Dx Blame MKIII-Hx - Builder's thread

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#802
We can't see what you have not photographed.
I and I suspect we, need an overall view.

Two red insulated cables/cords for both +ve and -ve supply.
Two blk insulated cables/cords connected to PCB Power Ground and going off pic, in different directions.
 
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#803
Rudy, the small black "isolation bushes" (Vigier called them this way) have a tendency to "break", when you fix them. I use Polyamid screws for the TO-220 and TO-126 transistors.

Please measure the resistance between the small transistors' legs and the heatsink.

Rudi
 
#805
smartx21 said:
The collectors of those 3 MJE seem to be hardly connected to the heatsink! Or is there a small isolator (dark ring)?
Click to expand...

No there is a mica isolator.
 

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#807
AndrewT said:
We can't see what you have not photographed.
I and I suspect we, need an overall view.

Two red insulated cables/cords for both +ve and -ve supply.
They are going to the 47000uF elco's
The min -60v is a black shrink hose over it so that I can see that is the min -60v


Two blk insulated cables/cords connected to PCB Power Ground and going off pic, in different directions.
Click to expand...

1 black kabel is going to the speaker terminal and the other one is going to the GND copper plate between the elco's.


Regards,
Rudy
 
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#808
No Rudy, a resistor (10 Ohm) or wire is necessary at this location (has to do with lifting up the AMP's GND-plane in correspondence
with SIGNAL GND).

I remember that there was a discussion in the very 1st posts what to use.
I did not follow this discussion to the end, but this resistor may not be left open!

Try a 10 Ohm resistor and measure again!

Rudi
 
#810
The Main Audio Ground is the reference point for a whole series of other circuits.


Signal Return
Speaker Return
PSU Zero Volts
Chassis
PCB Power Ground
Disconnecting Network, if fitted

You stated earlier that you had located your Main Audio Ground on the Speaker Return Terminal.
That means you must bring all the other reference connections to that same Terminal.

But, which Speaker Return Terminal do you use? Left or Right?
 
#815
U = R * I

1 mV = 0.47 Ohm x 2.1 mA

The value of 2.1 mA is much too small.

Keep measuring the voltage drop over an emitter resistor and very slowly decrease the trim-potentiometer's value.

Does the voltage that drops over the emitter resistor increase?

Rudi
 
#820
I power up directly from the mains, and I have the fuse in there.

when you remove the 10r bias measurement resistor, the bias will change. Upwards!!!!
Click to expand...

Andrew you mean the 100R resistor over the fuse, when I remove that resistor I cannot measure the 1mv bias anymore?
If the fuse is in there, then the 100R resistor works anymore, or should I solder out the 100R resistor?
 
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