After about 22 years of 24/7 service a controller board started to have intermittent motor drive errors because the servo amp had no output drive. One of the tech replaced the motor and servo module but the problem was still there. I'd seen this before on this type of machine. The old HPR8060 SSR chips internal opto-isolation led gets so dim it won't activate the photo-transistor inside. The chip electronics had worn-out. I stocked the exact replacement parts 10 years ago when I first started seeing this issue so it was a simple replacement of cheap $5.30 part instead of a new board replacement for thousands.
Replacement part: https://docs.broadcom.com/doc/AV02-1181EN
U69
There is a funny description of the original part at adiomuseum.
https://www.radiomuseum.org/tubes/tube_hpr8060.html
Replacement part: https://docs.broadcom.com/doc/AV02-1181EN
U69
There is a funny description of the original part at adiomuseum.
https://www.radiomuseum.org/tubes/tube_hpr8060.html
