Horizontal efficiency coil concerns
 

I may need a horizontal "efficiency" coil for my 1964 Zenith 5111. When I found the set there was no HV and the H. Oscillator tube plate was glowing red. I replaced the voltage regulator tube and the HV rectifier and had a raster. I just happened to notice on a visual inspection that this coil's winding end moved when I pushed lightly on it with my finger. I think that it should be rigid in order to be accurate, but I could be wrong as I don't know whether the mounting portion is just broken and would not effect the circuit, or if the actual inductor winding portion is loose.

I fear the latter as it seems springy to the touch. That could be the wiring. At any rate, it might be best to replace this if I need to and can find one. I know that all issues horizontal are critical in these old color sets which I am by far not an expert on. Any advice and/or help here would be greatly appreciated. Thanks in advance!

My 1965 Zenith roundie had the same symptoms, no HV and horizontal output glowing cherry red. The horizontal efficiency coil had a broken plastic coil form. After replacing it all was well. If that coil is in doubt it is best to change it. It is not worth risking damage to the flyback.

Yes, that coil is absolutely critical, as it's used to tune for the sharply defined 'dip' in HO tube cathode current. When the coil form breaks and the windings go springy, that resonant point is lost.

Wow! Great info folks and my suspicions were right. Glad I didn't get stubborn and try to put a lot of play time on the set. Of course I never would have powered it for more than a minute with a red H.O plate, but that went away when I changed out those tubes.

Enough of the story and on to more important things. Where in the world am I going to find a good coil? If anyone has an extra I would gladly buy it. and for the record I just parted a pristine Space Command (black and white) set. So if there are any early remote control fans out there wanting to do some trading, perhaps we could do that. I really want to get my set going. I also need a nice control cover door. Mine is there, but a bit tattered.

I have a parts chassis that may have the coil still, it may also be burned up if it's there. I'll check and if it's good, it's yours.

Hey thanks! Evidently these things aren't made all that well. You may have to be real tender yanking that one. Do me favor (and yourself) and just snip the wires. Then I can just re-connect to those without even heating the coil. I'll keep my fingers crossed. Thanks again!

What happens is, the inside tube of the coil form crystalizes from heat and lets go. There's a couple of (blue) coils on the convergence board that run pretty hot and have the same problem. If they haven't let go yet they will eventually.

As a proactive/ preemptive measure, it seems like it oughta be possible to bind the outer frame to prevent separation even when the inside tube crystalizes.
Maybe a few turns wound front-to-back of something like dental floss, tack glued in place(?).

I've never done it, but has anybody ever adapted the RCA type eff.coil to work in a Zenith?

You could probably dip the whole thing in some type of hard epoxy in order to preserve it and prevent the breakage. As far as adapting the RCA type I would imagine that if the inductor windings and the (what I assume to be) iron core adjustment meet the same specs, then the part would work. It probably wouldn't mount up the same though. I don't want to go that route. Just hoping for a decent stock replacement. Hopefully Zenithfan1's plan will come through for me.

I was able to get to that chassis a few days ago and I'm sorry to say, it's one of the many fried parts in the Horiz. out section. I hope you find one soon.

OK, thanks a ton for looking! I know these sets are really popular, and I know about the critical nature of strong horizontal/H.V. sections, so there must be some outlet for parts. I guess the norm is caps and resistors which we buy from distributors. I wonder where I can find this coil??

It would help if you could post the Zenith part number and any subs that Sams recommends.

Excellent idea Tim. I might just be able to do that. Should be listed in the Sam's parts section. Guess I took it for granted that since so many people are getting into early color sets that a Zenith coil would be well known. I found out that others have had them break and it caused problems.

I have a mint condition 50s Zenith remote control setup for trade in some parts for this set. I need this coil, a decorative control door, and a tuner knob (outer).

Sam's lists this inductor as part # S-62016. I'm not having much luck finding one, but with what seems to be confirmed here there is no use in proceeding with restoration work without one. As many of these beloved "roundies" as are now the rage, I would think that one will pop up eventually or really by now. I guess those that have them are using them. I am going to have to luck out and find someone who has junked out a basket case.

At this point I am regretting all of these sets that I myself junked out back in the 80s when you could pick them up for a song working fine.

The handy-dandy guide I got from Bryan a few months back lists an equivalent by Thordarson, # WC-39. eBay is your best resource for these, IMHO :thmbsp:

coil
 

Here's what a search for a wc39 yielded. Cut and paste into your browser, good luck!

http://www.remelectronics.com/Search...cturerAbbr=THO

Hey thanks, they do indeed have it listed, but listed as "contact REM" so I will have to give that a try. Probably with "roundie" color sets being the current rage and this being a common problem the supply chain is dwindling.

Slim chance you will ever find a good or NOS efficiency coil for this set. The plastic spool assembly for the efficiency coil is the exact same as any of the right side convergence coil assemblies. Your best bet would be to get a much more easily obtained convergence coil, unwind the wire off of it, and re-wind the spool with the wire from your existing efficiency coil. Its not that hard becaus the wire gauge is much thicker for the efficiency coil, so there is no worry of making a mess of the wires, plus there is no special winding pattern, just CAREFULLY follow the winding direction as you unwind the old coil so you can "recreate" the new one. I've done it before. Works perfect. Just be sure to use the original iron slug from the old coil.

Wow that's cool. I never rewound one. Was the current-dip point somewhere near midrange after the rewind?

I was at the ETF and got a 25MC33 chassis(I always liked the chassis # better from an electronics ID stand point) roundy, and there was another Zenith roundy chassis there that I was tempted to buy in the silent auction if only I was able to stay till the end. Seeing this post again I'm regretting not convincing someone I knew there to collect it for me, and I may regret it more if the HV issue in mine is bad unobtainium.

Thanks for the ray of hope MOSFET. That idea will probably help a lot of people if this is as common a problem as some say it is. However, I have often been surprised at exactly what is still laying around for sale in the N.O.S. realm. A few years ago I restored my 1950 RCA TC-127 and the power transformer was toast. I was able to find an exact replacement for that dinosaur for a reasonable price. Then I keep dreaming that as popular as early 60s color sets have become that I should be able to find someone with a spare chassis or three that would come off of one for a little cash.

My set being a model 5111 may throw some people off, but the chassis should be about as common as the come for that era. The 5111 is the metal cabinet model which are few and far between as people tossed them when they quit or when the upgraded to a nicer looking wood cabinet with a larger rectangular screen just a few years up the road. Anyway, mine is exactly the same as other 1964 (ish) Zenith color models which should be still pretty plentiful. I can't see hobbyists tossing otherwise good working sets to the side, or to scrap over an inductor. I feel like over some time something will come through here.

I just have the itch to see that thing working properly, AND with a new woman wanting to replace my junk with her junk it is easier to justify keeping when it actually works! I'm sure many of us have been down that road! :thumbsdn: SHE, not me, is the reason that the Space Command got scrapped! LOL

Yes, you are welcome for the ray of hope. Your ray of hope is to rebuild the coil as I suggested which would be just as good as installing an NOS coil. That being said, I really don't think I was blasting you with negativity to justify the sarcastic comment...

Ummm, I meant absolutely no sarcasm in your giving me a good second way of doing this in the case that an NOS or used part is unobtanium. Should have used emoticons I guess. Sorry man, but thanks the same.

Best regards,

Tube