color stripes on screen (slyvania roundy)
 

well, checked all tubes, surprisingly only the high voltage tube was barely weak, low end of green, so i replaced it.

Colors are all messed up, when i dial in the fine tuning, i get what appears to color stripes on top of a back and white picture.

It also has a crt booster plugged into it.


any ideas, please tell me recapping this will fix this

Color stripes on a b&w picture... check the color oscillator tube... 6GH8. It may be tired (they usually are). It's always good to have spare 6GH8 tubes on hand for color sets.

Weak/leaky caps could cause this as well... so yes, a recap might correct it.

The oscillator crystal under the chassis could be bad (cheap and easy to replace).

Even after replacing the above parts, you may still need to adjust the fine tuner to get a color lock.

Charlie, can u post a tube diagram layout, i followed the tubes that were in there, as most of the paper was ripped off the hv tower

I don't trust what was installed, maybe somebody made a mistake previously.


I seem to recall 2 6gh8, they both tested ok


also, what chassis is this?

I am not home... I am on board ship... I have no access to a tube layout.

Maybe we can try this from memory (I smell something burning already).

I'm just going to assume your chassis is an RCA clone...similar to a CTC-15. With that being said, the color board is the one in the middle... at the rear of the set. This board has two rows of tubes... the forward row has 4 tubes, and the aft row has five. The 6GH8 you're looking for would be in the row of five... tube number 3... in the middle.

I've seen some 6GH8's that did not provide a lock... or was slow to do so... and still tested good in the tester. In my CTC15, I plugged in several different tubes before I got one that gave me a good, fast color lock.

my roundie combo sitting right next to it is a ctc-15, so that tip helped a lot.

I replaced the two 6gh8's with new ge, colors are stronger but still in a striping fashion.

Thanks for the tip on the crystal, looks like it's time to start recapping.

Try this. Ground the grid of the 3.58 tube. Adjust the osc. transformer for this combination: minimum number of color bars AND to where they stop floating.
Use a color generator if possible.

I'm ignorant of this, and u just went 40,000 feet right over my head.

I still say it's that .01 @ 1 kV white Elemenco on the board. That is exactly what happens when it goes BANG. Happened on my CTC-36. Replace the cap, and watch TV :)

Thanks for the great advice, but slight correction, .001 and 2000 freaking volts. Just radios has that in 6000 volts. for like $5 each.

Time to pull a chassis and start making a list.

Well, whatever it is, betcha that's the bad one. The one on my 36 was 1 kV iirc.....

Color is way off frequency, the more bars you can see the more off frequency it is......

If you don't have a tube chart (layout) look on top, or bottom of chassis for a color crystal, its aluminum, about 3/8 thick, and maybe 1 1/8" long, curved on the sides, about 1" tall, flat on top, and most likely has 3.58mhz or just 3.589 stamped in the top. The set will have only 1. Your color circuit is right near this item. This is your color oscillator crystal.

Your color osc. tube will be near it, the cap former Captain Picard is talking about should be near this item. 6GH8A's have short lives, you should keep a few NOS spares, you can switch out from that set to another to try, or with another in that set if you don't have another, you might see a difference if its weak or bad.

For this problem, look to color oscillator, or color afc, circuit, there is a rectangle 3 wire afc diode in that part of the color circuit. Its usually black plastic - almost same size as the color crystal.

PS both the crystal, and the 3 wire diode often are not the problem.

Actually now that I think about it more.... I think the 3 wire diode is the Horiz afc, and not color afc, so forget I said that... getting old....

Also, those caps with the thousands of volts are high tolerance caps, and high voltage rating because it is a critical value not to drift in value, don't worry there is not that much voltage there, its to keep the value stable.

a 1600 volt cap would sub ? just a guess .

mike

oy vey

tweek the freaking osc coil 1/4 turn tall right next to the 6GH8 go 1/4 one way if more bars go the other way. Don't go crazy if it does not help its prob the crystal.

oh yea and use the correct tool so you don't break the core.

This is what reeferman was telling you a while ago, just without grounding the grid 1st.

when you say HV tube what tube are you talking about? IF you mean the HV rectifier, then a tube tester is not much good unless its really bad, those operate at 25kv plate voltage, way above a tube tester. Besides most tube testers test them with a simple pass fail measurement should be marked on the testerd "diode" most likely at the bottom. Besides all the above color lock has nothing to do with HV anyway.

Have you checked for bad solder joints?
Crystals seldom go bad.
Only recap as last resort.
The tool has a 1/16" hexagonal on the end and made of plastic. Commonly referred to as a diddle stick. Should be available at Radio Shack.

Assuming you have a CTC-15 clone the attached drawings should apply. In drawing 1 you are concerned with tube V703 and reactance coil L702 (which has only 1 ferrite core (slug) to adjust. Drawing 2 is the schematic. Short pin 2 of V703 to chassis ground. Don't worry about the "B" in the V703B. Adjust coil L702 for the minimum number of color stripes (bars) and at the same time have the color stripes stop moving (floating). Go ahead and play with it. You'll see that moving the coil one way will increase the number of color stripes on the screen and the other way decrease the number of stripes. Go for the minimum number.

Before starting I recommend setting the color killer control. Go to an unused channel and adjust the control all the way to the end that gives you color snow. That way your set might not try to cut back or even kill the color signal.
After adjusting the reactance coil L702, adjust the color killer control by turning to an unused channel, adjust the control to where you have color snow, then back off until snow disappears. A simple adjustment people overlook.

and this correct tool is called what?

squirrel boy, u got a web page where i can buy that crystal? Is it model specific, i'm hearing my chassis is a ctc-15 clone

is there one on ebay?

Don't be sorry, I'm just starting out and appreciate all the help i can get.



Right now, I'm going to replace this crystal and recap the set.

in my limited knowledge, 49 yo old caps seem highly suspect. Besides after the debacle with the magnavox, as least i know which end is which on an electrolytic, lol.

Don't replace the crystal......

The tools to adjust coils are made of plastic, you can get them on ebay, you use to be able to get them at radio shack for less than $5.

http://www.ebay.com/itm/GC-Radio-TV-...item19dff14f8f

Ooy vey indeed. Assuming the set is a '15 clone, the "color oscillator" or "color lock" adjustment is called the 'reactance' coil. It sits adjacent to the color osc. tube and is not in a shield can. It's tall and narrow, having a single winding and single slug. Can't miss it.

The tool is called an alignment tool or 'diddle stick'. It's non-conductive, made of either nylon or plastic. Radio shack used to sell them. If they don't, somebody here must know a source.

(edit) OOPs. Didn't see the above post. Do try the reactance adjustment before messing with the xtal.

so your saying try to adjust this thing, and then if that doesn't work then recap?

ok i bought it thanks.

Crystals hold a very fixed, and very steady frequency. If the number of color bars increases or decreases wildly, then it may be the crystal. It may be the crystal if it is very far off frequency and you can't get it back on.... Lets put the crystal aside for now. They are not set specific, so one temporarily swiped from another set will be fine. No polarity either.

While I have not worked on a ctc 15, It sounds like "old coot" has, follow his advice and adjust that coil he identified, if you have the plastic tool. Its plastic so its material does not effect the coil. If it were metal, like the iron core you will be adjusting, the tool itself would change the value of the coil as you put the tool inside the coil. The coil will have a center shape like an allen wrench.

Adjusting that coil will either increase the number of color bars, or decrease the number of bars.... You want to reduce them unitll the color locks, similar to horizontal hold. If you can not achieve a stable lock with adjustment, then you have a bad component, resistor, tube, cap.

One thing you can do is to run the set, and spray a little freeze spray on some components around the crystal, to see if you can find a sensitive part, it may be bad. Long shot, and don't waste the entire can. Just a drop or two on components you know are in the color circuit. Don't spray tubes. Freeze spray is a good tool to have, also called component cooler, also ust to be available at radio shack. Maybe also available on ebay.

Be careful when re-capping in the color area, those caps are tight tolerance. Better to try and find the bad parts.

Also see if you can get a schematic from someone here, or ebay, and begin to learn about these circuits so you have some idea about recognizing the parts, and parts of each circuit that depend on the previous circuit for the set to function properly. Sam's have lots of cool stuff in them, even if they are not perfect.

Have a good night....

See my revised post #16 with drawings

Hey thanks i appreciate it. I just ordered the alignment tools on ebay and the sams. We''' see if an adjustment will fix it.

Thanks to reeferman for posting schematics, I would turn coil 703, which is the 3.58 osc. the other coil looks to be tint, or phase. If the frequency is not right, adjusting the phase will do no good. Think of adjusting the frequency as the course adjustment here, and phase, as a fine tuning to get the color right, once the osc. is locked in....

If you short pin 2 of the osc. tube I would imagine the bars would go away...... is this not true reeferman?? Turning off the color osc?

Well whatever you do, don't turn both coils without returning them to their starting point. If you turn one 2 turns to the right, remember it and return it to its starting point. You don't want to throw the set out of alignment for what may turn out to be a bad cap, or out of range resistor, or open resistor..... Check the voltages that are on the schematic while you are there....... First.

L702 is the correct coil to adj. it the one that is a coil ouside the can next to the 6GH8. turn it 1/4 turn one way see if you more or less bars if more go back turn 1/4 the other way. It should not need a lot of adjustment.

that reddish thing?

http://paintforcars.com/Merchant2/im...to07292226.jpg

yes the reddish coil

A few things with the usual IIRC's & IMHO's.
Only remember 2 kinds of the big xtals one had a third
ground wire soldered to the case. All 2 legged ones were
the same, even sold under ECG. They did go bad more often
than components.

If you have sets infested with 6GH8's you need to keep some
NOS BRAND NAME ( no rat shack) ones around. They are also very touchy
as to the circuit they are in. They can work fine as a sync
separator but not work for color osc as an example. If you
shuffle them around usually you will change symptoms.
They were so bad that we bought them by the gross 2-3
times a year for 29 cents.
I could tell you more stories abt 5 & 6GH8's.....

Most coils in TV's never even need tweaking. If you do it
put a flag on the tool. This way you can put it back where it
was. Count & write down & keep the note. I used to note it
on the slip " L703 3/4 CCW" if it came back again I could go
back & find the problem.

For your problem your freq is way off so start with 6GH8,
several if used even from a known working set. Next the
xtal. Then easy voltage & resistance checks. After that
caps one at a time ! But thats me...........

73 Zeno:smoke:

I saw a comment on your youtube channel in regards to your sylvania. Some guy wrote "i live in NY and never see these kinds of sets for sale."

oh, the irony.

For any color sync issue, i would also routinely sub the burst amp with a known good one (6EW6, IIRC).

For the heck of it, check L702 (reactance coil) for continuity. Back in the day, i do remember a few instances of that coil being open.
The chroma circuitry here is common to CTC-15, '16, '17, '25 and their clones.

The color stripes will stay with the grid grounded.

Do not adjust T703 at this time.
If you get the color to sync but can't get a good flesh tone at the center of the tint/hue control we can address that issue then.

not sure what may have done it, i pulled the power booster, let the set for the first time for more than an hour, had it running for almost three hours, then played with the tone and color controls.

She finally locked color. Clearly she could use a recap still, but for the time being i'm calling this done.

Now to get on the rca roundie combo, and my 300 lb sylvania combo monster.

Power booster?? Are you talking about the CRT brightener? Removing the brightener will not help or hurt your color lock issue. Sounds like after a few hours of running, the heat buildup in there changed the value of something... cap, resistor, coil... maybe even caused a ground connection to make better contact.

Tomorrow, you may have to start all over again... take a few hours to lock.

At least now you know it WILL lock... it's just a matter of finding the part causing the problem. I think it's a cap or resistor changing value.

The 3.58 oscillator tube (V703) could still be borderline weak even if you've changed it. There's a 'quick and dirty' way of determining whether the tube is weak or not..
With the set fully warmed up and the color in-lock, turn the set off for about 7 seconds and then back on. Is the color still in sync? If so, the tube is good. Or is it back to stripes, taking a while to re-acquire lock? If the latter, the tube is borderline.

(This method can also reveal a borderline hor. osc tube, osc/mixer tube in the tuner, etc.)

have swapped out several tubes in the color circuit no major difference.

Good.
Make the adjustment anyway. You won't screw anything up.
Are you getting flesh tone at mid-range on tint control? (on a live broadcast)
Phil

Another thing that can happen is with a set sitting unused and/or in an unconditioned place for a long time, moisture can creep into coils, etc. and throw off proper operation. Heat from operation can dry that out. Also you can put a light bulb inside the cabinet to maintain gentle heat for a few days to speed the process. Be sure to clean all tube pins and sockets, too, as contact can be "iffy."