20 inch GE CTC166CS chassis chroma smear but strong CRT
 

I found what is basically an RCA Colortrak TV, only it has a GE badge on it. It was made in February 1992, and is a CTC 166 CS chassis. So basically an early Thomson built rebadged RCA set.

I am pretty sure this set is a low hour set. I do not have a CRT tester, but the CRT produces a good picture even with the drive and bias controls set to absolute minimum. The inside of the set was relatively clean, not very much dust on the HV anode lead, and with the brightness and contrast set at their midpoints I have a nice bright image with the bias controls turned all the way down, and the drive controls turned up maybe 1/8th of a turn if that. Other than that I have just made slight adjustments to the G2 and focus controls.


So here is the problem: Red or red/orange colors are a little bit smeared. It's not much smearing, but it is noticeable. Color level makes it worse and I know its not my video source because if I turn up the CRT drive controls, the onscreen menus start to smear.

I have seen this before on CTC 158 chassis sets (RCA Colortrak 2000) and I don't think the issue is CRT related. I'm wondering if something on the chassis has gone out of spec.

Does this set have separate G2 and bias controls?

Yes.

By the way, picture of the smearing I am dealing with:

https://i.imgur.com/FDSt96c.png

It's not much but it is enough to bother me.

Hard to tell from that picture - does it look ragged and changing like a torn fabric and comes or goes abruptly as the color is turned up, or stationary, intensity varies smoothly with color control and gradually fades out to the right?

If ragged, it's a bias/G2 problem, possibly fix by going through proper G2 and bias set-up procedure. I suspect this isn't it, because the white rectangle isn't showing it. Edit: try turning brightness and contrast to max to see if it appears on the white rectangle.

If stationary and gradually fades, it's a chroma smear. Maybe can be improved a bit by fine tuning.

It looks to me like the blue part is smeared too, which would also say a chroma smear.

I'm leaning towards Chroma smear. It's not ragged at all. No, the smearing is smooth, changes with color level.

Brightness and contrast at max do not affect the white rectangle.

I should also note that I am running an S-Video signal, so the tuner is not involved at all.

I realized I am being a little stupid about this. I have a good camera and a YouTube account so why don't I just show what's going on rather than try and describe it? Just need to find some commercials so as not to trigger the Copyright fascists...

https://youtu.be/NBcuLOPp1og

Look at 0:32.

The orange bar is dark on the left edge and smears to the right on the right edge.

I'd say this is a combination of the normal low bandwidth of chroma plus a mismatch of chroma and luma delay. The delay mismatch probably arises in the cable box (or whatever your source is), which doesn't have a luma delay to match the chroma bandwidth, and not in the TV.

At 0:40, it's also obvious in the logo in the video just above the menu.

I could believe that, but it shows up in the onscreen menus (not to the same degree unless I turn the drive controls up)

I mean if that's just normal for this chassis I can live with it, but I'll probably never find another one of these in this good of shape, so I just want to make sure its working at its best to have a good reminder of what a properly calibrated CRT looks like.

There is another thing that is not a problem right now, but could be a problem in the future. I need to add some context here.

I am more familiar with the CTC 158 chassis. You unplug one of those, plug it back in and turn it on, and it starts autoprogramming because it lost the channel information. This CTC 166 remembers its channel info. Great!

It also has an on screen clock that displays accurate time. Great!

Uh, wait... that means this TV has a real time clock, which as far as I know should be powered by a battery...

...A 28 year old battery...

Now I have looked at the chassis. I have not had it out of the set, but I have looked at it and seen nothing like a battery. If there is one in this set, maybe I should know about it before it decides to leak and destroy traces on the circuit board.

The smear looks like it may be normal or just a little off. That means
it will be tough to find. If you take a pix of the chassis something
may come to mind.
The clock probably uses a big cap to hold time. Batteries can surprise
you. I had an old Zenith R472 series clock radio sitting for years. My
sis needed one so I cleaned it up & test ran it a few days. It sat a day or two
unplugged & when it came up the clock was right ! Not bad for a
40 yr old battery:banana:

73 Zeno:smoke:
LFOD !

Some batteries look sort of like capacitor or were primative super capacitors. Oftentimes they will have unusually high capacitance like 100000uF or xF listed... having a schematic or service manual makes IDing parts like that less of a guessing game.

This thread remained me that I have an RCA console tv from 1989 that needs to be fixed. The tv no longer powers up. I have not done any work on it yet. The crt in mine is little weak but still makes a very good picture when it was working

I don't see it in the COLOR and BRIGHTNESS menus you popped up in the video. The set's on-screen menus(not those from your cable box) are generated by RGB signals, I believe, and can only have small color fringing due to misconvergence, nothing due to chroma smear/delay.

Then what do you make of this?

https://i.imgur.com/nEmmgKV.png

OK - that's obviously visible. At this point, I'm out of guesses. A schematic might help.

I wish I had one. I do have the layout they provided:

https://i.imgur.com/Mw3jk8e.jpg

I have been looking around, and the only source I see for service info is SAMS, and they want $22.00 for a copy.

Mmm. Do I bite the bullet and pay $22.00 for service information on a TV that I don't really need, but has sentimental value to me?

Well let me answer that question with a question: Is this chroma smearing a legitimate issue or is it just a limitation of the chassis design?

My gut tells me that since the TV's own menu is affected, it's probably aging capacitors. I'm thinking of that 33uf by the flyback, but do I want to pull the chassis and start shotgunning capacitors? Or do I want to get the service info and attempt to actually diagnose the set?

I do believe that the CRT is pretty strong. I turned the G2 control to its minimum and could still see a decent picture, yet the chroma smear was still present.

You need to find someone familiar with the Thomson chassis to tell you if they were normally like this.

To help answer if this was expected, it might help to know where it was built and by whom. What does the label say about country of manufacture?

No, the 166 was a fine performer with no known vices. Also, incredibly reliable.

I remember having a problem like that with the jungle chip in several brands (I think Toshiba and Sanyo made most of the jungle ICs for the industry). If it uses the same one as the 169, I might have one. I scrapped out most of my analog chassis some years ago, but I have friends who might have an original jungle if you post the number.

As far as the cap off the flyback, if that was giving you problems, you'd see a brightness shift from one side of the screen towards the other. Put the picture to zero and lower the brightness in a dark room. If the picture is evenly lit, the cap for the kine source is prob good. The easiest and best way is to scope the 200V right at the CRT socket.

If the smear is on just one color, it could even be a problem at the CRT socket board. A cranky kine drive transistor could do this or a shorted inductor on that one color. The inductor will read fine resistance-wise but a shorted turn will cause a smear.

EDIT: if it affects one color, you can swap the red/gree/blue signal input leads to the CRT socket and see what happens. The color will be all wrong but we're interested in the smear. If the color smear doesn't change, the problem is on the CRT socket board or CRT. If the smear shifts color, it's on the main chassis - perhaps the jungle IC or one of the buffer transistors between the jungle and CRT socket board.

John

First off I have the REAL Sams for the RCA version. Not a PDF or Xerox.
If interested PM me for price.

Looking at things in the chroma shows no adjustments and just a few
'lytics. I dont think its normal. Its bad enough that I would have seen in
the day but probably not the customer. Had this come in FOR that
problem we probably would call RCA TA first and if no answer give it
back & tell them to take it to RCA service. Let them loose there shirt on it !
But who knows ? You might take some voltages & find something off and obvious:D

73 Zeno:smoke:
LFOD !

That's what I figured. I know the quality took a nosedive after Thomson acquired RCA and GE, but the 1991-1992 sets were still well made. That's why I saved this set.

The smearing is rather slight. I would think if the IC failed it would be a hard fail with significant changes to the picture.


It affects all 3 colors. I thought it was just red at first but its all 3 colors.

Since I had some time today, I decided to pull the chassis out of the set. The idea was to use my LCR component tester to test some capacitors, if anything just for my own curiosity, see how well the caps in the high voltage areas have held up.


Oh hello sir! You look bulged!
https://i.imgur.com/6tMssg8.jpg

That cap is a 4.7 uf @ 50 volt, and it's right by the Horizontal Output Transistor.

No... Did I really get this lucky? Is it that simple? Well lets pull it out and test it...

Annnd yyyyeeeaaaahhhh it's reading 39 pf on my tester. I'm gonna say that cap is bad.

Now this is interesting. I happen to have that exact same cap, and I mean the exact same:
https://i.imgur.com/IIhvVQd.jpg

I pulled the cap on the left out of a CTC 158 chassis, and it tests good. So lets pop it in and see what we get?


No change. Picture looks the same. Eh I didn't think it would be that easy anyway. However it would be nice to know what that capacitor does, because that was definitely a problem, if not the problem I'm chasing.

The cap probably C4306. It filters the primary of the hoz drive transformer.
Find C4701 680mfd probably near the HV transformer. If it opens
it will cook C4306.

BTW will send your pkg tomorrow:thmbsp:

73 zeno:smoke:
LFOD !

Do you mean C 701? Cos that's a 680@ 50 volts. It checks fine.

And welp I have another problem now, one of my own making. I don't think I had the CRT anode lead reconnected properly. Turned TV on, heard a small pop. The TV now turns on and off. Disconnected and reconnected the anode cap and made sure it is seated properly. The TV still turns on and off by itself.

Welp no one to blame there but myself. What did I screw up?

Edit: Scratch all that. I forgot to solder one leg on a capacitor.

Do you mean that when you apply AC, it power cycles until unplugged?

I hope you didn't smote the micro. IIRC, that micro has the software inside, and it came with instructions for configuring it to the exact chassis version (used in several). You get one shot to configure it correctly using a series of key strokes.

Unfortunately, I dumped all my analogue specific stuff years ago, although recently I stumbled across a ton of original Philips ICs from the 80s and 90s if anyone is crazy enough to have one of those!

If you don't have a schematic, I probably still do and if I can't, one of my buddies was a sams subscriber and he has pretty much everything.

John

Fixed it.

I had forgotten to solder one leg on a capacitor. So, just simple dumb oversight on my part. TV's working again.

Also have a SAMS coming my way so that's taken care of.

we called this,"firing up".can set controls lower to correct.could be a weak crt but it looks ok.set your controls a little lower to see if it helps.we have some low grade crts that had this when they were new.admiral,rca,etc where very common.only very low level sets

Smearing shows up regardless of Brightness and Contrast settings. Only the Color setting affects it.

I don't have a CRT tester, however the CRT still produces a watchable image even with the G2, kine bias, and drive controls set to their minimum. I very highly doubt a weak CRT would be that bright.

Unless I have an epiphany I'm just going to wait for the SAMS to show up in the mail, then start looking at voltages.

Do you have a different source to try, like a DVD or BluRay?

Another thought.... IIRC the jungle IC in these was a Toshiba
TA8680. They were VERY high failure mostly for bad audio & AFT
problems. They were used in tons of brands & kept steaks on the
table for a few yrs. I did so many in Toshibas that I could do a complete
repair in abt 10 mn. The paperwork took longer !
Anyhows since I dont have the manual anymore cross the jungle IC to NTE
see if it comes out to NTE7010. If so its the same IC. The cross will
also pin out the IC so you can see what each pin is for.

BTW This IC shows some of the BS in parts prices. I could get them from
Toshiba for about $8. The same thing from Sharp parts was abt $25.

BTW #2 If you cut one open a jungle IC you will see its not an IC but a bunch of IC's in one pkg. Often each one has a separate VCC & GND.
Something to keep in mind.

73 Zeno:smoke:
LFOD !

Yep. Got another converter box, a DVD player, another DVD player with S-video, and so I can use this TV with a more modern source, I have an HDMI to S-video converter coming in the mail.


I doubt it's the jungle IC because the customer controls work, and the smearing is slight. Frankly if it's the jungle IC then I'll just leave it alone. I've changed one of those IC's before. It is not fun. It is tedious, and I have lifted up solder traces before.

Not exactly germane, but C4502 is a problem child as well. Might be well off replacing it. See the various symptom/cures in the PDF. The RCA listing for the CTC166 is 3 pages. Hope it helps.

Cheers,

Oooh. Now we're getting somewhere! I'm still waiting on the SAMS but will pull C4502 when I find where it is.

So I received my HDMI to S-video converter, which is sweet because now I can hook this old TV to modern video sources, and I get to show off why I like these older Colortrak 2000 based sets:

https://i.imgur.com/FauRhEt.jpg

The camera does not do it justice. Those are small fonts, readable on the TV screen, at 800x600 resolution. However you can see how smeared the icons are.

Now I did notice using a DVD player that it's not just chroma:

https://i.imgur.com/pkxoMbi.jpg

The smearing happens with pure luma. I can see it better than the camera can.


EDIT: I decided to snap pics of the screen at different color levels:
https://i.imgur.com/gXu9Y9E.jpg

On the left, color level all the way down, and you can see just how freaking sharp the picture is. I mean for a standard def analog TV running over S-Video, that is freaking sharp!
In the middle: Color at midpoint: Still sharp but you can see how smeared the image has become.
On the right: Color at max level. The smearing is not any worse (at least it has not extended farther which definitely tells me it's not color bleed caused by a weak CRT) but the icons have lost their definition.

I think I need another way to go about this.

I have a copy of the SAMS now, and while it has given me information, it hasn't given me the info I need.


So lets try something else: What are all the things that could cause the colors to smear?

Bad CRT? I doubt it because it's plenty bright and there's a lot of headroom on the drive and bias controls.

Bad U1001 IC? I doubt that because otherwise the TV works fine. Tint works fine. Color level works fine. all menus work fine.

Bad capacitors? I have been spot checking them since I did find one that was bad. However that is the only one I have found. All the capacitors in the horizontal and vertical circuits check out. The caps around u1001 check out.

Bad component on the CRT neck board? I have seen color smearing caused by bad electrolytic capacitors on the CRT neck board before. I found one of the old CRT based iMac's that had that issue. However this RCA has no electrolytic capacitors on the CRT neck board. It does have carbon resistors, but the one I spot checked reads fine.


Don't have a CRT tester so can't test it to see if there's an issue with cutoff or maybe a short that's bleeding off the video information?

There's a thought! Yes it is almost like the color information is being bled off.

Here is what I am getting at: https://youtu.be/hC0yyphcahw

This is a video on a TV with a shorted CRT. shango066 rigged up a way to isolate the short so the TV would work, and you can see near the end of the video, when the CRT shorts it gets all smeared because the video information is bleeding off into the isolation transformer.


I don't think my CRT is shorted. If it was I doubt the TV would even turn on. However I do wonder if the reason the colors are smeared is because the color information is not fully getting through, or it's being bled off by a bad component?

Do you see the smear on EVERY source you have? Or, is one (the DVD?) better?

You could have more than one thing going on, so let's try to clarify:

1) What is the source of the menus in post #14? Is it an internal menu from the TV, or from an external device? If internal, this may be a separate problem with the menu video injection (separate from the chroma delay you see on external sources).

2)The external sources you have shown so far all seem to have the chroma delayed compared to the luma. Maybe a luma delay line problem, but I would think if it was a bad delay line, the luma frequency response/transient response would be messed up.
Some external sources may not have the luma/chroma timing adjusted to NTSC broiadcast specs, so if the luma delay is a bit short on this model of TV, it will be made worse. [NOTE: NTSC broadcast transmitter specs include an envelope delay filter to delay the luma with respect to the chroma sidebands. This was specified to match the flat sharp cutoff IF amplifiers of the original receivers. Later, manufacturers found it better to use a "haystack" IF response, which did not match the transmitter filter. This was compensated by using a slightly longer luma delay line in the receiver. This chassis may simply use a slightly short luma delay line, the effect of which is made worse by the lack of a lack of envelope delay in common sources. Unfortunately, there is no analog station on the air that you could use to check.]

3) Have you tried to see if it changes significantly with fine tuning? [Thinking IF alignment or chroma alignment could be part of the issue.]

Post 14 is the TV's own menu.

This TV is from 1992. It has no fine tuning that I am aware of. Also I am running it off of S-Video which should not involve the tuner.

The luma delay line is worth exploring, but where would I find that? Luma and Chroma are controlled by a big IC.

This has an electronic tuner rather than mechanical, right? (So no fine tuning, just enter the channel number).

Can you check the schematic or post portions for the following:

IF: is it a surface wave filter (no or very few adjustable coils)?

Delay Line: should be a tubular coil a few inches long and a half inch or so in diameter, with the schematic symbol shown.

These are gonna be pretty big images, but I wanted to make sure everything was easy to read. This is the schematic for the chassis:

https://i.imgur.com/gI8b7nb.jpg
https://i.imgur.com/FDNLSs5.jpg

I've been following it best I can and have tried tweaking the 3 coils near the IC area, to no effect.