Quad 34 psu capacitor.

  • No one logged in.

06-Jun-2013 07:55 PM

felix

felix

Posts: 84


Hi,

I was doing a revision on a Quad 34 which is a later grey model and I noticed that C69 was fitted the wrong way round to what was marked on the pcb eg the negative leg of the capacitor was fitted in the positive hole,  I checked the circuit diagram and it should be the other way round. has anyone else had this?
Regards Felix.








  Reply

07-Jun-2013 08:13 PM

John Bean

John Bean

Posts: 75


Very strange Felix, the preamp work well?

Measuring just with voltmeter across the capacitor to see what the plus or the minus should be.
Replace the capacitor in any case because he certainly defective.


John.

  Reply

08-Jun-2013 12:36 AM

felix

felix

Posts: 84

Hi,

I have replaced the capacitor now the right way round but the strange thing is the amp worked ok with the capacitor reversed!

Regards Felix. 

  Reply

08-Jun-2013 02:53 AM

EJP

EJP

Posts: 1605

It's surprising. As you can see, C69 is part of the initial mute circuit. If it couldn't hold a charge I don't see why the mute should ever un-mute at all. It must have just failed completely open-circuit so there was no initial mute at all.

Dada Electronics Australia
  Reply

22-May-2019 12:16 PM

Rich M

Rich M

Posts: 6

It may have vented (or not) and partially re-formed in opposite polarity. I found similar with both channels' C7s in my 1994 606-2 when re-capping 5 years ago. They had bulged and were brown stained but still measured 22uF of their marked 47uF and the amp still worked well.
  Reply