[coinmaster]

I still don't see what you're talking about there's no -ive label nor do I see any XLR exits.

 

[baronbeehive]

  I still don't see what you're talking about there's no -ive label nor do I see any XLR exits.

 
Where it says R_OUT - with a (3) underneath indicating pin 3, that is the right hand negative point on the board circuit which goes to the right hand negative pin on the XLR output on the chassis back panel. It goes there via pin 5 which is where the output wire to the XLR's is connected. There is also a R_OUT + which is on the board just below the fuses, and a ground point also.

 

[baronbeehive]

  Today is a glorious day, I finally purchased another MK6 lol. I turned off my brain and just clicked the buy button before logic and reason returned to me 

Also the fact that I'm constantly waiting on parts made me realize that my prototypes will never be a good way to just listen, at least not anytime soon. Dear god help my bank account.

What have you been using for music listening then? At least I've got my speaker amp

.

 

[coinmaster]

The R_OUT -  is the cathode. The output to XLR should be on 5 or 6. If the cathode is reading ground then you have a problem. If the XLR out is outputting from this ground you also have a problem. Show me pictures of the backside of this area. Also make sure you are measuring from the proper ground. I usually just stick the probe in the big metal hole between the large psu caps for convenience as it is directly tied to ground.

 

[coinmaster]

What have you been using for music listening then? At least I've got my speaker amp 

.

Nothing 

 
Also I take it back again, I was going off the top of my head before, 3 and 5 should be connected not 5 and 6 so if 5 and 6 are connected then you got probs. Remove tube and test again and check backside of board.

 

[baronbeehive]

  Inside right hand (bad) circuit : cathode bypass/resistor, coupling cap, WCF, anode resistor connections.
 


Inside right hand (bad) circuit : -ive output connection.
 


Both right hand circuits : cathode bypass/resistor connections.
 


Both right hand circuits : heater wire connections.
 


Outside right hand circuit : cathode bypass/resistor, WCF, coupling cap, connections.
 


Outside right circuit : anode resistor connections.
 

 

 

  Nothing 

 
Also I take it back again, I was going off the top of my head before, 3 and 5 should be connected not 5 and 6 so if 5 and 6 are connected then you got probs. Remove tube and test again and check backside of board.

 
As before, pins 3, 5 and 6 are grounded and connected.

 

[coinmaster]

6 shouldn't be grounded. The only thing that should be connected to 6 is the cathode resistor and bypass cap.

 

[baronbeehive]

  6 shouldn't be grounded. The only thing that should be connected to 6 is the cathode resistor and bypass cap.

 
No, it shows continuity with the cathode bypass and resistor but is grounded. I've looked at the tube sockets and there doesn't seem to be any way that there could be a short between pins 5 and 6 so it must be somewhere else in the circuit. I keep on checking the wiring, connections etc. and can't see anything relevant at all.

 

[colliedoggy]

Did you change the wiring to the rear pre-amp out sockets at all?
 
Is there any possibility it could arise from that?
 
(Yes, I am in preparation for modding. I am still putting together a parts list.)

 

[colliedoggy]

Have you done anything with the volume pot?

 

[baronbeehive]

  Did you change the wiring to the rear pre-amp out sockets at all?
 
Is there any possibility it could arise from that?
 
(Yes, I am in preparation for modding. I am still putting together a parts list.)

 
Yes I've changed the wiring, and I did think initially that it was that as that was when I first spotted the grounding issue at the XLR's. But I've disconnected the wires and there's still the same issue so it must be somewhere in the circuit, not the wiring.
 
BTW good luck with the mods

.
 

  Have you done anything with the volume pot?

 
No.

 

[Maxx134]

-ive = negative...

I did not realize this abbreviation at first either.
Lol

Check out coinmaster suggestion as he has the MK6 not me

 

[Maxx134]

I would like to point out at this time for the importance and necessity and cooling the amp not because of the tubes,
but mainly and specifically because of the Transformers winding for the driver stage...

If you look at the Transformer schematic (posted in thread), you will see that the winding for the driver Stage is the weakest link..

In other designs, if you do not have enough heater current,
it just simply Taps out..

But in this design, the driver tube heaters are connected direct to the Transformer without any type of protection.

So what we have is a circuit in which a Transformer tries to deliver whatever the current demands,
no matter tube so increased heat until shorting/failure of the Transformer heater windings..

Only the driver Stage has this potential possibility when using rolling tubes not designed for the amp but a similar effect can be accomplished with letting the amp Transformers overheat.


So make sure your Transformers are not blazing hot,
or you risk a short in your driver coil windings..

I had this unfortunate incident a few months ago,
of using an adapter which shorted out my driver Stage..
I fell asleep and woke up with a non-working left side.


I didn't even know it failed because my ground fault protection Outlet was triggered and shut down AC..
I use and recommend a hospital-grade isolation transformer for all audio equipment.

Anyways, the point is you don't want to have to order a replacement Transformer,
As then you will and end up waitIMG almost a month for replacement Transformer,
Which is nice heavy item:


It's alot of wires too.
So take care of any heat issues.

Replacement need access to covers and inside bolt holding it.


Anyways I have taken a break from completing my mods to actually enjoy the amp.

Too much testing of driver stage was problem.
Anyways if you want to roll any tube, then a separate PSU for the heaters would be optimal,
Which is another uncompleted mod lol.

 

[coinmaster]

 

 it shows continuity with the cathode bypass and resistor but is grounded. I've looked at the tube sockets and there doesn't seem to be any way that there could be a short between pins 5 and 6 so it must be somewhere else in the circuit. I keep on checking the wiring, connections etc. and can't see anything relevant at all.

 

Are you saying there is continuity between 6 and ground? How are you measuring ground?

 

[Maxx134]

 it shows continuity with the cathode bypass and resistor but is grounded. I've looked at the tube sockets and there doesn't seem to be any way that there could be a short between pins 5 and 6 so it must be somewhere else in the circuit. I keep on checking the wiring, connections etc. and can't see anything relevant at all.

Are you saying there is continuity between 6 and ground? How are you measuring ground?

Good question.
He needs to be sure of what is just continuity, from what is "being grounded"..