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Progress? report:
First, a puzzling observation: the 100 ohm focus coil shunt (Sam’s R127, Rider’s R65) seems, at this time, to be superfluous. No difference in the raster focus whether it’s in or out of the circuit. I subbed all the way down to 0 ohms and up to several hundred with no effect on focus. I know manufacturers aren’t in the habit of spending extra pennies for nothing. Seems significant to me – could this be the missing piece of the puzzle?
It was noticed as I was inch-worming my way through the circuitry to verify every connection and component. I have found nothing out of place so far. All electrolytics are fresh and polarity double-checked.
I also rigged up for smoother DC from my breadboard supply to the focus coil. I used two 22uF 350V’s with the secondary of a filament xmfr in between as the inductor. There’s still a ripple but it’s much reduced – appears as one or two bands instead of six or eight.
It took 30 VDC indicated on my Variac and confirmed with the VTVM to get perfecto focus using the lower ripple breadboard supply. The current measured 195mA with the digital ammeter. This same alternate supply - without the new filtering - gave perfect focus at 160mA and 33VDC.
(I’m still trying to get an ammeter to confirm what I’m now getting with the digital. I took out the meter on my old Hickok and it seemed to be moving freely once I could hold it in my hand and subject it to gravity from different directions. Now I need to check all the shunt resistors in the range circuits and then there are the contacts and connections to clean up before I put it back together.)
Don, you said, "Try a 10-20 uf electrolytic on the 5U4 side of the B+ source when measuring total TV current drain.” I’m not clear on where I should put that cap relative to the meter. Do you mean in series with the digital meter lead?
Roger
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