New build won't pass voltage checks.

[bubba_pa]

Completed build.  Line voltage in 122 V.  Passed glow test.  All resistance checks within specs.  A side voltages good.  H2, H5, H4, and H7 all good.  B side not.  Got first set and rechecked connections.  Fixed B8 (poor connection).  Readings as follows:
   
    Before fixing B8      After fix B8
      16    63 V                  77
    *17    <1 V                38
    *18    <1 V                33
      19      0 V                  0
      20    312 V              354
      21    325 V              371
      24    240 V              325

Careful inspection I don't see and bulging caps.  Solder joints look good.  Had also attached the 8.2 ohm, 1W to 21U and 22U, not lower. Checked before reinstall and still in specs.  Moved to correct location, no change.

The B side 680 ohm, 3W does look like it might have gotten hotter than the A side companion.  Haven't pulled it out to check yet.

I have limited internet access and can't seem to get photos to load

 

[bubba_pa]

Trying photos again

 

[Paul Birkeland]

18 and 19 connect together with a 249K resistor.  I see that it's there, is it well soldered in?  17 and 18 do not connect together but seem to have the same voltage.  Are you sure this isn't something like 33mV instead of 33V?

It can also be a good check to swap tubes between sides. 

Do you have additional photos/angles of the build? 

 

[bubba_pa]

Thank you for response. I will check 18 & 19 and the resistance.  I had seen some confusion of mV with V before so don’t think that was it, but will recheck as I am very new at this.  Will also swap tubes and recheck.

Other pics.  If something specific needed, let me know, can try to get.  Thanks again.

 

[Paul Birkeland]

If this resistor is out of position, that would explain at least one of the spots where you have 30V.

 

[bubba_pa]

will also check, but pretty sure 19L to 25L. 

 

[bubba_pa]

Good troubleshooting from afar.  Swapping the tubes around gave me the answer.  Problems switched sides as well.  At least I know that the soldering isn't the problem.  My faith is restored.

What is the easiest way to obtain a replacement tube?  Through you, or open market? 

Is there any problem with pulling the bad tube and running it as a mono amp?  I'm kind of anxious to at least hear something.

Thank you again for helping to solve the problem.  I am off line until tomorrow, and will check then.

 

[Paul Birkeland]

You can e-mail replacementparts(at)bottlehead(dot)com about this issue.  Be sure to provide your name, order number (if possible), and a link to this post.

-PB

 

[bubba_pa]

Thank you.  Much appreciated.