9920U - power supply repair - thyristor

Jack Rubin

I recently received a 200 series 9220U. It ran fine for about 1/2 hour before releasing a cloud of magic smoke and a shower of sparks. The failure was thyristor RT1. Finding the fault was easy but there is no hope of reading the value off the damaged part. I have a second 9920 (actually marked 9000/200) but the only markings I see on the part say "Midwest 3905", no help in finding a replacement. 

Does anyone know what value this part should have or if there is a "generic" replacement for this component?


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