TDA 1170 Vertical Question

[unix-freak]

Greetings all,

I have a monitor (Videoteknik) that I've been working on...and making
progress - I might add. It was a non working monitor when I got it, now it's
making pretty pictures....except....

When I have still video inputting it...the picture holds steady. When I have
moving/changing video..the picture shift vertically. I can scope the amp
output of the vertical IC and it shifts proportionally to the shifts on the
tube. It equates to 15 lines by my calculations.

The amp input also is shifting. It seems to shift whenever there are changes
from a bright image to a dark..or vice-versa.

I have no schematic...nor can get one. Does this sound like a problem in the
sync seperator circuit...or just a bad vertical cap or two?

Thanks in advance.

 

[Jerry Greenberg]

Check the path of the video signal for any tilt in the vertical
interval. Trace through the sync separator, and follow though to the
vertical sync to the vertical scan generator.

A common fault condition in TV sets and monitors is where there is a
loss of low frequency response in the video or sync path conserning
the vertical sync. This type of fault can occure from this type of
loss.

It is possible that there are some electolytic coupler or decoupler
caps along the paths. An ESR meter to test the caps is the easiest
way to locate the defective ones.

As for schematics, most of the computer monitor companies, and a few
of the no-name TV manufactures will not sell or distribute copies.

Jerry Greenberg
http://www.zoom-one.com