1959 Zenith D3004W-Space Commander 300

[Jeffhs]

Originally Posted by ZackN920

Hey y'all, where could I find a schematic for this set? It has the "Super H20 Chassis" in it. I dont know at the moment if there's a more specific chassis identification code or not, just let me know if there is and I'll see about pulling the tv out of the corner to have a look.
General gist is that the set seems to be developing issues, and I'd like to turn it into a daily driver. I also got to get it apart sometime to give the flyback some attention. Last time I took a peak at it, it looked like all the black coating fell off and was laying in a pile of chipped off pieces. (Mabey the reason it sounds like a burning cigarette with the back off)
I've got more I could add but I'm out of time

Sounds to me as if the CRT is shot. The black coating flaking off the bell of the tube (the aquadag) acts as a huge capacitor in the high voltage system. Without it, the CRT cannot get 2nd anode voltage, which will of course kill the raster.

I'm not sure where the sound you're hearing is coming from, but it seems to me that the missing aquadag on the bell of the CRT may have a lot to do with it. In any event, the tube is now little more than a glass jug and must be replaced.

[jr_tech]

Lost dag on the exterior of the CRT can easily be washed off and re-applied... The CRT may be ok... more testing is needed before counting the CRT as "shot".
The dag is used as a filter capacitor for the HV supply, but its absence will usually just cause more AC "ripple" on the HV... HV is likely still present, and likely arcing, perhaps to the flakey dag or from the flakey dag to the chassis ground strap.
But it really sounds as if the flyback not the CRT is the source of the black flakes?

jr

[Radiotronman]

I also have a h20 zenith space command. I'll look and see if I have the schemstic for it.