120V to 220V higher readings, 2nd problem noticeable hum both channels

[Jimb0]

I assembled a S3X with C4S upgrade wired for 120V. All voltages checked out fine. However, when I modified it for 220V I am getting higher readings. I assume the voltages would be cut in half but a few of the terminals are now reading higher. Other terminals seem to be ok. Using 120V AC line voltage

2 is reading ~250V
OA and OB are reading ~250V

I resoldered all the wiring on the main transformer but still got the same readings

[Paul Birkeland]

These issues are not from your rewiring of the power transformer wiring unless you have many, many other voltages that are all out of whack.

What are you getting a terminals 3/17?

Can you carefully measure the DC voltage at pin 9 on each tube? 

It could also help if you posted photos of the build if the problem is not immediately apparent.

[Jimb0]

I rewired it back to 120v to retest the voltages. Everything checked out normal. Wired to 120V, pin 9 read 2 or 3 volts

[Jimb0]

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[Jimb0]

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[Paul Birkeland]

I rewired it back to 120v to retest the voltages. Everything checked out normal. Wired to 120V, pin 9 read 2 or 3 volts

Is that in the 220V configuration?

[Jimb0]

That's in the 120V configuration. I'm going to try the 220V configuration today and check it again and post my readings

[Jimb0]

Tested it on the 220v configuration again.

2   243v
3   3v
4   0v
5   0v
6   249v
7   263v
10 260v

Pin 9 A/B   2v

16   159v
17   4v
18   0v
19   0v
20   241v
21   261v
24   257v

H2, H5   +2v
H4, H7   -2v

[Paul Birkeland]

Can you do the test on page 35 and let us know what you find?

[Jimb0]

4v at 7 and 9
103v at 11 and 12

[Paul Birkeland]

What is your incoming AC line voltage?

[Jimb0]

120v

[Paul Birkeland]

OK, so why are you wiring your amp for 220V of incoming voltage? 

[Jimb0]

I built this for a customer who lives in the UK and don't have a step-up transformer to test it. I could get one if that's what I really need but I thought the voltages would come out lower not higher on some of the readings

[Paul Birkeland]

Yes, you need to use a step-up transformer to test the amp once you've wired it for 220V.  Without adequate heater voltage, the tubes won't conduct, so most of the voltage readings are pretty meaningless.