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-   -   Vertical deflection timing cap (http://www.videokarma.org/showthread.php?t=276536)

timmy 04-01-2024 10:07 AM

Vertical deflection timing cap
 
In a solid state b&w TV set is there a vertical timing capacitor that is not an electrolytic cap. If it does and the cap opens or shorts would that likely stop the horizontal deflection as well. This tv I’m working on has an ic chip that controls both I’m trying to determine if the ic is bad or a possible cap. It had vertical but was flickering in and out then both went dead.

zeno 04-01-2024 01:37 PM

Yes. A B&W will have an osc stage, one for Vert & one for Hoz.
there will also be hold controls. Many varieties so need more info
& symptom to help if you need it.

BTW Betters color sets @1975 ++ have a master osc for both V & H
The master freq gets divided down or counted down so both can go
out at the same time. Sylvania was first, called it a think chip &
was on the GT-Matic line. Very stable, reliable & saved parts. Cant beat that !

73 Zeno:smoke:
LFOD !

Yamamaya42 04-01-2024 01:49 PM

Exactly, W/O further information, it's quite impossible to offer any guidance beyond wild speculation, it's true that many sets of the era did have linear ICs at the heart of the main board that did most of everything, W/O knowing the make, or MO#, or perhaps the IC# in question, it is kind of like flying blind.

old_tv_nut 04-01-2024 02:35 PM

I don't think any TV was designed so that failure of the sync IC would stop the horizontal sweep from running (a sure way to burn up horizontal outputs and/or flybacks). The first IBM PC color monitor did that, resulting in a lot of failures when they were turned on without connecting to the video/sync output of the PC. TV designers laughed at that blunder. It is conceivable that some sets had a safety feature to prevent burning a line into the CRT if vertical failed, but I can't point to one myself.

Yamamaya42 04-01-2024 02:42 PM

Quote:

Originally Posted by old_tv_nut (Post 3256395)
The first IBM PC color monitor did that, resulting in a lot of failures when they were turned on without connecting to the video/sync output of the PC. TV designers laughed at that blunder..

:tears: :tears::yikes:

Please Don't remind me of that horror! :O

First job out of HS, Computer repair shop... I SAW IT! :yes:

timmy 04-01-2024 04:12 PM

1 Attachment(s)
Here’s what I’m working on Sinclair mtv1 and the ic is not available or interchangeable found nothing online so I’m trying to rule out if the ic is bad or not. This is an electrostatic crt tv.

timmy 04-01-2024 04:16 PM

1 Attachment(s)
This is a rough schematic of the deflection ic. Don’t know if this can be matched.

zeno 04-01-2024 06:46 PM

Looks like it has a TI symbol on the IC.What are the numbers ?
You can also check the pins for the VCC ( B+). Probably 12 VDC. And see if it
gets real hot or stays cold when on a while.
BTW IIRC shango did one a few yrs ago.

Zeno

timmy 04-01-2024 06:53 PM

Quote:

Originally Posted by zeno (Post 3256400)
Looks like it has a TI symbol on the IC.What are the numbers ?
You can also check the pins for the VCC ( B+). Probably 12 VDC. And see if it
gets real hot or stays cold when on a while.
BTW IIRC shango did one a few yrs ago.

Zeno

It uses 4.8v and staying on awhile it don’t get hot or warm.

timmy 04-02-2024 04:32 AM

Quote:

Originally Posted by zeno (Post 3256400)
Looks like it has a TI symbol on the IC.What are the numbers ?
You can also check the pins for the VCC ( B+). Probably 12 VDC. And see if it
gets real hot or stays cold when on a while.
BTW IIRC shango did one a few yrs ago.

Zeno

How could I find out if Shango did one I looked but there’s alot of his videos.

Yamamaya42 04-02-2024 06:02 AM

https://www.youtube.com/watch?v=meXXNk4A9gM

timmy 04-02-2024 07:03 AM

Quote:

Originally Posted by Yamamaya42 (Post 3256419)

I seen that one and all she does is rips everything apart and that’s it.

Yamamaya42 04-02-2024 07:25 AM

https://www.guenthoer.de/doku/service-sinclairmtv1.pdf

From what it seems, the ICs are proprietary, and quite unobtainium, and aside from getting lucky and finding a bad cap/resistor or connection fault, chances of it working are very low.

timmy 04-02-2024 07:41 AM

Quote:

Originally Posted by Yamamaya42 (Post 3256421)
https://www.guenthoer.de/doku/service-sinclairmtv1.pdf

From what it seems, the ICs are proprietary, and quite unobtainium, and aside from getting lucky and finding a bad cap/resistor or connection fault, chances of it working are very low.

Yes I know they are not available and specifically designed for this set. The 3 volt regulator is working and battery voltage is where it should be and has a ground so I still can’t rule out anything else as I don’t want to condemn the ic unless I am sure.

Yamamaya42 04-02-2024 08:07 AM

From what I have seen, this unit has a very bad reputation of self destruction due to battery leakage and even perhaps bad caps, where the electrolyte has attacked and destroyed the connectors on and in between the boards, and possibly traces on the board, and interconnects between the top and bottom of the boards.

All should be inspected under a good microscope.


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