CT169 board :)

Nothing holds the 169 in there only sticky dirt on the track..

There's probably dirt holding it back.

The cause is usually from bad capacitors in the vertical deflection circuit. With age, they can become thermo sensitive. You can find these with a heat gun, cooling spray, and an ESR meter.

Jerry G. ======

You've taken the three 1/4" screws off the back panel that holds it to the frame and flexed the plastic holders on each side of the back panel outwards to release the chassis? That's all there is. Solder the bad connections after scraping any glue off the top of the chassis which is easier said than done, and you'll have a nice set.

Hi Kip...

Thanks! Naturally you're right.

Perhaps this is the first time this one's been out... sprayed it with a little wd-40 just to wet it and it slowly but surely jerked out... inch by inch. Tough part is keeping it going straight.

Anyway, appears to be old dry sticky left over flux on the edge of the board.. gonna gently sand it off in case it needs to come out again.

Thanks again, and take care.

Ken

Hi Jerry...

Thanks very much, appreciate it. Seemed to be extra dried up flux on the edges of the board.

Hoping that just a reflow will do, given that I can turn it on and off with just a bit of a tap on the case, but if not I'll be sure looking at the caps :)

Oh - one more thing... I retired before these things came out... wouldn't mind touching it up while I'm at it. Is there no longer a service switch (or jumper) to completely collapse vertical?

Thanks again, and take care.

Ken

I'm a pro, and don't just mean I get paid. That back panel on the CTC169 is to be removed for service. Others don't do this. There is a metal frame on the board and between that and other things you can keep the pressure even when you pull. This is impossible when the plastic is in place.

Anything stickying up the wicket makes it all worse. Once I get my hands in the right place and pull, if it doesn't come I cut the rails.

RCA is great with this mounting, you spill one drop of Coke into it and it's wrecked. I worked on a CTC140 one time that had the foils peeled off in those tracks.

I always take the plastic shield off a CTC or PTK169 before anything. Now realize that I can troubleshoot any of these chassis' with a dead set symptom in about 2 minutes after that, if even that long. I have literally worked on hundreds of them. I am telling you, remove the plastic backshield from the chassis. Failure to do so can result in overstressing the SMD components at the very least. Then you get intermittents that can be very hard to solve.

On your last point, none of us use, well to my knowledge, service switches, even if they exist. You use the G2 and bias to get color balance with the contrast all the way down and the brightness at factory default. The color is all the way down, you get a balance down there, and make SURE you don't have retrace lines, then you crank the contrast and the drives (on that chassis it is red/blue differential and green), are what balances the high brightness areas. Some find it a bit difficult to work with this setup, but not all.

There is a master setup procedure for all sets. I'll tell you but not now. I must go.

The old bed/worktomorrow cross.

JURB

Ken, your instincts are correct, it's not caps. Occasionally, you'll find the vertical yoke coupling cap (high value) vented, but it won't intermitt. I've had several 169s that had bad connections causing vertical loss.

I think the 169 has a software service switch. Try holding down the menu while plugging the TV in, or holding the menu when turning it on. Like Jeff says, the best gray scale tracking is usually achieved without a service switch. Older CRTS don't track perfectly, so setting up the base screens is best done with the contrast to zero, and the picture dim. This will give you a different setting than if you did the same using a service switch, which kills *all* video. You'll then find that when you adjust the drives for best whites, it's sometimes advantageous to fudge the screens again, then back to the drives again.

John

That's one strange thing I noticed in my 6 or so years in this business...the most typical, multi-manufacturer failure of all, the cap causes vertical IC to fail...was not typical at all of most of the larger TCE sets.

Tom

Tom, you're correct. Vertical failures is extremely rare in those. It had to do with the vertical design RCA has done to it made the vertical circuit failure tolerant so well.

Cheers, Wizard

Hi Guys...

Hey, this is going from bad to worse... from funny to whatever the opposite of funny is :)

Got the durned thing apart, thanks to you guys. Looked at it real close with bright light and big glass and reflowed some solder.

Put it back together, worked perfectly - but only for

10 minute programs before the vert collapsed again. This time much less sensitive... required several good slaps to turn it on/off.

Decided to try once more. Took it apart, reflowed again and did even more areas. Put it back together again.

Dead. Wouldn't turn on. Not front panel or remote. Little bit of noise inserting the cheater cord, but that's it. (Do you younger fellows still call 'em cheater cords? :)

Looked carefully, and either I had broken the thermistor, or broke it while looking. Scrounged another from an old monitor, replaced it and still dead as a doornail.

Googling seems to show thermistors sold by their hot value so can't compare. Old one measured 6 ohms cold, replaced it with one that read about 7 ohms cold.

Just from interest, should it start with an open therm?

Have no schematic, of course. Any suggestions?

Thanks, take care.

Ken

That's just a degaussing thermister, the TV will start and run without it. Check the collector of the horiz output. In standby, the collector should read about 145 volts or so. If it's zero, the smps is dead or shutdown.

John

Hah ! After 25 years, last week I saw my very first vertical failure on a 169. They are very rare. This was a real one, last time it was the degaussing transistor, as it kills vertical during degauss. Technically that one wasn't really vertical failure.

JURB

Yeah, I did mean rare. Anyway, I have a stubborn 169 CTV with intermittent vertical collapse. Already resoldered whole area. Yes I made sure of no glue there!

Cheers, Wizard

I saw one, in only 5-6 years of work...it was a low-value resistor on the input to the vertical IC, and was it fussy! It required the exact value, or the vertical was not corrected. I didn't have the exact value at the time, and tried the next one, and it just didn't do the job. I think the resistor was in the 4.7-5.6 ohm range.

This is almost like a rare bird sighting, isn't it? :-)

Tom

I am pretty sure it was that chassis...I worked on one once, and it worked well when out of the tray, but not when inside. It turned out that the tray was pushing a blob of solder on the edge of the board down, causing a bridge.

Tom