Avante Vertical Issue

[TinCanAlley]

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?

[zeno]

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

[TinCanAlley]

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.

[zeno]

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

[rrrhre2s]

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

[TinCanAlley]

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/...nE%2f%252bI%3d

Originally Posted by rrrhre2s

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

[TinCanAlley]

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!

Originally Posted by zeno

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

[Findm-Keepm]

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

[Findm-Keepm]

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.

[TinCanAlley]

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

Originally Posted by Findm-Keepm

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.

[Electronic M]

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

[TinCanAlley]

Originally Posted by Electronic M

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.