Dell U2412Mb dead (no lights at power button, no back light)

[twinsen]

Hi,

My PSU board is almost the same as https://www.eevblog.com/forum/repair/dell-u2412m-schematics/ except my board is labelled "4H.1GH02.A02".

The first symptom:
The back light and the light at the power button blinks altogether repeatedly (about 2 times a second).  The screen and OSD seems to be okay.  Signal from PC and OSD correctly displayed.

After turned off for a few days:
No sign of life.  No lights at all at the power button.  No back light.  No OSD.

I took it apart and checked the PSU board with power cable (no logic board and other cables connected). The HV part until the 4-leg diode bridge module BD601) is working.  Nothing beyond that part seems to work.  Not sure it's under protected mode by any shorted circuit or being without load.

Couldn't find any schematics of the PSU on the net at all.

Any ideas or suggestions to revive the unit?





Regards,

[singapol]

Sorry no service manual to be found only user manual. It is obvious fron your description that either the main
power supply or other auxilary power is dead.There are protection circuits of course so look for shorts of power transistor ,capacitor or diode.If all these are ok then check capacitors with esr meter. Google MESR100 version2 cheap and good esr meter.

Mesr100V2 :
ttps://www.youtube.com/watch?v=UWNVdfQcXrY

www.ebay.com/bhp/mesr-100