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Old 2nd July 2011, 10:18 PM   #1
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Default Too HIgh B+ on Simple SE V21

Just completed re-build of my Simple. I filled the volume control and previous switch holes, re-painted and hard-wired all the off board connections; choke, rectifier, etc. Didn't touch the board itself

With EL-34s and 560 Ohm cathode resistor I seem to recall I had about 490 volts B+ and 455 at the Plate (Pin 3?) with 5AR4. That's what I have for tube V11 now but V22 (the more interior one?) has 495 at the Plate. Also, the cathode resistor at the edge (R17?) got quite hot after just a few minutes test.

The way the board takes the leads from the rectifier precludes an error if even one tube is right, yes? That seems to leave a bad part, maybe C12 or 22?

Appreciate some help, please.
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Old 3rd July 2011, 01:49 PM   #2
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V22 isn't drawing much current, so you aren't dropping any voltage in the primary of the OT. Does that channel make any sound?
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Old 3rd July 2011, 02:19 PM   #3
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Since R17 got hot so quickly and V22 was abright red, I never took the amp off the bench. For all I know it quietly operated that way for a year, but I doubt it.

The 450 volt tube has a hot resistor and the 495 doesn't, it's cold. Both measue at 560Ohms on the board. Would it be helpful to take measurements all along the schematic with just the rectifier aboard?
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Old 3rd July 2011, 03:09 PM   #4
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Quote:
Originally Posted by Ty_Bower View Post
V22 isn't drawing much current, so you aren't dropping any voltage in the primary of the OT. Does that channel make any sound?
I completely missed your reference to the Output Transformer. Of course! I'll check that board connection.
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Old 10th July 2011, 05:59 PM   #5
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Quote:
Originally Posted by BillEpstein View Post
Would it be helpful to take measurements all along the schematic with just the rectifier aboard?
Sounds like a plan.

Did you try Ty_Bower's checkout here (post 5 for a Photobucket link)? I found it invaluable.

Maybe you did that already, when you first built it a year ago, but treating it as a 'new' amp now, I'd have thought it was worth running through again.

Sorry I can't suggest any more!
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