Another Westinghouse H840CK15

[trinescope]

While trying to improve the convergence last night the horizontal oscillator decided to lose lock and then went off frequency. Best I can tell is one of the mica capacitors is going bad since swapping tubes and checking resistors showed no problems there. I went ahead and ordered parts to replace all the mica caps in that circuit.

Also, the vertical centering control was having no effect, but the control had normal resistance. I checked the large capacitor on the top of the chassis and it was OK, actually measured 2200uF (marked 1000uF) with a bit of dissipation factor, but not too bad for an old part and still usable in a low impedance circuit like this. I finally found the problem, the wire going to the center tap of the centering control was never soldered from the factory and now had green corrosion. I cleaned and soldered the terminal, hopefully it will work when I reinstall the CRT.