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Old 19th October 2008, 02:36 PM   #1
APE-MAN is offline APE-MAN  United Kingdom
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Join Date: Oct 2008
Default Cambridge Audio A500 is dying.

Hi

I have a Cambridge Audio A500. I have owned this amp along with a pair of Celestion F3's since Jan 2001 and everything has worked fine until I decided to listen to Definitely Maybe this morning, then I heard a loud crack and the left channel decided to blow the living day-lights out of the LF speaker.

I have done a bit of basic testing. In a nutshell: The left output is knackered, it is just outputting a very high signal that my LF speaker was not too happy about (luckily the MF and tweeter survived). Any advice on what I might do next or how to repair!! My 12 years old HNC in electronics isn't serving me too well now.

In addition, I have dug my old multimeter out and the left channel, with no audio going into the and is outputting 40VDC, where as the right channel is 0V.

Thanks in advance to anyone who responds.
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Old 19th October 2008, 05:53 PM   #2
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Full DC at output means blown output transistor(s). Check them and their drivers plus all surrounding components as well or the IC if it is a chipamp. Replace what is broken or probably broken. Or take the amp to a repairshop, if you are not too sure about things.
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Old 19th October 2008, 11:29 PM   #3
jaycee is offline jaycee  United Kingdom
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Location: Norwich, UK
The Cambridge Audio A500 uses very flimsy heatsinks. Cranking the volume for too long will blow the output transistors.

The amp uses the Sanken SAP15 darlington transistors. You can replace these with SAP16. The outputs should be the only thing damaged, although you might also want to check any fuses.

The amp also has no speaker protection, so any faults will kill speakers :x

The service manual should hanging around on the Solid State forum. I recommend grabbing it if you're going to attempt a repair. If you're not sure what you're doing, Richer Sounds will repair the amp, but be warned they are expensive and IMO, the amp is not worth it.
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