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

John Robertson · 2021-04-21T17:28:02+00:00

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 here: 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 :-#)# -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) "Old pinballers never die, they just flip out."

Apr 21, 2021 44 Replies

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John Robertson 5 years ago

Yes, that might work - at least as a starting point. Need to poke at the values a bit and keep the patent design in mind too - I suspect the sensitive gate SCR didn't exist then.

Thanks!

John :-#)#

(Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out."

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bitrex 5 years ago

Could use an optocoupler to level-shift the trigger pulse and a PIC...that's not much fun either, though...

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Bill Martin 5 years ago

Nah, they are just xenon-phobic :-)

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DecadentLinuxUserNumeroUno 5 years ago

bitrex wrote in news:hYegI.69395$ snipped-for-privacy@fx45.iad:

Your pschologist attitude is not matched by your education. Stay out of the personal assessment opinion crap.

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bitrex 5 years ago

Have you given your inner child a hug today, though

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