Sparton 16A211 Width Problem

[Steve McVoy]

The waveform on the sine wave coil is correct. Turning the hold control to either extreme makes no difference in the width. c124, r147 and c127 have been checked.

I've owned the set for a couple of years but am just getting around to restoring it. There is evidence that the previous owner had the same problem, since many parts in the horizontal circuit have been changed and a few were partially removed. C131 is not an electrolytic, and I've changed it. The cathode resistors and the pot have been checked. The -130 v line is clean, with little hum. I've also tried adding additional filtering on all supply lines with no effect.

I don't have a spare flyback, and they are impossible to find, so I'll probably end up with no screen resistor and live with it.

There is a problem with the RF HV power supplies in some 7 inch black and white sets that seems to be related to accumulated moisture in the RF transformer. I've never heard of such a thing with flybacks, but could that be a possibility? I mention it because this set has probably not been operated since the mid 50s.

It will be a couple of weeks before I get back to this.