Samsung TFT monitor 713BM

C

Clyde

Guest
Hi. This monitor has a strange fault. When switched on without signal
the screen illuminates and the "check signal cable" display moves around
the screen as it should. However, when I connect a signal, I get a brief
screen of garbled lines (very brief indeed) then the backlights go out.
The power LED also goes off, though it comes back on again, but with no
display.

I have checked the various capacitors on the PCB with an ESR meter, also
the power supply in the same way. The voltages coming from the power
supply appear correct.

Has anyone experienced this fault? The RGB signals go to a SE7888 i.c.
which appears to drive the screen. I assume at least part of this is
working due to the no signal display being good. Is it possible that
something has failed internally in this i.c.? Could the solution be
simpler than that (my experience has shown these chips seldom fail)

Does anyone have one laying around in a scrap monitor?

Thanks.
 
"Clyde" <mkdrummeyNOSPAMPLEASE@hotmail.com> wrote in message
news:4H5Do.28960$a32.18147@newsfe21.ams2...
Hi. This monitor has a strange fault. When switched on without signal the
screen illuminates and the "check signal cable" display moves around the
screen as it should. However, when I connect a signal, I get a brief
screen of garbled lines (very brief indeed) then the backlights go out.
The power LED also goes off, though it comes back on again, but with no
display.

I have checked the various capacitors on the PCB with an ESR meter, also
the power supply in the same way. The voltages coming from the power
supply appear correct.

Has anyone experienced this fault? The RGB signals go to a SE7888 i.c.
which appears to drive the screen. I assume at least part of this is
working due to the no signal display being good. Is it possible that
something has failed internally in this i.c.? Could the solution be
simpler than that (my experience has shown these chips seldom fail)

Does anyone have one laying around in a scrap monitor?

Thanks.
Click to expand...
Is the computer perhaps set to a display resolution that the monitor doesn't
support? I have some older LCD/TFT monitors that don't support over
1024x768 (one doesn't support over 800x600!), and they simply will not show
video at anything higher.
 
On 12/11/2010 08:19, Brenda Ann wrote:
"Clyde" <mkdrummeyNOSPAMPLEASE@hotmail.com> wrote in message
news:4H5Do.28960$a32.18147@newsfe21.ams2...
Hi. This monitor has a strange fault. When switched on without signal
the screen illuminates and the "check signal cable" display moves
around the screen as it should. However, when I connect a signal, I
get a brief screen of garbled lines (very brief indeed) then the
backlights go out. The power LED also goes off, though it comes back
on again, but with no display.

I have checked the various capacitors on the PCB with an ESR meter,
also the power supply in the same way. The voltages coming from the
power supply appear correct.

Has anyone experienced this fault? The RGB signals go to a SE7888 i.c.
which appears to drive the screen. I assume at least part of this is
working due to the no signal display being good. Is it possible that
something has failed internally in this i.c.? Could the solution be
simpler than that (my experience has shown these chips seldom fail)

Does anyone have one laying around in a scrap monitor?

Thanks.

Is the computer perhaps set to a display resolution that the monitor
doesn't support? I have some older LCD/TFT monitors that don't support
over 1024x768 (one doesn't support over 800x600!), and they simply will
not show video at anything higher.
Click to expand...
Hiya, it's a 17 inch monitor, about years old. I believe it's native
resolution is 1280x1024 which is what the computer is currently set at.
I will just try it at VGA resolution but the symptoms have been the same
right from boot up.

I am not sure about the i.c. and to replace it will cost me over Ł20,
which is possibly more than the monitor is worth. The i.c appears to be
the same as SE7889, it looks to be a Samsung part. Have just got hold of
a circuit diagram for this section so will be checking a few voltages
and signals around this IC but I have a feeling it's faulty on the input
side.
 
On Fri, 12 Nov 2010 07:05:34 +0000, Clyde
<mkdrummeyNOSPAMPLEASE@hotmail.com> wrote:

Hi. This monitor has a strange fault. When switched on without signal
the screen illuminates and the "check signal cable" display moves around
Click to expand...
That's a healthy sign.

However, when I connect a signal, I get a brief
screen of garbled lines (very brief indeed) then the backlights go out.
Click to expand...
That could indicate that you supply an out of range signal.
Either too much resolution or too high a refresh rate.
(640 x 480 should be fine, but at more than 60 Hz some LCDs still
prefer to stay asleep :)

--
Kind regards,
Gerard Bok
 
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