Re: hanns g hh251 not recognizing input

Well, I removed the fuse. The monitor still went to sleep with and without a computer plugged in. I checked the MOSFETs and the resistance between the source and drain is in the megaohms for all four. I tried testing the VGA port and saw that the R and G ports are open circuit to their respective R and G grounds. The B port looks ok (it reads 74.7 Ohms to B ground which seems to match the schematic budm posted). So it is probably a case of ESD. All the diodes seem to be ok though. I don't think I want to go to the effort of troubleshooting...

Re: hanns g hh251 not recognizing input

I replaced the diode that I thought was shorted, but the good one appears shorted once it is soldered in the circuit as well... I can't think of any useful circuit where a diode would be shorted in both directions, but I'm not too experienced in electronics.

I may have to amend my previous post. The clicking and flashing backlight now only occurs when the resistor is holding the backlight control high. The clicking goes away when the resistor holds PSON high. The 12V is stable and reading what it should when the PSON is high....

Re: hanns g hh251 not recognizing input

Ok, so I tried what Rtech suggested. I put a 1k resistor between the 5.2V and O/F pins (I also tried putting PSON high, but that didn't do anything that I could see). I heard a slight, regular clicking and the backlight flashes with the clicking sound. When I removed the resistor, the clicking sound remained, but the backlight didn't flash. The 5.2V stays constant for all of this, but the voltage on the input of the 12V regular fluctuates between 5-7V when the resistor is connected and 9-11.5V when the resistor is not connected. Somehow the...

Re: hanns g hh251 not recognizing input

That is a great idea! I'll give that a try tonight and let you know what I find.

Re: hanns g hh251 not recognizing input

Thanks for the help! I did take a look at those other posts, angel-boy, but didn't seem to have the same issues as described. Here are the pictures of the PSU and logic board. I did some more probing and found a diode on the back of the PSU that appears to be shorted according to my multimeter (there is a red arrow pointing at it). Could that really be the issue that sends the LCD to standby? All the fuses I could find on both boards seem fine....

Hello!

I recently acquired an LCD panel that the lab next door was throwing away. The only historical information I had was a post-it note with the word "Broken" on it. I took it home and powered it up. The green light comes on, a message saying "No input detected" appears on the panel for a few seconds, and it goes straight to standby with the power light turning amber. I tested the vga input with a few computers. The display is recognized by the computers, so I figured the logic board is ok.

I proceeded to take it apart and test the main capacitor...

Re: New Members - please post your introductions here

Greetings from Minnesota. I'm hoping to repair a LCD I picked up.