[RESOLVED] Monitor PCB Repair

Thread Starter

aviioo

Joined Aug 27, 2020
8
Hello,

Today I made a really stupid mistake and forgot to unplug my power cable from my monitor while turning it into landscape format. I’m not exactly sure what happened, but I’m guessing that due to the connectors being bent they had bad contact to the plug and this resulted in a spark. There was definitely a spark like sound and I tried multiple cables, which all didn’t work. When I plugged in the second cable, I could clearly hear the same sound again and the Power LED turned on for a second and then immediately turned off again. (Monitor completely off)

I never saw a monitor from inside so I took it apart, hoping it was just the fuse. There’s 3 PCBs and I took out the power supply after leaving it for a couple of hours to avoid getting shocked by a capacitor. The main fuse looks good to me and the caps show no bend. The only thing that I saw is a small burned spot besides the Neutral (see picture 2), which looks like a bad soldered spot to me. I’ll attach some pictures of the pcb. I don’t know a lot about electronic troubleshooting so I‘d appreciate any help I get. I really need this monitor to work from home.

I think most of BenQs power supply pcbs are the same, as all the schematics I found pretty much match up with my PCB
Monitor: BenQ RL2455HM B789CD53-6A6A-43FB-B0E8-2DCA4B2772C2.jpeg39A17184-18FE-4681-AD3D-1A522D7055E4.jpeg2130EC7C-DBE4-4A1E-8785-D401A36F4CA4.jpeg
 

wayneh

Joined Sep 9, 2010
17,152
If you look again I think you'll see that the PCB cracked along the back (inside) of the power receptacle, including underneath where the arcing occurred. In resoldering, make sure you bridge the gap caused by that mechanical crack. Using little pieces of wire wouldn't be a bad idea.

If you can get a little super glue to wick into the PCB, put a clamp on it for a while. That might help stiffen that area. Right now it's like broken bone and very vulnerable to further separation.
 

sagor

Joined Mar 10, 2019
439
The crack that shows up between the power inlet "N" and the "SG2" suggests that the trace in that area is broken and arced due to the crack breaking the trace. That is where you see a "burn mark". Try jumpering across that trace.
 

Thread Starter

aviioo

Joined Aug 27, 2020
8
If you look again I think you'll see that the PCB cracked along the back (inside) of the power receptacle, including underneath where the arcing occurred. In resoldering, make sure you bridge the gap caused by that mechanical crack. Using little pieces of wire wouldn't be a bad idea.

If you can get a little super glue to wick into the PCB, put a clamp on it for a while. That might help stiffen that area. Right now it's like broken bone and very vulnerable to further separation.
Thank you both so much! I actually didn’t realize it was cracked but I fixed it by soldering two small wire pieces in and it works like a charm. Really saved my week! :D
 

Thread Starter

aviioo

Joined Aug 27, 2020
8
The crack that shows up between the power inlet "N" and the "SG2" suggests that the trace in that area is broken and arced due to the crack breaking the trace. That is where you see a "burn mark". Try jumpering across that trace.
Thank you both so much! I actually didn’t realize it was cracked but I fixed it by soldering two small wire pieces in and it works like a charm. Really saved my week! :D
 
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