01-24-2017, 06:41 PM
Just finished the chassis resto on this 620 and it plays very well. Did all the cap and bad resistor replacements and had the tuning cap off the chassis for a cleaning in an ultrasonic cleaner. Reinstalled and as I said set plays well except I noticed a dead spot around 700kc area. It was scratchy there and measured low resistance between the plates. After inspecting and not finding any touching plates I figured there was some foreign material or crud in there that I can't get to. So, what I tried and had success with was I charged an electrolytic cap to around 350 volts and clipped it across the tuning cap and when I hit the troubled area the cap discharged with a spark and cleared the problem...worked great. I figured I would pass this along!
Ron
Ron