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Problem with Copland CTA 401 phono stage

66.130.241.38

Hi
The right channel of my Copland CTA 401 is not working. First I have the schematic, very easy to find in the web, http://www.audioamp.republika.pl/schematy/cta401.gif , but there is no value for the components and it's difficult to identify some little caps. Also on my board I dont have R48. Secondo when I made some comparative test between left and right channel I have very different result. When I test voltage on R8 on left chanel the result is ok around 260 volts at the bigining and 130 volts at the end. On the right channel I have 260 volt at the bigining and 255 volts at the end. No real drop. R8 is OK I have change it. C5 is also ok. and tubes are ok.
Any suggestion for this problem
Thanks
PAscal

Follow Ups:

RE: Problem with Copland CTA 401 phono stage - Blackdog 12:48:55 01/19/15 (2)
First of all, try another tube for V2. It appears one side is not drawing current. Don't assume your tubes are ok even if they test good on a tester.
Check R9.
Second R48, should be a jumper if it isn't there.
Third, you seem to be grasping at stuff. It may be time to get some professional help. That repair should be under $100.00.
Dan Santoni
- RE: Problem with Copland CTA 401 phono stage - pascal 17:21:23 01/19/15 (1)
  Hi
  This is not a tube problem, I have test them and put good, but cheaper, tube when I do test. I will check for R9.
  Pascal
  - RE: Problem with Copland CTA 401 phono stage - Blackdog 17:43:18 01/19/15 (0)
    Check also the grid of that tube (pin 2 or 7). It should be zero volts dc.
    Dan Santoni
RE: Problem with Copland CTA 401 phono stage - Caucasian Blackplate 11:56:04 01/19/15 (0)
Swap tubes.

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