Philco 50-T1403 with focus problem

[dreyfoos]

That's the ticket, Don. I owe you. I reversed the focus coil leads. Huge difference – went from 0 to maybe 90% perfect.

However, the best focus then appeared to be just out of range of the focus pot at maximum CW rotation (with blank raster or video) So then, I switched from the 12KP4 (which I bought as N.O.S. from Surplus Sales of Nebraska some years ago) to the (old RCA) 10BP4 and the focus went up to 99% - but still at CW max rotation - perfection just out of reach? Any thoughts? I had previously replaced the Rider C65 (Sams R127) 100 ohm, 1W focus coil shunt. The focus pot checked fine at 500 ohms.

BTW, the HV is 8900 VDC. Koinkidentally, I had been ruminating about those focus coil leads. IIRC, I had some reason to re-solder them a year or two ago. I had red to red and green to brown. That green to brown was a clue. Now it seems very logical that there is a polarity dimension that I had not accounted for.

Roger