QUAD 34 help needed

[lmunasi]

New user to diyaudio and would appreciate some help. I picked up a QUAD 34 control amp that needs work. Here is the story:

SN on unit is 8966. The unit does not want to power up. I have checked the fuse and the transformer. The green LED (D33) lights up but nothing else. The unit appears to be in original condition without any mods. I realize that these have had problems with some of the electrolytic capacitors. I intend to change the OP amps once I figure out what the problem is. I do not have a service manual for this unit.

Any help in troubleshooting would be greatly appreciated.

Thanks,
😕

 

[poynton]

Email Quad in the UK.

If you explain the problem, they will help even if only to email / fax / post the circuit.

Andy

 

[Jan Dupont]

I have had a 34 for many years. Bought it as original, but did a heavy mod on it.

It sounds very strange that the D33 will light up, and the amp still won't start up 😕

Here you have the schematic

Rob Flain from Quad has been a great help to me....

 

[poynton]

The regulator may be dead IC21 or the opamp IC23 (provides the ground 0v )
You will have to probe with a meter.

Andy

 

[lmunasi]

Thanks for the reply and the schematic Andy and Jan. I will email Quad for help. Shall keep you posted of what I learn.

Lochi