20 inch GE CTC166CS chassis red smearing but strong CRT

[MRX37]

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

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

[MRX37]

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.

[old_tv_nut]

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?

[JohnCT]

Originally Posted by MRX37

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?

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

[zeno]

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

73 Zeno
LFOD !

[MRX37]

Originally Posted by JohnCT

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

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.

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.

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

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.

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

[MRX37]

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!


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:


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.

[zeno]

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

73 zeno
LFOD !

[MRX37]

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.

[JohnCT]

Originally Posted by MRX37

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?

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

[MRX37]

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.

[sampson159]

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

[MRX37]

Originally Posted by sampson159

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.

[old_tv_nut]

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

[zeno]

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
LFOD !