Benq E2420HD backlight issue, black after few seconds

[RichardM]

Hi all

Looking for some help. My Benq E2420hd monitor has developed a problem. Shortly after turn on the screen goes black but the green power led stays on. I have been reading many posts over the last few days but I am none the wiser what may be wrong specifically or what to test. I don't believe it's the backlight tubes themselves as if you turn the monitor on and off again once the PC has booted I can see the windows login screen for a second. Unfortunately I cannot find a service manual for this model.

The voltages look OK, 5v, 3.3v, 24v inverter voltage etc but again I don't have a service manual. I have attached a couple of photos of the power supply board. Diode and transistor checks seem fine in circuit. All electrolytic caps were removed and test OK. Looking for some ideas on what to look for or test.

Richard

[abdulbadii]

Faulty inverter causes the back light not functioning fully
Check high V capacitor on the power supply inc. ESR
Find the fault in the inverter circuit board very nice if got its schematic upload directly here