Samsung LCD monitor slow to start up (Crystal aging?)

[Richard Thomas]

I am trying to fix a 4-year old Samsung SM171P (aka GH17P) LCD monitor that can take
several minutes to achieve initial synchronisation to either VGA(DSUB) or DVI inputs
- it just sits there alternating its power light orange/green. Once sync is achieved
it works fine.

I have the service manual / schematics and have been probing around the main PCB. I
believe that the problem is that the monitor struggles to get past the point where
the main GM5020 graphics processing IC measures incoming HSYNC/VSYNC frequencies and
tries to match them to a mode that it supports. I'm hoping its not the GM5020 as that
is a PBGA package so can't be replaced by hand.

I am wondering if the problem is that the crystal frequency has drifted as it ages -
I see from the parts list that the crystal is unusually fine tolerance 30ppm:
CRYSTAL-SMD;24MHz,30ppm,28-ABX,16pF,50ohm

Anyone had similar experience with crystals / Samsung monitors / GM5020 IC?

Anyone know of companies in the UK that can supply specific made-for-Samsung
components? (The equivalent of partsearch.com in the US?)

All help appreciated,

Richard

 

[Mike Berger]

Crystals are very reliable, and in this case the drift would
not be enough to take minutes to sync. It sounds a lot more
like a component that fails when too cold or uncharged.

 

[Guest]

sounds like a crappy capacitor somewhere.

 

[JANA]

Get an ESR meter, and check all the caps in the monitor. You will most
likely find some that are high in ESR.

As for having any proprietary parts for your monitor, they will be very
difficult to find.

--

JANA
_____


I am trying to fix a 4-year old Samsung SM171P (aka GH17P) LCD monitor that
can take
several minutes to achieve initial synchronisation to either VGA(DSUB) or
DVI inputs
- it just sits there alternating its power light orange/green. Once sync is
achieved
it works fine.

I have the service manual / schematics and have been probing around the main
PCB. I
believe that the problem is that the monitor struggles to get past the point
where
the main GM5020 graphics processing IC measures incoming HSYNC/VSYNC
frequencies and
tries to match them to a mode that it supports. I'm hoping its not the
GM5020 as that
is a PBGA package so can't be replaced by hand.

I am wondering if the problem is that the crystal frequency has drifted as
it ages -
I see from the parts list that the crystal is unusually fine tolerance
30ppm:
CRYSTAL-SMD;24MHz,30ppm,28-ABX,16pF,50ohm

Anyone had similar experience with crystals / Samsung monitors / GM5020 IC?

Anyone know of companies in the UK that can supply specific made-for-Samsung
components? (The equivalent of partsearch.com in the US?)

All help appreciated,

Richard