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John Robertson John Robertson is offline
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Default A solid state replacement for the lowly 2D21 Thyratrontube...(sorry for the On-Topic post!)

On 2021/04/21 11:14 a.m., John Larkin wrote:
On Wed, 21 Apr 2021 10:28:02 -0700, John Robertson

In my field of arcade repairs we run into older jukeboxes - one
particular model which uses the 2D21 tube and was from about 1954.

I have the spec sheet he

It would be fun to make a solid state replacement for it as nothing
seems to exist. These tubes are still available from several sources,
but they get wonky with age.

Being able to simply wire in a TRIAC or SCR (with appropriate bits of
electronic glue) to remove this tube from the suspect list when
servicing this classic Seeburg V200 jukebox would simplify future
servicing. I always like to make things easier for the next tech to work
on machines that passed through my shop...

I should point out that Seeburg only used these 2D21s (three 2D21s used)
on their very first control center for their Tormat (200 x magnetic
cores) memory and dropped it like a hot potato. There were numerous
service bulletins culminating in the factory providing a low cost
replacement for the control centers that used 2D21s (three of these) and
the replacement used a single 2050 tube and was a very reliable design.
Not everyone took advantage of the program and all these replacement
were used up long, long ago.

John :-#)#

Got a schematic? It might be easy.

A fairly recent scan (not tidied up) of my files section for the V200
Control Center:

Relevant schematic is on page 5128 (pg 16 or the PDF).

The first control center is the original TSR1-L6, later it shows the
replacement control center the TSR3-L6.

You can ignore the stepper section, that is the interface to allow booth
boxes (called Wall Boxes in the industry) - but it doesn't matter unless
one is using those remote selectors...

Thanks for looking at this!

John :-#)#
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
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(604)872-5757 (Pinballs, Jukes, Video Games)
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