Oscillating CJ PV-5 - diyAudio
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Old 21st April 2010, 09:29 AM   #1
batsong is offline batsong  United States
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Default Oscillating CJ PV-5

Hi. I think this is my first post.
I am having a bad problem with a Conrad Johnson PV-5.

It started to rustle badly in the right channel, so started wiggling and swapping tubes, and moving the pots and selectors around to try to fix/find the source of the noise. Then the rustling got louder and spread to the other channel. I then noticed that the 5751 and the 5965 were switched in the phono stage and that the phono stage would oscillate badly when I turned up the volume. I tried changing some of the diodes on the power supply, as I have had these go bad before. When I turned the preamp on again,a bad hum had joined the party, so I changed the diodes back. No change.

Now I have a humming, badly oscillating preamp that rustles.

Any ideas?
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Old 21st April 2010, 01:49 PM   #2
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Have you changed your caps? That is what happened to mine.
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Old 21st April 2010, 08:13 PM   #3
batsong is offline batsong  United States
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Thanks,
No caps have been changed. Maybe I'll start trying to isolate the culprit(s). What kind did you use? I see that Jantzens might be a good deal.
-Gabe
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Old 21st April 2010, 08:49 PM   #4
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I replaced them years ago b4 I was really into DIY. They came from CJ. They were the electrolytics in the PS
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Old 22nd April 2010, 01:51 AM   #5
batsong is offline batsong  United States
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The hum was a PS diode, and it looks like the restof the trouble is caused by the relay switch that lets the preamp warm up before starts operating. Is there a way to bypass this relay? It has been cleaned before, and even still it only worked in one channel. I would like to get rid of it.
Thanks
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