Dell U2312HM power supply board repair - Page 1
Forum section: electronics / repair

author: cap87
author_rank: Newbie
timestamp: May 09, 2020, 03:02:34 pm
content: My LCD monitor just failed and i figured this would be a great opportunity to learn about electronics in general. I'm going to try to give as much information as possible and feel free to ask me for any additional information.Symptoms:This is a Dell LCD (U2312HM) and it simply went out while it was running. Not even the power led turns on now.Tools:I have a really cheap multimeter and soldering iron. I'm willing to buy useful tools for this repair both for the learning experience and future problems i might encounter with other electronics.What i have tried:Checked the fuse for continuity and it seems fine. I wasn't sure where the fuse was since this looks a bit different from the fuses i've seen on repair videos but after a little googling i figured it out. It looks like this:Tried to check the capacitors with my multimeter but i'm not sure what to look for. They seem to be charging (i could not get a reading on 1 but i suspect it's because the pads/probes, had some difficulty measuring some of them)but i know that might not mean much if they are 'out of spec'. And can I even measure capacitors without desoldering them?I figured i asked here before trying anything else. I haven't powered on the board to measure anything as i'm not sure what is safe and what is not. I know that capacitors hold a charge and i used a wrench to discharge them (is this even the proper way to do this?).I'm not even sure if this power board is the problem, i don't see any obvious damage on either board and i figured this would be a good place to start diagnosing.The power board is an E58528 and it seems like there are replacement boards online for cheap (not in the same form factor so that is another issue), but i would like to replace it as a last resort.Here's a pic of the board:I'm about to order all the capacitors on this board since they are pretty cheap anyway.Would appreciate any help on what and how to check components or any pointers in the right direction.

author: tunk
author_rank: Super Contributor
timestamp: May 09, 2020, 03:19:01 pm
content: Is there any voltages on the output, i.e. to see if the PSU is dead?

author: cap87
author_rank: Newbie
timestamp: May 09, 2020, 04:36:32 pm
content: Quote from: tunk on May 09, 2020, 03:19:01 pmThanks for the tip, i should have thought of doing exactly that.I have just checked each wire on the cable that connects to the LCD main board and the voltage seems to more or less match the markings on the board.Pic:https://imgur.com/a/QboFYuCOn wires 3,4,5,6, 11 i see 5VOn wire 12 i see ~0.85VThe other small wire connects directly to the display and i'm guessing that's for the backlight? It also seems to have voltage on the millivolt range.Does this mean that the capacitors were not needed and maybe the problem is on the main board?

author: cap87
author_rank: Newbie
timestamp: May 09, 2020, 05:04:29 pm
content: Well this is awkward: I tried to connect everything together and it suddenly works againI'll try to use it for a while and see if anything changes

author: tunk
author_rank: Super Contributor
timestamp: May 09, 2020, 05:42:50 pm
content: Bad contact or solder joint?

author: cap87
author_rank: Newbie
timestamp: May 09, 2020, 07:01:50 pm
content: Quote from: tunk on May 09, 2020, 05:42:50 pmI guess it was a bad contact somewhere, i'll give an update if it dies again.