I bought this p2210f dell monitor to fix. Schematic is the same as p2210.
Behaviour is that monitors comes on but then backlight switches off almost instantly. If I look with flashlight I can still find the "No signal message". So definitely a backlight issue. Trying to advance the issue I proved that the protection circuit is switching off the backlight by shorting out C3 and resistor to disable the INL chip then re enable by removing the short.
This is where it gets interesting. When I disassembled the monitor to solder leads on c3 capacitor I noticed the backlight flickered at first but mostly it would stay on. What I had expected was that the backlight would turn off as previous but that didn't happen. So I thought what's different.. What was different was that the data cable from video processing board was disconnected from the LCD.
Sure enough when I put the monitor back together, monitor would come on and backlight switched off in a second. Now I could bring the backlight back on by shorting the leads I soldered on C3 and removing the short thus re-enableing INL chip.
My question is what would cause this strange behavior?
Behaviour is that monitors comes on but then backlight switches off almost instantly. If I look with flashlight I can still find the "No signal message". So definitely a backlight issue. Trying to advance the issue I proved that the protection circuit is switching off the backlight by shorting out C3 and resistor to disable the INL chip then re enable by removing the short.
This is where it gets interesting. When I disassembled the monitor to solder leads on c3 capacitor I noticed the backlight flickered at first but mostly it would stay on. What I had expected was that the backlight would turn off as previous but that didn't happen. So I thought what's different.. What was different was that the data cable from video processing board was disconnected from the LCD.
Sure enough when I put the monitor back together, monitor would come on and backlight switched off in a second. Now I could bring the backlight back on by shorting the leads I soldered on C3 and removing the short thus re-enableing INL chip.
My question is what would cause this strange behavior?
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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