Cambridge Azur 640A Version 1 Amplifier Repair (With Audio Tutorial)

Fault 1
Standby switch intermittent operation.
Common issue due to the PCB mounted momentary push button contacts becoming worn and oxidised over time.
Replacement push button fitted, fixing the issue.
Fault 2
Intermittent loss of Audio on the left channel RCA, CD input.
Replacement Phono socket assembly fitted, and broken solder pads also repaired with link wire fixing the issue.
Due to the age of the Amplifier the speaker protection and power start up relay were replaced. ME-110122Z4
User controls and switches cleaned with De-Oxit to ensure noise free operation.
Bias for each channel reset back to 13 millivolts.
Amplifier fully tested working correctly.

[@matthewbeeson5612]

Thanks for this very clear and helpful video. I have the switch issue with both my 640A and 640C and have new switches ready to fit. Could you share the dimensions of the neoprene washers? I’d like to get some ready to do the job in one go. Thanks 😊

[@AudioAmplifierServicing]

Hi these are the types of washers you can use check sizes www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2334524.m570.l2632&_nkw=foam+washers&_sacat=2562&_odkw=amplifier+broken&_sop=10

[@matthewbeeson5612]

@@AudioAmplifierServicing That’s great, thanks

[@matthewbeeson5612]

I ended up buying a set of nitrile o-rings and using 2 per button. The power button is a larger diameter than the other buttons. For the Power I used 10 x 1.9mm + 14 x 2.4mm and the others I used 10 x 1.9mm + 12 x 2.4mm.

[@AudioAmplifierServicing]

@@matthewbeeson5612 Appreciate you sharing your experience on the channel.