Is the BL_ON (ON/OFF) signal still present when the backlights go out?
12-PIN connector
1- b-dim
2- 13v
3- gnd
4- gnd
5- 5.1v
6- 5.1v
7- a-dim
8- on/off
9- 3.3v
10- led
11- key 1
12- key 2
If I were you, I will use two test lamps to verify if it is the board problem or the lamps problem. Can we see the top side of the board to see if the ballast caps look OK or not, also you should check the high voltage winding of both inverter transformers. https://www.badcaps.net/forum/showthread.php?t=19987
The lamps are ok.
As i told you, there is a problem with OVP (over voltage protection) circuit. One smd resistor and one smd capacitor look damaged and i can't identify their values. Could anyone give me their values or give me a schematic so i can change them?
I have faulty 2233BW monitor and would like to repair the PSU board rather then buy the new one. Capacitors looks good but I changed them with low ESR models and problem is still here. After switching monitor on, CCFL works for about few seconds, then turns off. I can see the picture with flashlight and I hear some squeaking from board. I did some readings while monitor was turned on:
Resistance on inverter secondary trafo: around 1100 Ohm
Voltage on inverter primary trafo: 0 V
Resistance between MOSFET pins: I could't measure it with my meter, scale was on 2 MOhm and it showed up just number 1
Voltage between F301 fuse and ground: around 14.6 V
I have only basic experience with servicing electronics. Can you help me? What's wrong with PSU board? Thank you.
So, I have to replace inverter trafos? I found one on eBay but it's too expensive. The new PSU board costs less then one pair of trafos. Is there any alternative part number?
I dont think there will be an alternative - perhaps wait and see if any more
input and if you can get a cfl bulb for budm's tester. It could be that on a high resistance one the 3% can stretch to 5% . I cant find what it should be but I note on lcdparts.net at the top of the inverter section it says 10%!! which is a bit freaky as we have fixed many sets that have been just over 3% by advisng to change the transformer.
EDIT perhaps message the ebay seller and ask if they can tell you the value of the secondary
resistance.
My experience with Inverter transformers,is that the 3% supposed error limit is certainly not sacrsanct !! I have seen many with more than 5% which were not faulty,and others approaching the 10% also.However Samsung ones do seem to fail at the lower levels,for whatever reason,and in various of their Models it is a standard fault...is this one of the Monitors that has the latter ??
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