Mitsubishi CS-3515R Television

[Don]

I actually asked about this set quite some time back, but unfortunately have
lost me notes on the thread........

The set is a Mitsubishi CS-3515R (manufactured Oct 1992). When first turned
on, the picture is collapsed into a horizontal line midway between the top
and the bottom of the screen. Based on varying intensity and strong green
from the menu items (e.g. channel, volume, etc), it seems the horizontal
scan is fine. Sometimes after 5-30 minutes (i.e. the set "warms up") the
picture expands to full screen. Today when I was toying with it, the
picture would occasionally snap to full screen for less then a second and
then collapse into the horizontal line.

Given this the above, I am guessing:

1) A case of dried electrolytics in the vertical section.

2) Bad IC in vertical section.


Now for the questions:

1) Is this "collapsed" picture a relatively common problem?

2) If it is, any estimate on cost to repair?

3) Is it user serviceable (i.e. replace caps C101, C02, etc)?

4) Given the set is in otherwise very good condition, is it worth fixing?

Thanks!!

Don

 

[Art]

Actually using an ESR meter you will find a fairly large number of caps that
may require replacing. The actual cost of those items are not all that much.
How was the picture quality before the vertical finally failed, if it was
good, indicating the CRT is probably in fair shape, it may be worth while
attempting the repairs. May want to acquire a Sams Photofact for the set, if
available, or a schematic, it will help you sort out what circuit you are
troubleshooting. Vertical Output should be a LA7837 or LA7838, a common
part. Also check for any supply resistors to the vertical circuit that may
have overheated or changed value.

 

[Phil Bowser]

Given the fact that the set "sometimes" has a full picture, I believe
you need neither an IC or capacitors, although replacement of the
electrolytic capacitors around the vertical output would be good preventive
maintenance.

Sounds to me like the solder connections have cracked around the pins of
the vertical output IC (very common) and / or other components in that area.
As you so adequately put "toying with it" - you probably momentarily flexed
the circuit board or induced some physical impact that allowed the
connections to "make" and allow the set to develope a full picture for a
moment or so. If you're comfortable with a soldering iron, disconnect AC
power to it and have a good look at the pins of the IC with a magnifier, and
resolder as needed.

 

[Don]

Art,

Sounds like not too bad of a weekend project!

Thanks!!

Don

 

[Don]

The picture was pretty good. That's why it seems such a shame to junk the
set if it is something relatively easy to fix.

Thanks again!

Don

 

[Don]

Phil,

Maybe a poor choice of words in using "toying". Didn't actually have the
set apart (or whacking it with a 2x4! More case of channel changing and
video source changing.

Between your response and Art's, I might take a peek inside. I'm more of a
digital type, but certainly know how to read a schematic, trace circuits,
and which end of the soldering iron to hold!

Thanks!


Don