[drh4683]

Tim,

Make sure the pins are good on the crt. Lots of the cemented crt plugs loosen up and result in poor connections. If the filaments light in the crt, try lightly rocking the plug left and right to see if a picture flashes, if so, you need to resolder the pins of the crt, and also make sure you have good non corroded contact the crt socket. I run into this many times with the early 60s zenith b/w portables.

Should all that check ok, make sure you have good hv. If you have a probe, check to make sure you have HV in there, like around 20KV. IF you dont have a meter hold the anode about 1/4 inch from chassis, it should arc if you have proper HV. The rule is, for every 1 centimeter of spark gap = 30KV, so the arc should be less than 1 cm. Most of the zenith anode covers will dry up over the years and dont seal to the crt like they once did. It wouldnt have any effect in your case. If all this fails, and tubes are lighting then you probably dont have any horizontal drive (from the horizontal oscillator) or your flyback is toast. (burnt up flyback is uncommon though for this type of set). That set probably has a 6GH8 h. osc. If you have a 6GH8 around, try subbing it to make sure. Those things are nothing but trouble. zenith sets are known for having corroded tube sockets even if the set is perfectly clean. What I normally do is shoot some contact cleaner into the pins of all the minature tubes sockets and work the tubes in and out. IF tubes in perticular are the worst, this will cause loss of sound and video resulting in just a blank raster.

Just to note, that rappid "snapping" you hear is the vertical oscillator and is comming from the vertical output transformer. It changes the rate of the noise as you turn the vertical hold like you said. This is kind of a clue that your set will have vertical trouble once you get to see the raster!! Your picture will probably be rolling rapidly. Luckily Vertical problems are about the easiest TV fix.