I lowered it from 100 to 65% and it indeed helped, but after a couple of months the issue returned... I continued to lower the brightness, but it helped only for a couple of hours at most, then I needed to lower it further... Turning the monitor off and waiting for it to cool down also helped for a short time, after which it continued to black out every 10-30 sec... I decided to take the monitor apart and look at the power board, and indeed saw 3 bulged capacitors.

I bought new replacement caps and went to a professional (soldering is not among my skills), and he replaced all the caps on the power board except the biggest one for high voltage, since it seemed fine and rarely goes bad according to my research. But he mesured it's capacitance and saw it was 120 uF instead of 150, but I decided to see if replacing every other caps fixed the issue (I also didn't have the replacement for the big cap)...

Unfortunately it did not, the monitor continued to black out periodically, I continued to lower the brightness for several hours untill I hit the bottom and at the end the monitor started to fade frantically and after a short time blacked out for good...

I replaced the last capacitor on the power board (150 uF 450 V), but it didn't help, my monitor now is permanently black and doesn't turn on at all (the indicator light turnes white and then red after a minute). And I can see the image on the screen with a flashlight, so it is a backlight issue.

I measured the output voltages from the PSU board to the backlight on CN801 connector (see my 2nd picture below). It's 29.3 V on contacts 3 and 4 (red wires), the rest are 0.

• I get the same voltages readings with the power cable plugged in, regardless of whether the backlight is connected to the PSU or not, and whether I turn the monitor on or off with the button (it just drops from 29.3 to 29.2 V when I turn it off).

Someone who took apart the same monitor mentioned on another forum that each wire goes to a pair of LED strips with 10 LEDs on each strip, and the voltage he measured was about 60 V. Those findings correspond to the reference data I received from BenQ tech support. Apparently the voltages I get are half of the nominal...

Does this mean that my power board is faulty? If it is, how can I pinpoint the faulty component on the board? Or the problem is rather the backlight LED strips failure as many people clame? This is a great monitor I payed a lot of money for and I'd really like to fix it instead of throwing it away...

Thanks.

Connections:

From the buttons in the frame to the mother board:

From the mother board to the PSU board:

(also, see CN701 on the PSU board on the 3rd and 4th pics from the top)

From the PSU board to the display:

T-con board:

Reference data:

⟐ Commented April 03, 2026 at 9:26 MST