Hello,
My Samsung Syncmaster 794MG monitor intermittently refuses to switch on.
Noted signs/symptoms as below -
1. The monitor LED blinks on and off whenever the monitor is in power on/standby mode.
2. At times, when I press the on button on the front panel, the LED stops blinking and becomes solid green in color; the degauss relay clicks on and off, on screen I see a flicker due to degauss pulse, but, the monitor does not switch on. when the monitor works, it works great (100% satisfied) and hence do not want to put a working monitor in the landfill.
3. The solid Green LED also indicates presence of Video signal on signal cable.
4. Initially, I was thinking that the probable issue is in power supply, either on 14V line or 80V/B+ line. But, what I saw (and also have verified) was, if I disconnect signal cable from computer, after a minute or so the OSD message about not-connected cable flashes on screen.
5. To confirm that the OSD non-connected cable message come on every time, I disconnected signal cable from computer and switched the monitor on/off through a day at random time. Every time, the OSD non-connected cable message was displayed properly. I think his kind of clears the Video preamplifier output and video driver circuits.
6. Since the signal presence is detected, and , OSD message is displayed in absence of cable connection - this rules out the signal detection circuit, power supply (80 V, B+), H and V circuits (blanking, tracing).
7. I am therefore thinking that the problem is in Video preamplifier (LM1236/SAM9286). This chip intermittently fails to communicate with is somehow not able to communicate with uP in the monitor about signal detection status and uP does not switch on the other circuits. The LM1236/SAM9286 does have SCLK and SDA pins that are connected to SCLK, SDA bus.
8. I need the data sheet for LM1236 and SAM9286 to understand how this IC communicates with uP. I have tried searching for these datasheets on the internet, but, no luck so far. If any one can provide me with the datasheet for LM1236 and SAM9286, I will be grateful to them
.
Please let me know in case of any questions.
Warm Regards,
Ravi
My Samsung Syncmaster 794MG monitor intermittently refuses to switch on.
Noted signs/symptoms as below -
1. The monitor LED blinks on and off whenever the monitor is in power on/standby mode.
2. At times, when I press the on button on the front panel, the LED stops blinking and becomes solid green in color; the degauss relay clicks on and off, on screen I see a flicker due to degauss pulse, but, the monitor does not switch on. when the monitor works, it works great (100% satisfied) and hence do not want to put a working monitor in the landfill.
3. The solid Green LED also indicates presence of Video signal on signal cable.
4. Initially, I was thinking that the probable issue is in power supply, either on 14V line or 80V/B+ line. But, what I saw (and also have verified) was, if I disconnect signal cable from computer, after a minute or so the OSD message about not-connected cable flashes on screen.
5. To confirm that the OSD non-connected cable message come on every time, I disconnected signal cable from computer and switched the monitor on/off through a day at random time. Every time, the OSD non-connected cable message was displayed properly. I think his kind of clears the Video preamplifier output and video driver circuits.
6. Since the signal presence is detected, and , OSD message is displayed in absence of cable connection - this rules out the signal detection circuit, power supply (80 V, B+), H and V circuits (blanking, tracing).
7. I am therefore thinking that the problem is in Video preamplifier (LM1236/SAM9286). This chip intermittently fails to communicate with is somehow not able to communicate with uP in the monitor about signal detection status and uP does not switch on the other circuits. The LM1236/SAM9286 does have SCLK and SDA pins that are connected to SCLK, SDA bus.
8. I need the data sheet for LM1236 and SAM9286 to understand how this IC communicates with uP. I have tried searching for these datasheets on the internet, but, no luck so far. If any one can provide me with the datasheet for LM1236 and SAM9286, I will be grateful to them
.Please let me know in case of any questions.
Warm Regards,
Ravi
But today, I’m making an exception here. Why? No idea. Perhaps only because the repair details are still “fresh” in my head… which is ironic, given this is a 16 year old monitor that hardly anyone will care about today. It is new to me, though. 
I picked it up last November from someone on my local Craigslist. It wasn’t very close to where I live, but was close to a family friend that I had to go visit anyways. So after watching the posting on Craigslist for a few weeks and seeing it getting...
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