Early RCA Horizontal Circuitry...Help!

[Chris K]

Originally Posted by Kevin Kuehn

The horizontal yoke winding is directly driven by the plate circuit of the horizontal output using that odd looking air core auto-transformer. Conventional flyback transformers up to that point used a isolated secondary winding.

Ok I’ll need to examine the schematic and look in the HV cage at its condition. BTW I built the yoke housing support you showed and tomorrow I’m going to bring up the unrestored chassis on either a dim bulb progression or on my Sencore isolation transformer/Variac to see if it produces anything on the 5” tube. After that, I think I’ll try doing it with the restored chassis and see if I can figure out what to do for the video/sound misalignment. If I can replicate your bench top rig without blowing 15KV across my chest and heart I think I should be able to align it. I have test sockets for all of the tube pinouts so working under the chassis should be at a minimum.

[Kevin Kuehn]

Originally Posted by Chris K

If I can replicate your bench top rig without blowing 15KV across my chest and heart I think I should be able to align it. I have test sockets for all of the tube pinouts so working under the chassis should be at a minimum.

Always use the one hand rule while probing high voltages. Keep your other hand away from anything grounded and stand on an insulated surface if you're on a cement slab. If your uncomfortable or accident prone wear insulating gloves. These chassis rest quite comfortably on their side against the high voltage cage so you can navigate both sides. You need to somehow fix the 5AXP4 in the yoke so it's not moving around. You can see in my photo there's a plastic insulated clamp with an aluminum band holding it against the yoke. I don't know of any source for such a clamp and I believe that came with one of my test crts.

[Chris K]

I finished getting the rig setup and it fits on the chassis just fine. I found a loose HV anode cable and soldered two alligator clips together back-to-back to finish the connection from the cage to the 5AXP4. I wish I had a small metalworking lathe so I could turn a custom connector. This anode wire at the cage end is not bare wired rather, it has a socket on the end just like the HV connector on the RCA chassis. Can't remember where I got it but it must have been from a TV with an unconventional anode HV cage connector or it's an anode extender for powering a CRT further from a chassis. The forked end that connects to the CRT fits firmly in the other end of the wire so a fork terminated anode from a TV's HV output can connect to it giving you another 18" of travel. I think my setup is about as safe as can be on one of these metal CRT TVs.

[teevee]

Do a query on "Synchroguide". If you can find the Jack Darr book on servicing television horizontal circuits, that has a great explination of how to adjust this circuit. (Start by jumpering the waveform coil)

For the more esoteric description, see: http://rca.vobj.org/RCA%20Engineer/R...ignHistory.pdf

[Chris K]

Thanks for the heads up! The flyback in the unrestored TV is open on the primary side between test points 2 and 3. If I measure continuity between 1 and 2, it's fine but it's open between 2-3 and 1 and 3. The ETF says it has one, part #75519, but who knows if they'll be able to find it.

[Kevin Kuehn]

Sent you a pm.