Arcam A65+ high DC offset and thump sound, help please. - diyAudio
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Old 19th January 2015, 07:54 PM   #1
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Default Arcam A65+ high DC offset and thump sound, help please.

Hi can anyone give me advice on how to repair an Arcam a65+, The symptoms are, thump sound at turn on or off and very high DC offset of over 700mv in the right channel it plays fine for ten minutes and then switches off and comes back on and carries on playing. The left channel is fine.
If someone can give me advice on where I need to be looking that would be great. Thanks.
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Old 19th January 2015, 08:26 PM   #2
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If you have the DIVA A65
Check C602, C605 and RV600 both channels drawn the same.
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Old 19th January 2015, 08:28 PM   #3
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The other channel is C702, C705 and RV700
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Old 19th January 2015, 08:50 PM   #4
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Quote:
Originally Posted by JonSnell Electronic View Post
If you have the DIVA A65
Check C602, C605 and RV600 both channels drawn the same.
Am I looking for high esr on these caps?
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Old 20th January 2015, 05:52 AM   #5
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Ok I had a look c702 is reading 1mv on the + side and 9.6mv on the - side. Since c705 is flush to the board I had to read it from c724 because they are wired in parallel. It reads 600mv on the + side and 1.6mv on the - side. Rv700 reads 1.1 volts on both sides and the ohms test shows it tracking well from 0 ohms to about 80. What do think replace c705? Thanks for your help.
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Old 20th January 2015, 05:51 PM   #6
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I have some fm Panasonic caps 100uf 25v, should I put one of those in to test? The original is 100uf 16v silmic II but of course I don't have one of them. Any advice would be helpful. Thanks.
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Old 27th January 2015, 09:28 AM   #7
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So I finally found and repaired the right channel, but now I have noticed a problem with the left channel. At switch on there is a slight thump. Putting my probe on the output terminal. I have noticed as soon as the relay clicks in it reads 110mv for a second then 64mv and finally 8mv all within 3 seconds. Then of course it slowly climbs to no more than 20mv.
Also adjusting either bios pots makes no difference to the dc offset.

Any ideas?
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