Hey Everyone!
I had an account here years ago, but it seems to have been deleted from inactivity I guess.
Excited to finally get got hold of a Sony BVM, It was cheap enough but that's because it doesn't power on at all.
Very quickly evident in the power supply that the protective thermistor TH1 and resistor R92 have got very hot and blown themselves to pieces. And it looks to me the reason for this is the rectifier network capacitor C81 has gone bad.
My question is obtaining a suitable replacement for the Thermistor that will continue to provide the right protection. The manual specifies Sony part number 1-800-820-12 and Sonys official part website shows 1-800-820-00 & 1-809-531-11 as useable alternates but none are in production anymore. And I can't find any information on what the exact spec of this thermistor was. Is there a way I can work out what would be suitable based on the circuit?
Many thanks in advance
The service manual power supply schematic
https://archive.org/details/bvm-1410-pm-sm-sony-service-manual-en/page/n119/mode/2up