My brother gave me this monitor after it stopped working for him in hopes I could repair it and find it a new home.
The display turned on when I hit the power button for about a second and then immediately went dark. It appeared the backlights were shutting down because the monitor continued to function as I could see the desktop using a flashlight.
So I suspected there was a problem in the inverter or one of the ccfl's.
There were five electrolytic capacitors on the inverter board:
(3) 220uF 25V Elite capacitors
(2) 47uF 25V Lelon capacitors
I went ahead and tried replacing the 3 Elite caps with some panasonic FC's I had lying around but this didn't change anything. I dont have anything to replace the 2 Lelon caps with, but I do plan to replace all caps in this monitor at one point.
Then I measured the 3 inverter transformers and everything seemed ok there.
Next I tried resoldering all the legs of the inverter transformers and surrounding devices just incase there were any bad solder joints. Still no improvement.
I noticed the inverter is using the oz964gn pwm controller chip. Working from past experience, I temporarily installed an LED From pin 10 to ground. This forces pin 10 (Voltage Control Loop Compensation Pin) to around its nominal operating voltage. If I understand correctly, this fools the chip into believing there is no problem (ie over/under voltage or current) in the inverter.
Here is the data sheet incase anyone wanted to see it: http://pdf1.alldatasheet.com/datashe...C/OZ964GN.html
Anyways, by installing this LED, I was able to get the monitor to work properly. This leads me to believe that there is a problem in the inverter... either a over/under voltage or current condition OR a false positive for one of those conditions due to a problem in the detection circuitry. Not sure which one it is, but I figured it would be worth mentioning that with the LED installed, the Monitor operates wonderfully i.e great picture and great illumnination.
So that all brings me to where I am at now... due to how this monitor is assembled, I can't really be making any online readings so further troubleshooting is going to be difficult.
Anyone have any ideas? I suppose it could be that one of the ccfl's is getting old and just pulling to much current but I'm not sure how to go about determining this. Or should I try replacing the 2 Lelon caps?
I have included top and bottom picture of both the inverter and power supply. Not the best quality but I suppose they are better than nothing. You'll notice a jumper wire installed on the inverter - that runs out to the LED I was talking about.
Any advice is appreciated.
The display turned on when I hit the power button for about a second and then immediately went dark. It appeared the backlights were shutting down because the monitor continued to function as I could see the desktop using a flashlight.
So I suspected there was a problem in the inverter or one of the ccfl's.
There were five electrolytic capacitors on the inverter board:
(3) 220uF 25V Elite capacitors
(2) 47uF 25V Lelon capacitors
I went ahead and tried replacing the 3 Elite caps with some panasonic FC's I had lying around but this didn't change anything. I dont have anything to replace the 2 Lelon caps with, but I do plan to replace all caps in this monitor at one point.
Then I measured the 3 inverter transformers and everything seemed ok there.
Next I tried resoldering all the legs of the inverter transformers and surrounding devices just incase there were any bad solder joints. Still no improvement.
I noticed the inverter is using the oz964gn pwm controller chip. Working from past experience, I temporarily installed an LED From pin 10 to ground. This forces pin 10 (Voltage Control Loop Compensation Pin) to around its nominal operating voltage. If I understand correctly, this fools the chip into believing there is no problem (ie over/under voltage or current) in the inverter.
Here is the data sheet incase anyone wanted to see it: http://pdf1.alldatasheet.com/datashe...C/OZ964GN.html
Anyways, by installing this LED, I was able to get the monitor to work properly. This leads me to believe that there is a problem in the inverter... either a over/under voltage or current condition OR a false positive for one of those conditions due to a problem in the detection circuitry. Not sure which one it is, but I figured it would be worth mentioning that with the LED installed, the Monitor operates wonderfully i.e great picture and great illumnination.
So that all brings me to where I am at now... due to how this monitor is assembled, I can't really be making any online readings so further troubleshooting is going to be difficult.
Anyone have any ideas? I suppose it could be that one of the ccfl's is getting old and just pulling to much current but I'm not sure how to go about determining this. Or should I try replacing the 2 Lelon caps?
I have included top and bottom picture of both the inverter and power supply. Not the best quality but I suppose they are better than nothing. You'll notice a jumper wire installed on the inverter - that runs out to the LED I was talking about.
Any advice is appreciated.
Comment