I would like to ask for any helpful hints with bringing my Zenith Model 5111 going again. It has the 25LC30 chassis. I posted some explanation of it in another post, but basically got no input. I was not necessarily asking for help at that time though.

The CRT is a Sylvania rebuilt. I am worried becuse somewhere I read a post by someone thinking that Sylvania rebuilt CRTs were trouble. I have no way to check the CRT at this time. Also, what is the deal with the horizontal output tube and the possible need for adding a fuse. Unfortunatly, I have powered the set up with the horizontal circuit in action, and it smoked both times. It smells like a resistor, but I have not seen anything fried at this point looking through the wonderful access panel on the bottom. Way to go Zenith!:thmbsp: I just hope I didn't hurt anything like the flyback.

I owned several old color sets back when they weren't quite so old and I worked on them what few times they ever needed repair. With this set, the approach is not going to be as simple as maintenance. The set has simply been dormant too long. I would like to get a picture going so I can get an idea of the CRTs condition. I don't want to replace all of the caps and find out that I have a bad CRT. A tester would really be the way to go. Actually, if they make one that does both the older B&W CRTs and the 60's-70s color stuff, that would be perfect for me. Also, I already know the whole thing about changing all of the capacitors and bad resistors as far as expecting a set to be an everyday performer. I have been messing with old B&W sets on and off for almost 30 years. I just thought perhaps there are some Zenith color enthusiasts here who might have some tips more specifically relating to early Zenith color sets.

Thank you all! :thmbsp:

I think any CRT tester that handles color CRTs from the 70's will handle most any earlier B/W crt.

John

I would start by checking for bias voltage on the horz out tube.

also monitor the horz out cathode, if it starts to soar then shut down and firgure out why.

check the resistance readings on the fly.

I do like to install fuses for one thing it makes the horz out current check easy, not to mention I hope it would pop before any damage is done due to a tube failure.

example I use a 310ma on a hot that draws 220. I have seen the current soar when the horz osc was not installed (simulate a burned out tube).

I also like to install fuses on the B+ again just a bit over max (750ma on 500ma B+) the current tends to come up slowly, so you can be conservative on fuses (both B+ and cat)

Thanks Dave, I need to locate a schematic that hopefully includes transformer winding resistance values for the flyback, and I need the bias voltage along with other voltages. I am really spooked that perhaps I have damaged the TV. Somewhere I have read that you should remove the HO tube when slow starting an old set with a variac or for me the 100W light trick. Not as effective, but better than nothing. So, I ran the set for several hours at the reduced voltage and no tube. You mentioned that no tube causes damage and I know that other high current issues cause damage so I am guessing that the damage would mainly be to the flyback.

It is when I added the tube that problems became evident. The first time I powered it up the tube was glowing red (obviously something causing a high current draw) and there was smoke that smelled like a resistor. So the was not really operated at full potential with NO HO tube. And when it smoked I did not operate it for more than a few seconds. Now I did take the cap off of the HOT and let the set work a while because there is no smoke or red hot tube with the cap off. Hopefully I did no permanent damage to more than maybe the HO tube itself.

Operating without horiz. output is OK, what is harmful is having the tube in place
while the oscillator tube is pulled out. Good luck with your project!

I generally pull both the HOT and the VOT for the 1st power up. I have not heard about the VOT but figured same deal, its not going to osc at reduce voltage, so why stress the vert out trans.

With both those tubes out powr up slow while monitoring the B+ voltage and current.

If this all passes and the filter caps stay cool, then you pop the HOT and the VOT back in. do a power up again checking the B+ and current, and the cathode current of the HOT now that its in the circuit.

It sound like a bit much but better than taking a chance.

Like the other poster said the HOT in and the Horz osc out wil for sure cause an issue since the HOT relies on the horz osc for bias, with out it the the tube will red plate very quickly. this is why I like the fuse on the HOT cathode, just in case the horz osc quits for what ever reason (burns out, open screen, anything).

Regarding the crt, I have had worse luck with Sylvania picture tubes than any of the other major brands. They look good when they are strong but just don't seem to live as long. That's just been my experience.

Good info, thanks again everyone. So, I need to find a CRT tester basically. I say that because if this Sylvania (rebuilt) CRT is one of their bad runs, then the project is a boat anchor. I am hoping that the set got the newer CRT during it's last couple of years of service and Sylvania or not, it will hold out for a while. If the tube is good I think the set is worth the time and $ involved in circuit repairs. Both a CRT and re-cap job to me would just be beyond reason for what I guess is a fairly common old Zenith 5111. I took the set in, mostly to save it from possible landfill duty.:sigh: I have five other sets that need restoration to varying degrees! So, hopefully I will see some signs of life pretty soon. Maybe it will be a keeper! I think the Zenith is a nice looking set that is not too bulky. It certainly could not be more plain if it were a Muntz!:D

I dont think any roundie would be considered common, so its def a keeper.

Did not realize it was a roundie.

I actually prefer the Sylvania tubes for their color. I would also check for a shorted high voltage rectifier loading down the horizontal. I have been caught by that more than once.
That can be a sweet set when finished. I love the metal cabinets!

The metal cabinet ones aren't common at all, finding this one is a great save. I've also never had any problems with Sylvania CRTs, just Channelmaster. I like the Sylvania "Color Bright 85" rectangular tubes as well, gorgeous color on those...
I look forward to seeing it up and running!

So, it seems that I might have a good one! Cool! I wasn't sure what to think of the Zenith with a metal cabinet. I knew that I liked the lighter weight and it helps to not to have electronics AND wood to worry about. The metal cabinet is in great shape; I was just worried that such sets might be seen a second rate or junky. I am sure that a metal cabinet set with a single speaker and no "Space Command" was a base model when it was new.

Also, I was pleased to see someone comment that Sylvania rebuilt CRTs are not some kind of nightmare CRT like the dreaded 19AP4 metal/glass black and white CRT used in the forties and early fifties. They just lost vacuum well after their normal life expectancy had passed. They were fine for their time. So, when I get a chance (hopefully soon), I am going to do a capacitor check in some critical areas that I have in mind. I already know that they it is best to replace all caps except ceramic discs. However, that does not mean that they are all bad by a long shot. They just could go bad at any moment. It has been my experience that paper capacitors are much more likely to be bad from the get go than electrolytics' in a long dormant set. I think I have heard opinions to the contrary.

Either way, I am going to try to do a little patchwork to see what I have here. I can't do much deeper repair until I get a Sam's. I was hoping someone here might have one somehow scanned into something like a PDF file. That would be really cool! If somebody has hard copy, that would be great! Of course I will cover any expenses if anyone can send me a folder or schematic.

Zenith Model 5111 Chassis# 25LC30

I haven't got any technical advice to give in regards of your Zenith but thought I'd say I really dig your avatar, Blue Cheer totally rock man!!!!! Vincebus Eruptum is an awesome album!!!

Best of luck with your restoration on your Zenith roundie.

Hold up on the caps, unless they are wax paper types there is a good chance they are fine. I love the handwire chassis of the zeniths, BUT there is a lot of stuff under there, layers at times. I prefer PCB's to work on for that reason alone, a lot easier to lift a leg and check a cap. The problem with shotgunning caps is you may introduce a problem esp with handwired chassis.

Watch out for any parts that are connected to coils, I pig tail new parts there to avoid stressing out the coil with heat and movement needed to remove the old part.

My recommendation would be to check the few HV tube caps, prob in a white tube, with a good HV cap tester (check for leakage under load) or just go ahead and replace those prob only a few, like in the vert circuit, maybe around the crt screens. Replace any paper caps (if it has them). Check small eletrolytics. check the can caps for shorts (lately I have had good luck on them being just fine).

then fire up again this time monitor the B+ for current, and pull the HOT and VOT tubes out. the current should be low since those draw a lot.

if all goes well then try again with the tube in, monitor the B+ and watch to see if it goes high as those tube start to conduct.

Prob would not hurt to check the Horz tubes and HV for shorts if you have a tube tester.

I have scanned part of the SAMS for you with my scanner. Where can I email it to to you, Tubejunke?

Page 18 of the schematic I looked at has the resistance chart. Use it.