20-02-2019, 07:05 PM
(20-02-2019, 05:56 PM)ppppenguin Wrote: Let's try a simple approach. Use a couple of silicon diodes (1N400x) to substitute for the old MR2. The ends with the band are connected together and to C31 etc. Reconnect the caps and resistors. Conenct a voltmeter to C29 so you are measuring the actual filament voltage. Switch on. If it's between 1.2V and 1.4V then you're OK. No more work needed. If it's over 1.4V switch off. If it's over 1.8V switch off ***** quickly.
I could put 2 diodes in and bring the mains up slowly on the variac whilst monitoring the LT voltage!
Lynton
