QUAD 34 help needed

lmunasi · 8th March 2008, 04:29 PM

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 · 8th March 2008, 05:31 PM

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 · 8th March 2008, 06:07 PM

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 · 8th March 2008, 08:18 PM

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

Andy

lmunasi · 8th March 2008, 09:32 PM

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

8th March 2008, 04:29 PM	#1
lmunasi diyAudio Member Join Date: Mar 2008	QUAD 34 help needed 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,

8th March 2008, 06:07 PM	#3
Jan Dupont diyAudio Member Join Date: Apr 2003 Location: Copenhagen, Denmark	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.... __________________ Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com

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8th March 2008, 05:31 PM	#2
poynton Magneto the Gravity Man diyAudio Member Join Date: Mar 2005 Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)	Email Quad in the UK. If you explain the problem, they will help even if only to email / fax / post the circuit. Andy

8th March 2008, 08:18 PM	#4
poynton Magneto the Gravity Man diyAudio Member Join Date: Mar 2005 Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)	The regulator may be dead IC21 or the opamp IC23 (provides the ground 0v ) You will have to probe with a meter. Andy

8th March 2008, 09:32 PM	#5
lmunasi diyAudio Member Join Date: Mar 2008	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

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