XTR 4000.1D

[Hexhclass]

This amp has rail voltage but the voltage for the op-amp is missing.The circuit that produces that voltage is there a tap from the transformer that feeds it or it’s tap from the rail?

Any suggestions

 

[Perry Babin]

What's the DCV on each end of R597 and R598?

 

[Hexhclass]

0v

 

[Perry Babin]

There are likely three 2.7 ohm resistors in parallel What resistance do you read across them?

 

[Hexhclass]

Three 4.7 in parallel, read 2 ohms across

 

[Perry Babin]

Check the transistor on the small heatsink, Q584.

Copy and paste the following list and fill in the blanks.

DCV on all terminals of IC581?

Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:

 

[Hexhclass]

Which ground do I used

 

[Hexhclass]

Pin 1: 3.782
Pin 2: 0.046
Pin 3: 0.000
Pin 4: 1.572
Pin 5: 0.000
Pin 6: 0.000
Pin 7: 7.60
Pin 8: 1.726

Using negative rail for reference

 

[Perry Babin]

Sorry about not specifying the ground/reference. You got it right.

Same reference, DCV on all 3 terminals of Q581?

 

[Hexhclass]

1: 0.000
2: 283v
3: 0.000

 

[Perry Babin]

283v?

I'm working from a mix of information but I wouldn't expect anything near that.

 

[Hexhclass]

143v using main ground and 283 using negative rail

Voltage on the rectifiers 143v

 

[Perry Babin]

Are all of the power supply FETs being driven? Confirm that all of the drain waveforms look the same.

 

[Hexhclass]

Yes all are being driven.

 

[Perry Babin]

DCV on each end of R580? negative rail as reference.

 

[Hexhclass]

-0.001 on both ends

 

[Perry Babin]

Does this amp have a TIP41 transistor (or any transistor) as a regulator that produces the voltage for the 2110/2113 output driver IC? Does that IC have 15v on pin 11 (referenced to the negative rail)?

 

[Hexhclass]

Pin 11 has 0v
It’s is connected to R580 that is connected to pin 2 of a SMD BE transistor.I pull that transistor and it tested ok.

 

[Perry Babin]

Which transistor are you referring to?

 

[Hexhclass]

Q581