Wednesday, September 26, 2007

Quad 44 Erratic Input Switching

Thanks to Henk Vocks (NL) we can publish Quads paper on input-switching problems in some 44 preamplifiers.

The date of the Quad paper is 23/05/90 and the ref. is M12436-5.


A small number of 44 control units appear to be subject to pulses, triggering the electronic switching causing the unit to change from the input selected either to another input or to no input at all. The required input can then be regained by pressing the appropriate input selector button.

The cure is to:

  1. Resolder both sides of the 10 feed through pins marked D, E, +, -, B, C, H, G, F and A on the mother board. Ideally the pins should be replaced with tinned copper wire. The pins are ringed in the attached diagrams.

  2. Connect a capacitor min 4,7 µF across the +8,5V and -7,5V rails on the back of the mother board, as shown.

You can download this paper from the download-section of our website



Anonymous Anonymous said...

Dear Sir,
I got a new QUAD 44/33 BACK IN 1987.
It worked fine for the first 3 years approx.Then "erratic switching" appeared.It would just switch to the first input i.e. Radio. I took it at least 3 times to the service centre in Barcelona where I live but the repairs were short lived. On a later
occasion I was in London and fixed a visit with Quad in Huntingdon.It was fixed within the day for about 70 pounds.Back in Spain it worked fine for about six months then erratic sitching again. I wanted to buy another amp then I solved the problem. I got a 4way audio input control unit and am using the the first input only. It has has been working fine for at least 4 years.

My name is Felix and this my address.

4:20 PM  
Anonymous Anonymous said...

What a great resource!

9:50 AM  

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