Before I start pulling her apart I thought I'd stop by here and see if I'm going in the right direction with the current issue.

As of late, she's been a bit jumpy. The vertical size is twitching. The top and bottom 1/3 or so of the image move about half an inch in and back out. I'm thinking there is something wrong on the vertical module. Something affecting the V size or V lin.

So whatcha think?

Which chassis ?

Either one clean service switch & controls first.
Clean & re- seat module. Contacts can be tightened also.
IIRC there are few electrolytics on flat chassis.
IIRC only put an output in a flat chassis for no vert, never a
board.

Upright chassis you can use 9-92 or 9-147 module.
The newer 9-147 much better. BTW NEVER jump the vert fuse
on an upright chassis !

73 Zeno:smoke:

She's an 25EC58.

When I went over the chassis, I removed all boards, cleaned contacts, boards and deoxit/faderlubed all pots, etc. She's been working fine (other than jailbars) for over a year now. Since the jumping starts pretty much right after turning her on, I don't think it's a heat issue.

The vert module is a 90-83.

OK flat chassis.
A few other things.
If it still has plug in transistors they can give
trouble. Also the terminal strips are soldered to the chassis
on the ends & sometimes along them. They use them for
grounds. They can break loose especially on older sets.
Thats it for easy stuff, try tapping around.....

73 Zeno:smoke:

Try

C719 and C720 4.7 uf

Wet Slug Tantalum, Red capacitors... with one flat end...

Do not use a "regular electrolytic" capacitors they will cause linearity problems...

They are old enough to be going bad...

rrrhre2s

My Zenith tech topics suggests for the 25EC58 chassis to resolder all the vertical output transformer leads where they meet chassis connections - particularly those on the top of the chassis. The symptoms described in the Tech Topics is vertical pull up from the bottom, with convergence affected.

I found this at Mouser. Is it correct? I sure wish there was a place local that carried such things. Gets tiring ordering a couple bucks worth of parts and paying triple in shipping.

http://www.mouser.com/ProductDetail/Kemet/T322B475K015AS/?qs=sGAEpiMZZMtZ1n0r9vR22dApefZuZ5tWHmynrgnE%2f%25 2bI%3d

Try

C719 and C720 4.7 uf

Wet Slug Tantalum, Red capacitors... with one flat end...

Do not use a "regular electrolytic" capacitors they will cause linearity problems...

They are old enough to be going bad...

rrrhre2s

She keeps her convergence with the twitching. Her top comes down a bit as the bottom comes up a bit. As it gets closer to the center of the screen, it gets less noticeable.

Thanks

My Zenith tech topics suggests for the 25EC58 chassis to resolder all the vertical output transformer leads where they meet chassis connections - particularly those on the top of the chassis. The symptoms described in the Tech Topics is vertical pull up from the bottom, with convergence affected.

I'll pull and reseat the transistors. Need to get his fixed as I have the final season of SWAT to watch as well as Movin' On.

Thanks!

OK flat chassis.
A few other things.
If it still has plug in transistors they can give
trouble. Also the terminal strips are soldered to the chassis
on the ends & sometimes along them. They use them for
grounds. They can break loose especially on older sets.
Thats it for easy stuff, try tapping around.....

73 Zeno:smoke:

Here's all the tech topics for the flat chassis - three pages, something on all of them.

I found this at Mouser. Is it correct? I sure wish there was a place local that carried such things. Gets tiring ordering a couple bucks worth of parts and paying triple in shipping.

http://www.mouser.com/ProductDetail/Kemet/T322B475K015AS/?qs=sGAEpiMZZMtZ1n0r9vR22dApefZuZ5tWHmynrgnE%2f%25 2bI%3d

Those would probably work.

If you have electrolytic capacitors you can try them it will stop the jumping just height and linearity will no adjust properly .

rrrhre2s

Here's all the tech topics for the flat chassis - three pages, something on all of them.

Were these sent to Zenith Dealers? I never saw a format that gave credit like that before?:thmbsp:

If so, the RCA dealers I worked for did not get anything like this.

Do you have any for 1964-72 color sets? :scratch2:

There was a guy selling yearly subscriptions to a repair list. He also sold one for the computer (386 - 486 Days). This was almost 22 years ago before I quit servicing TV's to make a living.

Used to carry them in a loose leaf binder for home service calls, sometimes saved loading up the set and transporting it back to the shop.

I now wish I had not gotten rid of them when I closed the shop in 1996.

rrrhre2s

Were these sent to Zenith Dealers? I never saw a format that gave credit like that before?:thmbsp:

If so, the RCA dealers I worked for did not get anything like this.

Do you have any for 1964-72 color sets? :scratch2:

They are from Zenith's Tech Topics - I have an incomplete set from 1970 to about 1978. Doug (DRH4683) also has some - probably more than I do. Zenith provided these to authorized repair centers on a monthly basis, and we always picked up a stack at the Zenith training seminar. I went to a total of 2, but my father went to several dozen Zenith training seminars, and some RCA, NAP and even Sencore seminars. I got my Dad's collection of service data from his shop - mostly older stuff, as he sold anything newer than 1998 to another service shop when he retired.

RCA had their "Goldenrod" supplements - orangish-gold paper supplements to their service literature. I've got from CTC53 - CTC90. Later, Thomson issued complete field trouble reports - three types - TV, VCR, and Projection. I have all three for the CTC175-CTC203 era, along with all of their ESI disks and manuals, along with a Chipper Checker suite - almost useless today.

I've got Sony, Hitachi, LG, Motorola, Zenith, Philco, and Panasonic/technics, Samsung. NAP and RCA data, much more than Sams covered - and I still have my Sams (sets 100-1900) Anything newer from Sams, I don't have....

And thanks to Bryan Gadow, I even have Sears service manuals for 70s-late 80s stuff, but no index.

Cheers,

There was a guy selling yearly subscriptions to a repair list. He also sold one for the computer (386 - 486 Days). This was almost 22 years ago before I quit servicing TV's to make a living.

Used to carry them in a loose leaf binder for home service calls, sometimes saved loading up the set and transporting it back to the shop.

I now wish I had not gotten rid of them when I closed the shop in 1996.

rrrhre2s

There was a company called KDTV that had a database of repair tips for about 70 bucks, but 60 percent of it was useless crap like Sams cross references, model-to-chassis crosses, and parts subs. The remaining 40% was so Curtis mathes and Colortyme loaded that you got about 2000-3000 actual tips, and many were duplicates. They gave renewal credits for tips submitted, but no quality checking on the tips that were submitted, making for a very watered-down database. Repair World was okay, but got NAP heavy. Our best resource was other shops in our area, sharing helpful tips in phone conferences and a Sams-borrowing library. If you fixed a set, you marked up the Sams with the problem and cure. Some Sams had additional pages added - those were the problem sets like the System 3s, the GE AA/AB/AC chassis sets, and the RCA CTC175-185 sets with the EEPROM and tuner troubles.

Someone recently sent me a postcard about another online resource for an HDTV repair database - submit 20 tips and get a trial subscription. What a waste - board swapping isn't troubleshooting, and a database supporting that is not needed. Enough free resources exist - Vk, AVS forum and others for example.

Cheers,

Found something interesting. Of course it complicates things for me, but interesting nevertheless.

The other night I was watching the set and it had the usual twitching in vertical height (top and bottom). Then this line appeared about 6" from the bottom and it was moving up and down about an inch. It was transparent, so I thought it was the program material. I paused it, but the line still was there. It wasn't perfectly straight. I figured it was the same issue, just a different effect.

After enduring it as long as I could, I was about to shut the set off. As I was about to shut it off, something told me to mess with the vertical hold. So that's what I did. As soon as I touched the v-hold, it started rolling like you'd expect. I then rotated it back and forth a few times and then adjusted out the rolling. After the picture stopped rolling I noticed the line was gone and the twitching stopped. Of course this didn't last too long. A few minutes later the twitching started again, but not as bad, and the line was reappearing, but lower on the screen. A turn of the v-hold again took care of it again for a short period.

So I can temporarily fix it with a turn of the v-hold. Does this indicate a problem with the pot, or is the change in resistance by turning the pot causing the vertical module to get the electronic version of a spit and smack?

Thanks

The pot may have in whiskers or conductive dirt inside....You should clean it.

The pot may have in whiskers or conductive dirt inside....You should clean it.

The pot had already been cleaned with deoxit and finished off with fader lube. I did this twice to it last year. I'm pretty certain its as clean as it's going to get.

My brother mentioned that it might be the change caused by turning the pot that causes the capacitors on the v-module to change value. The in turn creates a temporary fix for the failing capacitor(s).

So I think I'll just suck up the $6 shipping and get the two replacement tantalum caps on the v-module. Hopefully it will fix the issue.