1964 Zenith 5111 comes to life!

[Tubejunke]

Originally Posted by ctc17

Yep, change the 3.58 crystal, its ok to use the small form factor one they sell in the blister pack at the local electronics store. Its a $2 part max. If you dont have such a thing locally I can send you one.

Is there any specific value to look for, or ask for like 3.58. I am not very familliar with crystals.

[miniman82]

Originally Posted by ctc17

its ok to use the small form factor one they sell in the blister pack at the local electronics store. Its a $2 part max. If you dont have such a thing locally I can send you one.

Not always. Some of the circuits have the crystal tied in to the plate circuit of the oscilator, and I remember Phil saying the new crystals did not like having that much voltage across them. Best to find one of the old large can style ones that can take the voltage, trick is finding one that's still good.

The CTC-9 I recently sold had a good crystal in it, the CTC-7 had to be replaced before it did anything, and the one in the CTC-4 still seems to be good. So it's hit and miss, I guess.

[old_coot88]

Originally Posted by Tubejunke

...My mention of "bleeding" may not be a very descriptive term. Basically, when I turned the color killer clockwise, I saw hints of color in odd places like the lights on top of a cop car, but black and white in most other portions of the raster. These places were the wrong color with too much amplitude.

When you see those traces of 'wrong color', is it all of one color, like green (or purple)? In any case, it sure sounds like the reference oscillator is not running.
Since you are seeing traces of color, it indicates the CK circuit is being keyed 'on' by the burst signal. If the burst signal were absent, the CK would remain 'off' and you'd see no traces of color at all.
(The purpose of the CK is to prevent colored hash in B&W broadcasts.)
Bill(oc)

[charokeeroad]

I remember that Blue Cheer album.. I was stationed in Huntsville Alabama working on Hawk Radar at the time.. nice to see it from time to time.

[ctc17]

Originally Posted by Tubejunke

Is there any specific value to look for, or ask for like 3.58. I am not very familliar with crystals.

Just ask for a 3.58mhz crystal. They come in blister packs of usually two. I doubt a radio shack would have it, it has to be like a local electronics stock. They are very common, at least at the stores around here. The local store has about 5 different brands.

[ctc17]

Originally Posted by miniman82

Not always. Some of the circuits have the crystal tied in to the plate circuit of the oscilator, and I remember Phil saying the new crystals did not like having that much voltage across them. Best to find one of the old large can style ones that can take the voltage, trick is finding one that's still good.

The CTC-9 I recently sold had a good crystal in it, the CTC-7 had to be replaced before it did anything, and the one in the CTC-4 still seems to be good. So it's hit and miss, I guess.

This may have been me. I was working on an RCA set and stuck a used crystal from a modern solid state set and it failed after a week. You can use the small crystal in this set. I have two of those style Zeniths running with new crystals.

Someone explained why the crystals go bad once in one of these threads. They called it 'silver migration', Where the crystal gets contaminated by the metals in the leads or something like that. A whisker type disease.

Its not just tv crystals. I used to collect EF Johnson CB radios and today the whole collection is a pile of dead radios. All 20 crystals in every radio is way off frequency and their hardly worth fixing. It would cost several hundred dollar to renew each radio with a set of custom made crystals.

[ctc17]

To be more specific they are 3.579 mhz crystals. For a rough idea....

http://shop.ebay.com/i.html?_nkw=3.5....c0.m270.l1313

[compucat]

Originally Posted by Tubejunke

Thanks! What model/year do you have? I NEVER would have thought that this set would be any type of attention getter; especially with the metal cabinet, which I have been told makes it MORE special. Have you checked any tubes yet? Since your set is restored, I tend to think of tubes going as opposed to caps, but one never knows for sure I guess. The tubes I replaced to get my set working were not absolutely bad on a tester, but more marginal or weak. Maybe color sets like fresher tubes! LOL!

My set is a 1965 model with the 25MC33 chassis. It has the UHF tuner as an outer knob around the pull-on volume knob. I have tried replacing tubes in mine to fix the vertical to no avail. I suspect a resistor or cap has gone bad. I am going to replace the electrolytics and troubleshoot the vertical problem. It has nothing else wrong with it. Of course I will redo the convergence and setup as I am never completely satisfied with it. I am rather fussy when it comes to my vintage electronics. I hope you get that color problem sorted out. That set is well worth the effort.

[Tubejunke]

Originally Posted by ctc17

To be more specific they are 3.579 mhz crystals. For a rough idea..

OK! I remember those in the Bearcat scanners when I was a kid! I wonder if they can be tested with a DVOM. I tried to download a PDF datasheet, but I guess my Adobe Reader is screwed up because it would not "decrypt" the data. There is a business in my county that once had all of this stuff and anything else you needed for radio and television. The sales floor was once like an old Radio Shack, only with test equipment, parts, and high end stereo/hi-fi equipment instead of toys. These days I must luck out and find the original owner at the shop to even talk about an electronics need. He will still order some things and last time I was there (2-3 years ago) he still had a room full of tubes that never got sold. He may just have a few crystals around! I have to find the owner because the kids at the counter only know about the BOOM BOOM car stereo equipment that the store now specializes in.

If I thought that I could make it worth the investment, I could probably buy the inventory of tubes at a good price. The last investment I made was in NOS yokes and flys which I still have quite a few of. The popular #s like FLY 1 went pretty quick, then it died....

[old_coot88]

Hey Tubejunke

Can you post a schematic of the color section? I'm betting that the problem is something other than the crystal, based on your statement that the color was strong and in sync prior to the sudden drop-out.
Bill(oc)

[Tubejunke]

Originally Posted by old_coot88

Can you post a schematic of the color section? I'm betting that the problem is something other than the crystal, based on your statement that the color was strong and in sync prior to the sudden drop-out.
Bill(oc)

I don't have a way to scan a schematic, but later today I might be able to post or send you a PDF to look at. Again, from the get go the color took maybe five minutes to come in, but when it came in it was fine. I thought for sure that it was just a weak tube that was taking longer than others to achieve enough emission to do its job. Each time I powered the set it seemed to take longer and longer, till no color at all. I have a lot of studying to do for electronics tests this coming week, but I hope to at least have time to give the color killer potentiometer a good cleaning in the next day or two. I doubt that is the actual problem, but I know that it needs cleaning as it was a bit jumpy when I tweaked it the other night. Also, I need to give the underside of the chassis a better visual inspection and maybe check out some resistors. I already found the horizontal "efficiency" coil that seems to have a broken backbone (plastic), but it doesn't seem to be causing any problems. However, it might be why the horizontal hold control is off center. For now I want to focus only on color issues.

[ctc17]

If its that toug to find one pm me your address and ill send you one. - keep several stock because they are always bad. Sometime I forget I live in LA the land of everything instantly

[old_coot88]

Originally Posted by Tubejunke

...Again, from the get go the color took maybe five minutes to come in, but when it came in it was fine.

Uh-oh, my bad. I missed that statement, but found it upon re-reading the thread.
Sure sounds like like the 3.58 oscillator tube was slow warming up and finally not starting at all. Do you have a known good sub for it?

..I thought for sure that it was just a weak tube that was taking longer than others to achieve enough emission to do its job. Each time I powered the set it seemed to take longer and longer, till no color at all.

Here's assuming the problem is a weak 3.58 oscillator; with the color killer full 'on', you'd see barberpoling gradually straightening up until the color finally locks in.
(An analogous situation would occur with a weak horiz. oscillator. A good working test for the H. oscillator is to turn the set off for ten seconds or so, and then back on. If it takes a while to lock back in, the tube is borderline weak even though it may show good on a tester.)

Speaking of horiz. stuff, the 'efficiency' coil does not affect horiz. sync. But if mistuned, will cause high HOT current. It needs to be tuned for the 'dip' of minimum current.
Bill(oc)

[Tubejunke]

Originally Posted by old_coot88

Sure sounds like like the 3.58 oscillator tube was slow warming up and finally not starting at all. Do you have a known good sub for it?

By mentioning the 3.58 oscillator tube, do you mean the "Chroma Reference Oscillator? That is the only color related tube that I see that is called an oscillator. The rest seem to be amplifiers and demodulators. I will have to look for a sub, but I don't have a "known good". I will get back to the issue with the horizontal efficiency coil with what seems to be a broken backbone or housing. In short, I would think that it should be rigid, but I can grab the coiled end and it wobbles around separating the windings a bit.

[Phil Nelson]

Originally Posted by miniman82

I remember Phil saying the new crystals did not like having that much voltage across them. Best to find one of the old large can style ones that can take the voltage

Before I found the right type of crystal for my CT-100, I tried one that I salvaged from the carcass of a junky 1980s TV. It made a sizzling sound and died. I don't know what will work in this set.

Speaking of crystals, my CTC-7 has a funny one. The manuals show the can type, but this looks like a chubby glass mini tube with a saucer inside. Perhaps a replacement. New to me, anyhow.

Phil Nelson