Calibra DIGI 1600

[chrisg4]

Ok, figured out the issue, my psu wasn't supplying enough voltage.
changed to a different 12v supply and pin 9 & 10: 3V

 

[Perry Babin]

OK. with the rectifiers, do you now have rail voltage?

 

[chrisg4]

On which pins should i measure the rails?

 

[Perry Babin]

Measure it on the output of the power supply filter inductors.

 

[chrisg4]

Hi, yes rails are present: 167v on both inductors

 

[chrisg4]

This wave is present on all gates of outputs

 

[Perry Babin]

On AC coupling, drive signal waveforms are useless.

 

[chrisg4]

oh my mistake.

the high side square wave rides @ 48v
low side rides @ 48V

 

[Perry Babin]

They can't both be at 48v.

The low side should have an amplitude of 10v originating on the negative rail and driving from there towards ground.

The positive drive should do the same from the positive rail.

 

[chrisg4]

the low side fets = G: -183v ; D: -37v ; S: -193v
high side fets = G: 155v ; D: 0v ; S: 165v

 

[Perry Babin]

Was the black probe on the secondary ground?

 

[chrisg4]

no, i used main ground terminal

 

[chrisg4]

By secondary ground, do u mean the ground from the transformer?

 

[Perry Babin]

The secondary ground is generally the center-tap on the transformer's secondary windings. Often the negative speaker terminal and sometimes the RCA shield.

 

[chrisg4]

ok thanks

i'm using my multimeter to measure.

black probe on secondary ground
high side fets = G: 71v ; D: 0v ; S: 82v

swapped the probes for the low side
low side fets = G: -240v ; D: -82v ; S: -250v

the other set of outputs:

low side fets = G: -71v ; D: 0v ; S: -82v


high side fets = G: 240v ; D: 82v ; S: 250v

 

[Perry Babin]

I have no clue how you're getting over 200v.

The source voltage indicates that you have a rail voltage of ±82v.

 

[chrisg4]

Neither do I.

What would be the correct drivers for this output circuit?

the drivers that look original and untouched are

2SC3503
2SA1704
2SC2803
2SC2803
2SA1704
2SA1381


somebody installed BD139 in place of three of the above....

 

[Perry Babin]

Post a good quality photo (in focus, no flare from the flash...) showing the ICs in the rectangle I need to be able to read the numbers on the ICs.

 

[chrisg4]

 

[Perry Babin]

Do you have a square wave of about 80kHz on pin 5 of OU1?