UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Scopex 4D-25 Oscilloscope Repair Help

OldTechFan96 · 16th Oct 2017, 11:58 am

I've measured the resistance between the chassis ground and the output of the voltage rails.

+20V (on pos. of C664) - just under 1K ohms.
-20V (on neg. of C684) - 1.9K ohms.
+110V (on RV604) I can't remember which terminal has +110V on it so I measured both: 15K ohms and 1.5K ohms.

Next I'll disconnect the transformer secondaries, measure the resistance between them and then power the transformer.

If there is a short to ground, what would the resistance be?

16th Oct 2017, 11:58 am	#120
OldTechFan96 Octode Join Date: Jul 2017 Location: Newcastle Upon Tyne, Tyne & Wear, UK. Posts: 1,178	Re: Scopex 4D-25 Oscilloscope Repair Help I've measured the resistance between the chassis ground and the output of the voltage rails. +20V (on pos. of C664) - just under 1K ohms. -20V (on neg. of C684) - 1.9K ohms. +110V (on RV604) I can't remember which terminal has +110V on it so I measured both: 15K ohms and 1.5K ohms. Next I'll disconnect the transformer secondaries, measure the resistance between them and then power the transformer. If there is a short to ground, what would the resistance be?