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Default A solid state replacement for the lowly 2D21 Thyratron tube...(sorry for the On-Topic post!)

bitrex wrote in

On 4/21/2021 2:14 PM, 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

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

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.

The 1954 gear was probably designed to run on old-timey line
voltage of ~110 AC.

110 VAC went away at the beginning of the 20th century. By 1950
120 Volts was the standard. The MONIKER remained, but the voltage
has been 120 VAC for a VERY long time.

Dialing back the heater voltage on the
thyratrons to compensate for higher modern AC supply voltage might
extend their life.

The line voltage was already 120 Volts by then. You need a
remedial electrical system / electronics industry history course.

Or maybe you would simply develop enough Internet skills to know
how to use google properly.