s-petersen
Scott
That would be the easiest way.Are the voltage test points on the bleeders close to spec?
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Heathkit PS-4 exhibits snarky behavior
- Thread starter thorpej
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- 6l6 heathkit power supply regulated
The B+ sags a bit with 13K load, but not terribly much, do I think the diodes are OK. The bleeder test points are tricky, because I can't get it below 100V with the pots set according to the test procedure. However, I think I might have spotted a wiring mistake made by a previous owner, so stay tuned.
Ok, yes, it seems there was a wiring mistake made by a previous owner. The negative terminal of C1 (the screen filter dual-cap) is supposed to be connected to the 6L6 cathodes. But whoever assembled it tied it to the same tag strip terminal as the junction of R9 (the 1M grid resistor of the 6BH6) and the B+ adjustment pot wiper. It's supposed to be on the next terminal over on the same tag strip.
I fixed that and it behaves much better. Adjustment is nearly instantaneous, and the jump when the B+ is turned down has disappeared.
However, there's still a problem. I can't get it adjusted below 100V and the 6L6 screen voltage (relative to the Common is way higher than it's supposed to be, so I suspect there's another problem lurking in there somewhere.
I fixed that and it behaves much better. Adjustment is nearly instantaneous, and the jump when the B+ is turned down has disappeared.
However, there's still a problem. I can't get it adjusted below 100V and the 6L6 screen voltage (relative to the Common is way higher than it's supposed to be, so I suspect there's another problem lurking in there somewhere.
I figured it out. I was trying to get the voltages to what the manual states with the trimmers at a specified setting, so zero-trim all the way clockwise should be +40V, but was +100V. Determined that R11 (the 680K resistor that connects the zero-trimmer to the voltage adjust pot) had drifted upwards way out of spec -- it was reading 790K. Replaced it with a new 680K resistor (that read at 679K), and the voltages fell right in line with the spec when being fed with my variac set to 117Vac.
Did the calibration procedure (requires a few iterations), and now it has the full 0-400V range without any hiccups whatsoever. Cool. Even with my variac set to 124Vac (which is what my line voltage is most of the time) it is still dead on with no additional calibration necessary.
Confirmed that the voltage doesn't even hiccup with clipping in-and-out a 13K 10W resistor at a few different voltage settings.
So, it seems to be working great now. Thanks for the help, folks!