Samsung SyncMaster 245B Plus (Manufactured June 2008)
PSU: BN44-00195A
Inverter: BN44-00136B
Monitor stopped working a year ago, I removed yellow glue, replaced all secondary side electrolytic capacitors with United Chemicons LXZ, One 2200uF/10V with new Samwha WL and one 1000uF/10V with Hitano EXR. Primary side capacitor (82uF/450V) is, according to my capacitance meter, OK, but I replaced it with 100uF/450V Hitano EHP.
Monitor worked well over a one year. Only inverter transformers produced light buzzing sound, hearable in ~10cm distance.
Now When I try increase brightness level over 60%, monitor momentarily stop doing buzzing and backlight level is, also momentarily, increased. Then backlight turns off. Picture is still there (visible with flashlight). When I decrease brightness level under 60% and restarting the monitor, backlight is back. Buzzing sound is back too.
I measured output from PSU to inverter.
- 24V is steady 24,1V (at any level of backlight)
- ON/OFF is 4,4V (at any level of backlight)
- A-DIM is 2,9V (at any level of backlight)
- EX-PWM I think, that this is backlight level regulation. Voltage is increasing as I increasing brightness level. 2,6V is 60% brightness level. Above 2,6V on this pin backlight shuts down.
I Tried replace two 470uF/35V capacitors on inverter board (BN44-00136B), but without success.
I measured transformers according this post
I got:
1-4: 5MΩ
1-2 and 3-4: 8MΩ
PSU: BN44-00195A
Inverter: BN44-00136B
Monitor stopped working a year ago, I removed yellow glue, replaced all secondary side electrolytic capacitors with United Chemicons LXZ, One 2200uF/10V with new Samwha WL and one 1000uF/10V with Hitano EXR. Primary side capacitor (82uF/450V) is, according to my capacitance meter, OK, but I replaced it with 100uF/450V Hitano EHP.
Monitor worked well over a one year. Only inverter transformers produced light buzzing sound, hearable in ~10cm distance.
Now When I try increase brightness level over 60%, monitor momentarily stop doing buzzing and backlight level is, also momentarily, increased. Then backlight turns off. Picture is still there (visible with flashlight). When I decrease brightness level under 60% and restarting the monitor, backlight is back. Buzzing sound is back too.
I measured output from PSU to inverter.
- 24V is steady 24,1V (at any level of backlight)
- ON/OFF is 4,4V (at any level of backlight)
- A-DIM is 2,9V (at any level of backlight)
- EX-PWM I think, that this is backlight level regulation. Voltage is increasing as I increasing brightness level. 2,6V is 60% brightness level. Above 2,6V on this pin backlight shuts down.
I Tried replace two 470uF/35V capacitors on inverter board (BN44-00136B), but without success.
I measured transformers according this post
I got:
1-4: 5MΩ
1-2 and 3-4: 8MΩ
Attached Files