Cambridge Azur 640A V1 Buzz

leviathon · 24th May 2010, 10:43 PM

Still working on other stuff on this forum. Thought the following would be a no brainer. Sigh...

Looking to fix my son's integrated. It buzz's upon start-up then (mostly) goes away after about 30 minutes.

Buzz is there without any signal, only speakers hooked up.

Observed that if you turn the volume up, the buzz disappears around the 9 to 11 o'clock area, then starts again.

I have tried cleaning the volume control pot, and all other pots for good measure to no effect. (MG Chemicals zero residue spray)

I still thinking the volume control, but weird that after warm up the buzz fades.

Any help would be appreciated.

Ed

Ian Finch · 13th June 2010, 02:15 AM

OK Ed, we are here now. Others may follow now with some better advice once inside the amp. I admit I have never checked inside a Cambridge of this Azur species before but some general principles will apply to all SS amps. I believe this is a conventional class AB type and not the XD type of 740 and 840 models. Anyways, I guess we'll hear from you after the father's day activities.

jaycee · 13th June 2010, 03:00 AM

id look for a bad capacitor in the signal path

leviathon · 13th June 2010, 05:47 PM

Gaaaa. First thing I realized after I slept in... Father's Day is next weekend, June 20th! So I got that straightened out. Will work with suggestions given. Thanks all!

Ed

Mooly · 13th June 2010, 06:55 PM

Both channels affected or just one ?

jaycee · 13th June 2010, 08:21 PM

Listen to the signal at the pre-out sockets. Does that have the buzz too?

jaycee · 13th June 2010, 08:35 PM

Here's the service manual

leviathon · 18th June 2010, 01:24 AM

Thanks Jaycee,

Lot of things to test that I had not even thought of to help narrow the problem down.

I will be able to do some poking around this weekend.

Ed

leviathon · 20th June 2010, 10:09 PM

Buzzing at pre-outs when hooked up to a separate amp and speakers (both L &R), no source! Great tip. That narrows things down. Will start looking at caps, wires and such in signal paths.

Th3 uN1Qu3 · 20th June 2010, 11:18 PM

Since it goes away after a while it's definitely a bad capacitor.

24th May 2010, 10:43 PM	#1
leviathon diyAudio Member Join Date: Oct 2009 Location: Winnipeg, Manitoba	Cambridge Azur 640A V1 Buzz Still working on other stuff on this forum. Thought the following would be a no brainer. Sigh... Looking to fix my son's integrated. It buzz's upon start-up then (mostly) goes away after about 30 minutes. Buzz is there without any signal, only speakers hooked up. Observed that if you turn the volume up, the buzz disappears around the 9 to 11 o'clock area, then starts again. I have tried cleaning the volume control pot, and all other pots for good measure to no effect. (MG Chemicals zero residue spray) I still thinking the volume control, but weird that after warm up the buzz fades. Any help would be appreciated. Ed

13th June 2010, 02:15 AM	#2
Ian Finch diyAudio Member Join Date: Apr 2010 Location: Coffs Harbour, on the east coast	OK Ed, we are here now. Others may follow now with some better advice once inside the amp. I admit I have never checked inside a Cambridge of this Azur species before but some general principles will apply to all SS amps. I believe this is a conventional class AB type and not the XD type of 740 and 840 models. Anyways, I guess we'll hear from you after the father's day activities. __________________ regards

13th June 2010, 06:55 PM	#5
Mooly diyAudio Member Join Date: Sep 2007	Both channels affected or just one ? __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

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13th June 2010, 03:00 AM	#3
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	id look for a bad capacitor in the signal path

13th June 2010, 05:47 PM	#4
leviathon diyAudio Member Join Date: Oct 2009 Location: Winnipeg, Manitoba	Gaaaa. First thing I realized after I slept in... Father's Day is next weekend, June 20th! So I got that straightened out. Will work with suggestions given. Thanks all! Ed

13th June 2010, 08:21 PM	#6
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	Listen to the signal at the pre-out sockets. Does that have the buzz too?

13th June 2010, 08:35 PM	#7
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	Here's the service manual

18th June 2010, 01:24 AM	#8
leviathon diyAudio Member Join Date: Oct 2009 Location: Winnipeg, Manitoba	Thanks Jaycee, Lot of things to test that I had not even thought of to help narrow the problem down. I will be able to do some poking around this weekend. Ed

20th June 2010, 10:09 PM	#9
leviathon diyAudio Member Join Date: Oct 2009 Location: Winnipeg, Manitoba	Buzzing at pre-outs when hooked up to a separate amp and speakers (both L &R), no source! Great tip. That narrows things down. Will start looking at caps, wires and such in signal paths.

20th June 2010, 11:18 PM	#10
Th3 uN1Qu3 diyAudio Member Join Date: Feb 2010 Location: Bucharest	Since it goes away after a while it's definitely a bad capacitor.

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