Calibra DIGI 1600

[chrisg4]

Hi all,

received this amp in this condition, it is in protection.

can someone assist with a schematic please?

PSU has IRFP2907 & IRFP064N

Outputs are IRF640 & IRF9640

 

[chrisg4]

 

[Perry Babin]

Have you done any troubleshooting?

 

[chrisg4]

Hi Perry,

Yes. There are no shorted mosfets. I pulled the rectifiers and psu seems to work. I get + 63 and - 63 rails. I stopped there.

 

[Perry Babin]

Is the fixative around those green resistors conductive?

 

[chrisg4]

Doesn't appear to be conductive

 

[chrisg4]

Hi,

I removed the outputs and installed the rectifiers, amp relay engages but i don't have any rail voltage. Could the rectifiers be defective?

 

[Perry Babin]

What do you read if you measure the DC voltage across the output terminals of each of the two PS filter inductors?

 

[chrisg4]

12v across both

 

[Perry Babin]

How did you get ±63v with the rectifiers out of the amp?

 

[chrisg4]

I was sure I saw 63v on the dso scope when i probed the centre leg traces of the rectifiers... I could have been wrong

 

[Perry Babin]

The rectifiers needed to be in the circuit when you measured the voltage on the inductors. Were they?

The voltage was likely from charged rail caps.

What's the resistance between the negative speaker terminal and the primary ground terminal?

What's the resistance between the RCA shields and the primary ground terminal?

 

[chrisg4]

Yeah I reinstalled them and measured.

Both resistance read 991ohms

 

[chrisg4]

I've tested the rectifiers with a multimeter, they seem fine as well.

 

[Perry Babin]

It appears that there is some conflicting information. Measure the voltages in the next few posts without making any changes. Have all components in the circuit.

What is the DC voltage on terminals 9 and 10 of the PS driver IC?

 

[chrisg4]

I've ordered new parts, will install and take readings. Must i install the outputs as well?

 

[Perry Babin]

No. Did the outputs fail?

 

[chrisg4]

none of them were shorted...

 

[chrisg4]

With rectifiers installed - TL494 pin 9 & 10: 0.3v
without rectifiers - TL494 pin 9 & 10: 3v (square waves on gates and drains)

 

[Perry Babin]

Are you saying that there is nothing but 0.3v of DC on 9 and 10? And absolutely no drive signal?