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Originally posted by Helmholtz
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C32, C33 and R7 are no longer on the board. Measure DC to ground at the D7, D8, C32 junction? Okay to dial up to full voltage on the variac (while monitoring current)?
Tubes are all removed also.
Thank you
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You need to have a reservoir cap in to measure max. B+. Use any at least 500V rated cap in place of C32 having a capacitance of at least 10µ.Originally posted by misterc57 View Post
Measure B+ at full mains voltage in standby mode.
Or just measure the ACV at the HV secondary and multiply be 1.4.Last edited by Helmholtz; 02-15-2021, 09:57 PM.- Own Opinions Only -Comment
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I have a 5150-ii in at the moment. I realize they are not the same, but I think the PTs are the same. Plate voltages were right at 483. I'd be skeptical of using 500V rated caps, especially in an unloaded condition as the voltage won't be pulled down to the normal working voltage.
Looking at my old records, I fixed a 6505+ 112 combo and had the same caps fail. I used B43541B7107M000.
https://www.mouser.com/ProductDetail...nVe9U9Dw%3D%3DComment
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Why cheap out for marginal caps when the right ones are available?Education is what you're left with after you have forgotten what you have learned.Comment
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Good news, the amp is now working after replacing C32, C33 and R7. The height of the new caps are right to the top of the chassis.
If anyone is interested R7 is seeing 515 VDC on Stand By. Off Stand By it drops to around 470 VDC, if I recall correctly, I did not note it.
Thank you to everyone for the help, much appreciated!
MC
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