Knight Cap Tester Doesn't Like Electrolytic Caps

[Tubejunke]

This began with my posting for a manual for a Knight 83YT24 so that I could properly wire in the rotary wafer function switch that the kit builder had put in upside down. I got the manual and went through the mess of disconnecting all of the wires and components and flipping the switch. NOT really a fun job. but it did bring the unit back to life.

So I ended up with a near mint condition unit that could never have been used as it was put together. A slow power up proved that the unit actually had a fairly accurate bridge for cap and resistor values and the DC leakage test voltages were all reasonably close. The problem that I have is that wax paper, or basically non electrolytic caps work fine on the DC leakage tests. But when I connect any electrolytic to the unit there is no reaction at all on the shadow angle of the "magic eye" tube. I have read that electrolytics can be more difficult to test on these units; and I know that the charge time is longer, but I could hold the leakage switch 10 min and get no reaction. I can take any of my test caps to my Heathkit IT-28 and get quick results.

I'm just not sure what would be the likely cause of this. Low B+ perhaps?? The two 10mfd 500vdc caps in the power supply checked out ok (not perfect) in that they didn't quite make it to 500v on the IT-28 leakage test. Both got a little warm after some use. I only had one new one on hand, so I changed one of them. I guess the other cap is a likely culprit and I know it should go if I plan on using the thing much. I just don't know if that one cap would cause the problem mentioned. The power transformer runs nice and cool. Just can't test the lytics.

Am I on the right track here?