[colliedoggy]

I have just been checking the power supply in the Mk viii SE against the schematics posted by coinmaster for the mk vi+. For the main section of power supply, there are a few differences with the values shown:
 
'R12' is two 120Ω 5W resistors in parallel (and likewise on the other side).
 
Instead of one 5k1Ω there are two 5k1Ω in parallel. (On the board is printed '3k9 2w'!) 
 
Instead of one 8k2Ω there are two 8k2Ω in parallel. On the board is printed '5k6 2w'!)

 

[colliedoggy]

The stock power stage resistors in my mk viii se are not 150 Ohms. They are actually 180 Ohms.
 
How will this change the operation of the circuit from the 150 Ohms it seems other people have?

 

[Maxx134]

All resistors are an approximate.
The zener diodes will make sure the voltages are correct.
The anode resistors being 180 ohm is not a big deal either.

My phone died so I was away for a few days.

As for the problematic output tube stage of member baronbeehive,
Do what sonic says (disconnect),

Remember very importance to realize that the amp DOES NOT have a mirror image of both sides,
So comparing sides you should realize that the pins of the good side are exact copy to other side, NOT a mirror image where things are reversed,

So yes there should be continuity on the heater pins,
And another separate continuity of two pins from cathode of one triode to plate of other, but neither of those should have continuity to chassis ground.
I suspect an error in solder or connection.

Focus on area of the burnt resistor.
A short on your cathode area would have caused it to slowly burn.
Look at where you connected everything on your cathode area.

The reason to disconnect the large cap (decoupling) is to verify it not a error in connection, and also disconnect one end of the gold rifa cap to make sure it not a shorted bypass cap.
Also check the normal bypass caps for proper connection, and also disconnect one end to test if shorted.

 

[Maxx134]

When testing caps they will briefly show some continuity as they charge up, but then go up into infinity ohm.

You can leave one end installed, total removal unnecessary

 

[baronbeehive]

All resistors are an approximate.
The zener diodes will make sure the voltages are correct.
The anode resistors being 180 ohm is not a big deal either.

My phone died so I was away for a few days.

As for the problematic output tube stage of member baronbeehive,
Do what sonic says (disconnect),

Remember very importance to realize that the amp DOES NOT have a mirror image of both sides,
So comparing sides you should realize that the pins of the good side are exact copy to other side, NOT a mirror image where things are reversed,

So yes there should be continuity on the heater pins,
And another separate continuity of two pins from cathode of one triode to plate of other, but neither of those should have continuity to chassis ground.
I suspect an error in solder or connection.

Focus on area of the burnt resistor.
A short on your cathode area would have caused it to slowly burn.
Look at where you connected everything on your cathode area.

The reason to disconnect the large cap (decoupling) is to verify it not a error in connection, and also disconnect one end of the gold rifa cap to make sure it not a shorted bypass cap.
Also check the normal bypass caps for proper connection, and also disconnect one end to test if shorted.

Yes, I intend to do what Sonic says, but it's finding the time atm.
 
I hope to have another look in the next couple of days. I've satisfied myself that it's nothing obvious, I've gone over and over the connections and pretty sure they're good but I have some suspicions of the solder around the cathode bypass like Maxx says. So I intend to have a very close look at that area, there are some solder spots which could cause tracking around the board and a dubious area of possible shorting like Sonic said. I will look at that and clean up the area very thoroughly before trying again. I noticed this with having moved some of the parts out of the way so it's easier to see around that area.
 
One thing, I'm quite surprised at how good the reverse of the board looked, and the engineer remedied the problems with the pads which was good. So I'm able to dismiss some possible causes, like the wire, for example.

 

[Maxx134]

...
One thing, I'm quite surprised at how good the reverse of the board looked, and the engineer remedied the problems with the pads which was good. So I'm able to dismiss some possible causes, like the wire, for example.

I gotta admire your interest and persistence in checking and learning,
instead of just bringing it to your engineer..

 

[baronbeehive]

I gotta admire your interest and persistence in checking and learning,
instead of just bringing it to your engineer..

 
When I've got you guys behind me, it's easy! I hadn't got a clue at first but I know there had to be a logical explanation for the problem, it's just a case of finding it. This is no more than others on this thread, it's good learning new things. I surprised myself at how good the work on the reverse of the board was but I had feeling that there was nothing wrong there, I followed the advice of Redge when he said check everything, and then check again.........and again!

 

[coinmaster]

Wait you still haven't fixed it yet? Have you tried switching the opamps like I suggested or are we beyond that issue now?

 

[baronbeehive]

  Wait you still haven't fixed it yet? Have you tried switching the opamps like I suggested or are we beyond that issue now?

 
No, I haven't forgotten that. I'm leaving that for the moment until I've fixed the short because there is an obvious issue there. Assuming I can fix it then if there is still a problem then that's next on the list.

 

[Maxx134]

I have an extra opamp if you wanna try regardless...
Hey why don't you just pull the opamp out while unit off to make sure it not a shorted opamp over there?

 

[coinmaster]

Can you explain to me in simple terms what is shorted? I don't want to decrpyt the previous messages Any issue with this amp should be easily troubleshootable unless it's high density like Maxx's in which case it would probably be annoying.

 

[baronbeehive]

  Can you explain to me in simple terms what is shorted? I don't want to decrpyt the previous messages Any issue with this amp should be easily troubleshootable unless it's high density like Maxx's in which case it would probably be annoying.

 
That's what you get for trying to be clear and simple lol! This is not like Maxx's but it is annoying!
 
Initially I noted that there was continuity between XLR output pins 1 and 2 right hand circuit, indicating possible bad connection/shorting of wires - BAD!
 
After disconnecting the wires I found that XLR output pins 1 and 2 no longer had continuity - GOOD!
 
When I got the board out I found the wires and connections OK - GOOD!
 
So following this up to look for the problem somewhere else in the faulty circuit I found that there was continuity between tube pins 5 and 6 and they were also grounded - BAD!
 
That's what led me to think there may be a short between tube pins 5 and 6 or if not there then somewhere in the faulty circuit
 
Crucially I tested from the -ive output connection on the board and there was continuity from there to the end of the -ive output wire - GOOD!
 
However there was also continuity from the -ive output connection on the board to ground, clearly indicating a short!
 
I know of no simpler way to say that......... wait.......... there's a boo boo in the works and sparks are flying and I don't like it one bit...................

.

 

[colliedoggy]

So is the continuity between pins 5 and 6 on only one of the 6N30P sockets in the right hand circuit, or both of them? 
 
If only one, is it the +ve or -ve socket?
 
Presumably, this short is with no valves in the sockets, is it?

 

[Maxx134]

Just look at the board trace in the center of the socket it clearly shows two pins connected I don't have time to pull up pics but it is from first triode of WCF circuit to second triode.
As long as they don't have continuity to chassis ground you should be good .

 

[colliedoggy]

Those are pins 3 and 6 that should be connected. Check.