pictures of my zenith roundie purchased from a used car dealer.low level zenith with a masonite cabinet,screw on legs,but its all there.it has an excellent crt with a very dark shadow mask.looks like crt was replaced in the 80s.it is marked "hi-lite" but the sticker is a red label zenith.produces a sharp,beautiful picture but it has a bad vertical shake issue.unplugged convergence assembly and the shake stopped.of course vertical was way off but it locked and the shake and jitter was gone.many caps are dripping wax with only 1 paper cap.owner had it serviced once in the late 80s and used until digital conversion.i rescued this set as it was going to recycler if not sold.not sure what i will do with this.my eyesight is faltering and i am not as handy as i used to be.a total recap is needed but not sure if im got it in me.the pains of growing older!

Hey Ron! That's a neat set, not fancy but a great performer. Looks like a '65. Glad you saved it from being recycled:yes:

thanks!glad i did too.need to recap this beast and clean tuner.the brightness and contrast look go between the jitters.back in the shop days,i go go through this in no time.now at my advanced age,it would take years!cabinet is not really too bad except for the top.may have to re-veneer the whole thing.this may be the elusive black matrix roundie crt.no number on the crt but the face is very dark.i have about 6 roundies and this as dark as my zenith chromacolor with the sylvania 25vdmp22.not sure without number but it could be.

If it has any of those white ceramic caps change them. I had a zenith that was shaking and it was one of those white things.

Nice set.

McGarrett's head looks like an Alien in that picture. :D

The picture with the dot interference running thru it looks just like my Zenith MC when the vertical output transformer shorted. Unsolder the convergence winding (both leads) and if it plays without the dots on the screen and the shaking stops the transformer is shorted. Also, a 2 watt resistor will overheat in the vertical output stage. Mine did it about a year and a half ago. I got the transformer from Moyers. My NC did the same about a month later. Once again moyers had the transformer.

Yeah, it needs a little TLC...But it IS still workin'...Sort of, anyway....(grin)

If you figure out the vertical issue, please let us know. My 1965 Zenith roundie, 25MC33 chassis, has had shaky vertical deflection since I got it. Sometimes it collapses to a line for a fraction of a second and comes back. Short of rebuilding the entire vertical circuit, I have not found out what is wrong with it.

My 1967 24NC31Z did the same thing. It was the vertical output transformer. I ended up having it rebuilt.

If you figure out the vertical issue, please let us know. My 1965 Zenith roundie, 25MC33 chassis, has had shaky vertical deflection since I got it. Sometimes it collapses to a line for a fraction of a second and comes back. Short of rebuilding the entire vertical circuit, I have not found out what is wrong with it.

You may have to recap the vertical stage. Because the Zenith 25MC33 chassis was made in the mid-1960s, the capacitors could be (probably are) failing. In fact, I would expect to find one or more leaky or downright defective wax paper caps in a set of that vintage.

I would start by recapping the power supply, if you haven't already done so. The entire set runs on this supply, of course, so if anything at all is amiss with the output voltages (if they are low, absent or are anything less than pure sine/square waves), you can expect problems with the operation of the set. Have you replaced the vertical oscillator/output tube? If this tube is weak, it may cause the problems you describe, although, as I said above, they are more likely due to defective capacitors or even off-value resistors.

I cannot say for certain without seeing the set, but it seems to me as if (after replacing the vertical osc/output tube) you may have no recourse but to rebuild the vertical deflection circuitry from the ground up.

there are a couple elmenco caps, HV (1kv) that are likely failing. these are the white ones mentioned a few post back. Start there. IIRC .001 and .01 but not sure.

there are a couple elmenco caps, HV (1kv) that are likely failing. these are the white ones mentioned a few post back. Start there. IIRC .001 and .01 but not sure.

they are .1 1kvolt im trying to hunt down some right now ,the ones in the barn zenith iv been restoring are leaky.

trying to get dave to come over and take a look.as i mentioned,unplug convergence assembly and jitters stop.output transformer may be arcing inside.anyone have a part number for this transformer?shame because it has full, proportionate vertical display.many of those brown caps have wax dripping out.2 white caps and 1 paper cap.dont have a sams and need some new glasses.can be used as a table model and this is exactly the roundie i had been looking for.

When I first got my set home, I found that the convergence board was disconnected on it. When I hooked it back up, I got the same symptoms as yours. I would check the vertical output transformer.

Ron, I can help if you want. PM me and let me know.

As for the vertical collapsing and recovering. It's those three legged couplates. I divided the resistance by two. Then I took two resistors half the value and bridged the cap between the resistors. It works well. I did it on the one I scored at the convention.