Smashup Volatges Off 1 Side [resolved]

[Paul Birkeland]

+reg  (A side) 2.5V = .92V, 1.1V

You should recheck all voltages.  What voltage are you getting out of the filament regulator board?

[galyons]

These voltages are different than I got when I posted 3 hours earlier.  I was getting 4.35V from the output of the filament regulator board.    Back to not so good!

Here are the voltages:

Line =120.3VAC

I to board ground =7.1V
O to board ground =3.3V

L200C pins to board ground
1 = 7.1V
2 = 3.3 V
3 = 0V, continuity to ground
4 = 2.2V
5 = 3.5V

IA   180-220V  = 204V, 204V

OA  150V ± 1%  = 150V, 149.4V

+reg  (A side) 2.5V = 0.89V, 1.1V

IB   150V ± 1%  = 150V, 149.4V

OB  45-75V  = 130V*, 58V    * ranges  between 127V and 133V

Kreg (B side) 3-5V = 4.7V, 5.0V

Breg (B side) 150V ± 1%  =150V, 149.4V

+reg (B side) 150V ± 1%  =150V, 149.4V

B1 0V= 0V
B2 150V= 150V
B3 3-5V= 4.7V
B4 0V= 0V
B5 150V= 149.4V
B6 3-5V= 5.0V

Cheers,
Geary

[Paul Birkeland]

Well, you have adequate voltage going into the board now, so that's a good start.

The regulator is set to put out about 4.2V, so your regulator is still not working.  There isn't any reason to muck around with the high voltage side of things before your tubes are properly heated.

Try pulling both tubes, then recheck the output of the regulator board.

Do both OB voltages measure at 130V, or is it one side is 130V on OB and the other side is 58V?

-PB

[galyons]

Well, you have adequate voltage going into the board now, so that's a good start.

The regulator is set to put out about 4.2V, so your regulator is still not working.  There isn't any reason to muck around with the high voltage side of things before your tubes are properly heated.

Try pulling both tubes, then recheck the output of the regulator board.

Filament reg board, no 4P1L  tubes :
I  7.1V
O 7.5V

Do both OB voltages measure at 130V, or is it one side is 130V on OB and the other side is 58V?

These voltage vary from time to time, but, yes, there is consistently  an approximate 2:1 voltage differential at OB on each side.
Current measurement is: 150V, 77V

[Paul Birkeland]

Repeat the regulator board voltage measurements with the left tube in, then with just the right tube in.

-PB

[galyons]

Filament reg board, 1 X 4P1L  tube per side:
I  7.26V, 7.26V
O 4.26V, 4.21V

Regards,
Geary

[Paul Birkeland]

OK, so this convinces me that your regulator board is probably working OK.  Do you have more than two 4P1L's?  It's possible that one may be internally shorted somehow, and dragging the output of the regulator down?

Luckily, we have a current limiter on the filament regulator board, so you won't burn it up by loading it down too hard (but the delivered voltage will drop!).

-PB

[galyons]

Hi Paul,
I switched sockets with my original pair and the lower HV reg board voltages followed.  So, yes, maybe an issue with the tube.   I put in a new pair of 4P1L's, same HV & LV issues.  I tried my 3rd and final pair, all voltages are pretty much "spot on", other than +Reg A and the 4P1L heaters.  The 4P1L  filament regulator measured:

I = 7.1V
0 = 2.8V

The rest of the measurements at the boards are:

IA   180-220V  = 204V, 204V

OA  150V ± 1%  = 150V, 149.4V

+reg  (A side) 2.5V = 1.1V, 1.3V

IB   150V ± 1%  = 150V, 149.4V

OB  45-75V  = 53V, 57V   

Kreg (B side) 3-5V = 4.7V, 4.9V

Breg (B side) 150V ± 1%  =150V, 149.4V

+reg (B side) 150V ± 1%  =150V, 149.4V

Cheers,
Geary

[Paul Birkeland]

It's possible that feeding the regulator board with mostly AC (from the disconnected capacitor) damaged the regulator.  It might be a good next step to replace the L200 chip.

-PB

[galyons]

Thanks Paul! That did it!  All readings in spec, (getting 4.1V out on the filament reg board ),  except  +reg  (A side) 2.5V = 1.1V, 1.3V, still low.    You haven't commented on the +reg  (A side) being low, so I am assuming it is OK?


I am still getting about 3-5mV of hum at the outputs. I will work on that in the next day or so!

Thanks for your help and patience.

Cheers,
Geary

[Paul Birkeland]

If you aren't getting 2.5V out of the 431 chip on one side, you can try replacing it. 

-PB

[galyons]

If you aren't getting 2.5V out of the 431 chip on one side, you can try replacing it. 

-PB

Actually not getting 2.5V out on either board, (+reg  (A side) 2.5V = 1.1V and 1.3V).  Should I replace both?

Thanks,
Geary

[Paul Birkeland]

What are you getting from OB on each board?

[galyons]

Paul,
OB is 47V & 50V.

Cheers,
Geary

[Paul Birkeland]

Did you cut out the HLMP diodes when installing your Smash-up?