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PostPosted: Wed Jul 20, 2011 5:20 pm    Post subject: Samsung SyncMaster 1100df CRT monitor: pwr LED OK but...

I have a Samsung SyncMaster 1100df CRT monitor that produces no picture but much of the circuits seem to be 'okay' (IME and knock wood, of course. I only have a DMM to work with -- no o'scope).

The main power button green LED, which either blinks (no source plugged in) or steady on (signal) stays steady despite no signal inputted. This is strange. But, if there is no signal, the screen should STILL display a message indicating see "No Connection, Check Signal Cable".
The HV does not seem to kick in with the usual cold-start bang (typical of CRTs). I haven't explored the HV section yet because it is more inconveniently embedded on the middle of PCB (hard to reach in w/o pulling out the PCB).

But ...

Of all the non-HV PSU sections ck'd, all seems okay. The logic and control voltages (+5, +12) seem to be fine. All the ICs I've ck'd thus far seem to be getting clean power. The IC that sends the 'data/signal present' signal seems to be okay.

Again, the really weird bit is the steady on pwr LED. There is no signal, so it should be blinking (even with signal inputted, I get no picture).

The problem happened catastrophically (w/o warning or impending disaster -- i.e., increasing glitch rate) . No other sign of evil smell, strange noises, etc. When one pwrs on, one can hear a very quiet whistle of switching PS devices turning on. I have a smaller CRT Samsung (working) which also emits these.
The service manual is here:

Thx for any offer of help!

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