Samsung 750s problem

[Andrew Howard]

I have an out of warranty Samsung SyncMaster 750s computer monitor that
has suddenly developed a problem.

The display has turned into a sort of warped, pin-cushioned trapezium
shape. It is uneven in that the further you go away from the center, the
more the individual colours separate. It also has some weird vertical
ripples on the left side.(I can upload a picture if necessary). This
developed suddenly, without warning, and without anything being done to it.

It is not the graphics card, as the OSD does the same thing when you
bring it up. It is also not heat dependant, as I have turned it off for a
while to cool, then turned it back on without any change.

I gave it a gentle whack on the top, and it fixed itself for a couple of
hours. It then reverted however, and I can't getting it working properly
again.

I'm thinking it is maybe a dry, or cracked joint. Does anyone have any
ideas where? Or maybe can give an alternate reason?

Also, does anyone know where I can get the schematic for this monitor? I
have done a search of google without result.

Thanks in advance,
Andrew Howard

 

[Andrew Howard]

It is uneven in that the further you go away from the >center, the more the

individual colours separate.

Correction: The colours separate the further away horizontally you get
from the a line down the center.

I have turned the screen completely white, and in doing so I have
discovered the following:
The top left and bottom right go from white, to yellow, to red, in
reasonably sharply defined lines.
The top right and the bottom left go from white, to light blue, to dark
blue.

The same questions remain:

What could be a possible fault, and how would I fix it?

Where could I find the schematic for this monitor (Samsung 750s)?


Thanks again,
Andrew Howard

 

[S]

Given that whacking fixed it once, its a good bet you have a cold solder
joint. To find it you'll have to open it up and examine the underside of
the board. i don't know if you have any experience with this but be warned
there are 25,000 volts on that tube that needs to be discharged. You'll
have to either do it yourself following the various methods found on the web
or take it somewhere. The joint should be fairly obvious once you get under
and have a look. They are typically around transistors or high heat diodes
so look there first and expand the search from there.

 

[JANA]

From your description, this is most likely a cold solder connection, or a
bad connector, or a part that is mechanically intermittent.

If you have the proper soldering tools, and some electronics service
experience, you can open the monitor, and do a search for it. I would start
in the scan amplifier sections, and pin amp sections.

The way that this is done, is the boards are jigged up or removed so that
the underside can be closely inspected. If this is not found by visual
inspection, then the board have to be run in a set-up where they can be
flexed, and prodded to locate the area of the fault. Then sometimes
re-touching up the solder connections in the suspect area will fix it. This
procedure is continued until the faulty solder connection or device is
located.

Considering that from the nature of your question, you are not doing TV or
monitor servicing. I would strongly suggest you give the monitor out for
proper service. There are very serious safety issues involved when working
on these monitors.


--

JANA
_____


I have an out of warranty Samsung SyncMaster 750s computer monitor that
has suddenly developed a problem.

The display has turned into a sort of warped, pin-cushioned trapezium
shape. It is uneven in that the further you go away from the center, the
more the individual colours separate. It also has some weird vertical
ripples on the left side.(I can upload a picture if necessary). This
developed suddenly, without warning, and without anything being done to it.

It is not the graphics card, as the OSD does the same thing when you
bring it up. It is also not heat dependant, as I have turned it off for a
while to cool, then turned it back on without any change.

I gave it a gentle whack on the top, and it fixed itself for a couple of
hours. It then reverted however, and I can't getting it working properly
again.

I'm thinking it is maybe a dry, or cracked joint. Does anyone have any
ideas where? Or maybe can give an alternate reason?

Also, does anyone know where I can get the schematic for this monitor? I
have done a search of google without result.

Thanks in advance,
Andrew Howard