On 2016/11/16 9:04 AM, wrote:
On Wed, 16 Nov 2016 09:25:37 +0000, Geo
wrote:

On Mon, 14 Nov 2016 10:38:12 -0800, wrote:

snip
The OA2WA tubes have only two of the pins connected. So power goes
in one pin and then out the other to the next OA2WA tube and so on. It
looks like there is no output from the last tube in the series. So
maybe this is why the caps won't charge.
snip

I cannot see properly from the photos - but is there a connection to
the last (bottom) regulator cathode?
I would guess it might be to chassis so "no output" is correct.

If all three glow then the voltage across each should be fine.
There is a connection. It does not go to the chassis. I think the tube
is bad. All tubes are gonna be replaced anyway.
Eric


Keep your old tubes until you can test them and be sure they are bad.
These old tubes are not getting any more common! 2D21s were always a bit
fussy and were replaced by 2050 tubes not long after they came
out...even new out of the box there were failures. Seeburg jukeboxes
used 2D21s for their early tormat design and quickly changed the design
to 2050s part way through the second year of production due to read-out
and write-in issues. I have schematics for 2D21 testers that I can dig
up (probably find similar schematics easily enough online) and post of
my tech ftp pages if there is a demand/request. The 2D21 is pretty easy
to test, if you have access to a good tube tester it will usually show
them on the Seldom Used auxiliary tube list. The 2D21s are go/no-go
kinda things.

OA2s are also pretty basic tubes. They use a conductive gas to regulate
to 150VDC. If the tube is not broken or gassy then it should be just
fine. Check the Getter flash in the tube - it should not be showing any
white powder, that is a tube that has lost its seal and oxygen has
entered...

John :-#)#

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