Re: 7603 working .... then blank



+50v PSU

Firstly, a correction to what I wrote yesterday ……. not all transistors are ON (you probably knew that already ….. 😊)
Q863 is ON (e -12.5, b -11.9, c -0.6)
Q860 is OFF (e -12.5, b -12.5, c 2.6)

Dave ….. how did you calculate Ve in your Post on Feb 23??? Estimated Ie???? Datasheet spec???

Roger … in your Post on Feb 19, you stated that Q860 and Q863 have very small Vce. Can you please explain that further??? Are you referring to the voltage available between e and c of approx. 55 volts in total??? Or a Datasheet spec????


Re-tested CR875 and then removed the various Plugs and re-tested.
The ‘short’ is ‘downstream’ of P971. After removing this Plug, CR875 measured normally as a Good diode.

Not sure if this is good news or not …. as I am unfamiliar with what is ‘downstream’ …. but I guess I am about to find out ….. 😊


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