Sparton 16A211 Width Problem

[Steve McVoy]

James, here is what I've found in reply to your excellent suggestions.

Is the optional R158 which is parallel with R157 present? (This circuit should be either a single or a pair of resistors. The set should have either two 11000 ohm two watt resistors in parallel or one 5600 ohm five watt resistor. (It us easy to misread the schematic here if one missed the check-parts-list symbol! These resistors provide screen voltage for the 6BG6's.) --- Yes, both resistors are there. I've removed one (lower width) and shorted out both (B+ directly on the screen grid, greater width, cathode current close to normal).


Check R178 for value. It is off the high side of the R-G-B balance controls. (It is not shown on your schematic, so I've added a complete schematic to this post.) --- I've checked it.

If your CRT is weak, has someone set the R-G-B balance controls excessively high to compensate? Are the three .022 caps off the wipers of R-G-B balance controls leaking? --- The CRT is excellent. There is no difference in width in any position of the R-G-B balance controls, so I think that rules out leaky .022s.

Since a prior owner had extensively worked on the set:
Is the yoke a Sparton XD-2071-J or RCA 223D1?
Is the flyback Sparton XD-2166-J or RCA 240 T1?
Since that flyback has so many unused terminals and may be a replacement, did you check to see of the correct terminals were used? --- The yoke that came with the set is a Sparton, but I've tried a RCA replacement, with identical results. I think the flyback is the original Sparton - there is no evidence of it ever being removed. I don't have a spare, so I can't replace it. I've checked the connections.

Have you verified that the voltage on the on the HV regulator grid is within the specified range? --- Yes, and I've removed the cap to the regulator tube to isolate any problems in might cause. Voltage is just 20kv with the regulator out of the circuit.

This week I will take a fresh look at it, after having been away for a few weeks.