Quote:
Originally Posted by Eric H
I didn't pay much attention to it because it was the Domino style and I was probably thinking it was a Mica, however the schematic showed it to be a .05@600 and most likely just a common paper cap, why they used this one odd style I don't know, maybe it was supposed to be better quality.
It's cap# 58 on the Sams, between the 6V6 Video Output and the 6AL5 DC Restoration tube, from there it goes to the Grid of the CRT.
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Sams capacitors C58 (which goes between the plate of the video output and the grid of the CRT) & C59 (which goes between screen grid of the video output and the cathode of the DC restorer) are called C168 & C171 by RCA and RCA sez:
RCA part # 72996 Capacitor-Moulded paper, .05 mfd., 600 volts (C168, C171)
(Yep! They must have been conservative 'cause they used the old spelling of "molded" )
These RCA projection sets were notorious for blooming issues with high voltage regulation, and I've heard of stories of service men intentionally disabling the DC restoration to lessen focus shift and blooming as the HV drifted when the sets got older. It seems like cutting off your nose to spite your face, but it did allow a failing CRT to remain in service a little longer. Once people started watching TV in more brightly lighted rooms, the DC restorer went the way of the dodo bird as designers no longer saw any benefit.
I suspect the HV issues had more to do with the design of the early 8016's than with DC restoration.
The RCA 630 had a similar circuit, except the 630 used a 6K6 instead of a 6V6 for video output, and it used a normal tubular .05 mfd 600 volt for these two caps.