Quad 33 and FM3

[alanworland]

I know what you mean with the thumps and bangs! I only have the 303 but it can be quite frightening!
Give your switchboard a good grilling for intermittency.


Alan

[Craig]

Edge connectors. My 33 went into pops and bangs when tapping the case too. Do what it says in the service manual, and gently push the connector fingers in a bit with a suitable tool. Apparently the vast majority of 33's that were returned to Quad for fixing had that problem. They later changed the edge connectors for gold plated ones to overcome the problem. Except they still relax over time.

The other thing that went on mine (which was also a pops and bangs when tapping the case event) was the on/off switch on the back of the volume control - it had burned clean through one contact. Cured that by buying a NOS single gang control on eBay that had the same AB brand switch. Removed it and put it on the old control. Sorted.

[ppppenguin]

Mine has gold plated fingers but I'll squeeze up the contacts anyway. Must remember the tape and disc adaptor cards too.

My 33 was fine until I took it out to replace electrolytics in the PSU and main board. Perhaps I should have left it well alone

Thanks for reminder about the on/off switch. I'll bridge it out to check. I have a complete spare volume control assembly, bought from Quad some years ago against something like this happening. I wonder where I've hidden it.

[ppppenguin]

A real "Doh!" fault. Once I had it on the bench under a good light and easily accessible it became obvious very quickly that the solder joint on the 0V wire from the PSU board to the rest of the amp had failed due to repeated flexing.

[Craig]

Well done! It is always a relief to find the cause, particularly when intermittent.

[alanworland]

Great! Does it now work? and is it better?

Alan

[ppppenguin]

All works fine. Haven't done enough listening to be able to say if it's better but first impression are good.