it has anything to do with the burning resistor in the high voltage power supply. I may be wrong, but let's not jump to the conclusion that it is the cause of the problem.

[cmanningjr]

Well, I have to say...I can't fix it...This is beyond my capabilities....

[52 Bill]

Well, I have to say...I can't fix it...This is beyond my capabilities....

Sorry to hear that, but you are the best judge of your abilities. If you take it into a shop take a copy of the schematic in with you and give them a brief explanation of what you did to the amp. They may be able to sort it out for you.

I think that you connected the wrong wire to the high voltage power supply, which caused the resistor to burn. Hopefully whatever was connected to the high voltage supply was not damaged.

[diydidi]

Please post schematic

[52 Bill]

Please post schematic

Hope this works

[g1]

52Bill: can you zip those? Only the supply pdf is working.

[Jazz P Bass]

Randall RG75 Schematics

This is everything that I have for the RG75.

[52 Bill]

Let's see if this works

[diydidi]

Thanx guys!!!!!!!!!!!