I got a B&K 440 CRT tester from an eBay seller and tested the picture tube in my Zenith TV Radio Cobramatic console. Although it tests on the low end of good the tube has good cutoff and should produce a reasonable picture. Unfortunately the flyback is bad. The Zenith part number is S-17233 in case anyone here knows of one that might be available.

Here is the youtube video I posted.

http://youtu.be/CsaIEpoIg1A

Did you check the fuse? It's not uncommon that these sets lack high voltage, so don't write off the flyback just yet.

I wouldn't condemn the flyback either, just yet. Lots of them, the outer coating will break up and crumble off, yet the transformer is still usable. Pull the cap off of the horizontal output tube, and see if you have voltage at the cap lead, and yes also check for a fuse in the horizontal output circuit, probably fusing the cathode of the horizontal output tube. You could have a bad damper, horizontal output, or horizontal osc tube causing the no HV condition, and also one of those could very well have blown the fuse. If the flyback is still usable, break off the loose pieces of coating, and coat it with some high voltage dope, or even maybe use some silicone seal. After watching your video on you tube, I would say that they flyback has at least a 50% chance of being usable.

Did you check the fuse? It's not uncommon that these sets lack high voltage, so don't write off the flyback just yet.

Thanks for that thought. Bob Andersen also said that Zenith porthole flybacks often look bad but still work so I have not given up yet.

I wouldn't condemn the flyback either, just yet. Lots of them, the outer coating will break up and crumble off, yet the transformer is still usable. Pull the cap off of the horizontal output tube, and see if you have voltage at the cap lead, and yes also check for a fuse in the horizontal output circuit, probably fusing the cathode of the horizontal output tube. You could have a bad damper, horizontal output, or horizontal osc tube causing the no HV condition, and also one of those could very well have blown the fuse. If the flyback is still usable, break off the loose pieces of coating, and coat it with some high voltage dope, or even maybe use some silicone seal. After watching your video on you tube, I would say that they flyback has at least a 50% chance of being usable.

Thank you. I will be delving into the circuitry on this set soon. I have never taken on of these porthole Zenith consoles apart. I wonder if the CRT comes out with the chassis?

Slides right out with the chassis.

Awrite !! Another Porthole hopefully fixin' to be Woken Up ! Portholes RULE !!

In WI potholes rule this time of year. :D Nice Zenith set you have there Gary! Hope it can come back to life.

In WI potholes rule this time of year. :D Nice Zenith set you have there Gary! Hope it can come back to life.

Thank you Kevin. I had one in the early 1960s in my bedroom before I got drafted. I got many hours of enjoyment from watching that old Zenith porthole console. That's why I got the one I hope to restore. Gary

Slides right out with the chassis.

Thank you John. I kind of thought it did but as I say- I never pulled the chassis on one of those porthole sets. I have two Zenith porthole sets; The console in question and also a smaller table top set with a brown leatherette cabinet. I had the table top set since the early 1980s and it did work but I had not powered that set for many years now. Gary

Portholes RULE !!

I resemble that comment ;)

Gotten more compliments w/my 1949-50 Zenith 12" Porthole than I have w/all the rest of my stuff, put together. Nothin' shuts up a 2015 wiseass teenager quicker, either.

Yes, love seeing Portholes brought back to life.

Did you check the fuse? It's not uncommon that these sets lack high voltage, so don't write off the flyback just yet.

I did check the 6BQ6 B+ fuse and it is good.

I checked all the tubes related to HV and horizontal sweep and they all check excellent except for the 6BN6 Synch Seperator. One element tests bad. I suspect this is why I am not getting any HV.

I cannot pull the chassis yet as I have other work on my bench but I did test the 6BQ6 B+ fuse and all of the tubes related to horizontal sweep. The 6BN6 synch separator tube tests bad on one side so I suspect that is why there is no HV.

I highly doubt if a sync separator tube would cause a no horizontal sweep/no HV problem. Does the horizontal output tube 6BQ6 get really hot? If so, there is little or no horizontal drive to it, or also in that case it could also be a shorted flyback. Pull the cap off of the HV rectifier tube (1B3), and see if you can draw an arc with a insulated screwdriver off the lead from the flyback. If the 6BQ6 runs somewhat cool, then maybe there is a problem with the power supply, causing no B+ voltage to the horizontal stage. Also what about the horizontal osc tube, and it's components. Another thought, would be a shorted out "bathtub" HV capacitor under the 1B3/1G3 HV rectifier tube. Is there a separate fuse for the horizontal stage? Do you have the schematic for the set, and if not many times you can find them on the web for free, maybe from the early television website. http://www.earlytelevision.org/tv_schematic_diagrams_u-v-w-z.html
Also I'm sure you will have to re cap the set, which is fairly easy if your good at soldering, just very time taking.
Good luck, portholes are definitely a unique type of TV.

I think you should continue on with your restoration of that Porthole TV.
Restored and working Portholes are a treasure - they are so unique.

If your Flyback is indeed bad, perhaps someone here has a cross reference of your
S-17233 Zenith part number to a Stancore, Merit, Chicago, etc. When I restored
my 1950 Zenith porthole someone gave me a reference to a generic Flyback that
I remounted on top of the Chassis rather than below.

I highly doubt if a sync separator tube would cause a no horizontal sweep/no HV problem. Does the horizontal output tube 6BQ6 get really hot? If so, there is little or no horizontal drive to it, or also in that case it could also be a shorted flyback. Pull the cap off of the HV rectifier tube (1B3), and see if you can draw an arc with a insulated screwdriver off the lead from the flyback. If the 6BQ6 runs somewhat cool, then maybe there is a problem with the power supply, causing no B+ voltage to the horizontal stage. Also what about the horizontal osc tube, and it's components. Another thought, would be a shorted out "bathtub" HV capacitor under the 1B3/1G3 HV rectifier tube. Is there a separate fuse for the horizontal stage? Do you have the schematic for the set, and if not many times you can find them on the web for free, maybe from the early television website. http://www.earlytelevision.org/tv_schematic_diagrams_u-v-w-z.html
Also I'm sure you will have to re cap the set, which is fairly easy if your good at soldering, just very time taking.
Good luck, portholes are definitely a unique type of TV.

Thanks for your input Walt. What I no longer have (Because it went when I sold my TV repair shop business back in 1995) is a HV probe. I'll have to get one of those. All of the horizontal sweep related tubes, horizontal output tubes and the 1B3 tube check excellent. The only bad tube was the 6BN6. What I need to do at this stage is to pull the chassis out of the cabinet but that will have to wait for a while. Gary

I think you should continue on with your restoration of that Porthole TV.
Restored and working Portholes are a treasure - they are so unique.

If your Flyback is indeed bad, perhaps someone here has a cross reference of your
S-17233 Zenith part number to a Stancore, Merit, Chicago, etc. When I restored
my 1950 Zenith porthole someone gave me a reference to a generic Flyback that
I remounted on top of the Chassis rather than below.

Thanks for your advice CW. I do indeed plan to continue with the restoration. I plan to pull the chassis out from the cabinet sometime in the future when I have bench space and time to work on it. Gary

don't rule out the fly until the set is recapped and resistors checked but if you had a fly tester it would tell you , and a hv probe doesn't hurt