Replace your LCD power supply


[Computer Guru]‘s LCD power supply went out, making it a useless pile of plastic. He used an old computer PSU to replace the defective one. After he identified the outputs on the built-in supply (The one’s I’ve pulled apart were labelled) he stripped down the replacement PSU to provide the necessary voltages.

Comments

  1. Matthew says:

    I love how Hack A Day is on the screen. Priceless.

  2. Wolf says:

    After reading the summary, I thought he had somehow hacked the power supply to produce different voltages (which would be crazy-usefull btw).

    Simple and practical either in any case.

  3. Dennis Ferron says:

    @wolf: You can do that – change the voltages on a computer power supply. I have a computer power supply I turned into a workbench powersupply adjustable from 2.5 to 16 volts. It’s a fairly simple matter of changing the voltage divider on the sense input to the regulator IC. Unfortunately you can only change the voltage on one line; the other lines will all move up or down in voltage in proportion. The ratios of the voltages to one another are determined by the windings in the power supply’s transformer, and only one output is actually regulated; the rest just follow it.

  4. subxero says:

    It would be possible to power multiple LCD monitors from a single, decent-wattage (250-450W) supply without any problems, I’m assuming. This sounds like an interesting solution to my multiple-monitor setup. Sweet idea.

  5. Bhima says:

    If I was in such a situation, I’d be a lot more interested in using an ultra efficient power supply rather than a ‘free’ power supply. However, I confess this is a new obsession of mine and I have only recently replaced all of the power supplies I use to > 93% efficient units. The way I figure it, the power supply is one of the most important links in the efficiency chain. The significant drop in fan noise is also a benefit.

  6. aztraph says:

    had a friends monitor power supply burn up in a fire, easy enough, tap into the 12 volt from one of the drive plugs and drill a hole in a blanking plate to accept a plug, then a matching plug from her old monitor power supply(best if you use all the same size plug, so it doesn’t matter which way the cord goes) this is assuming the monitor is a DC monitor. It is still in use and has the added advantage of coming on with the computer. I’ve built a second one but didn’t need it, i’ll take a few pics and submit them but never considered this a hack, just a necessity at the time.

  7. computerwiz_222 says:

    I picked up a 17 inch monitor with a blown inverter board about a year ago… I replaced the inverter with one of those CFL kits for cars. I simply connected the monitor CFLs to the inverter output and then tied into a switched power on the PSU. The thing works great and the only thing I lost was brightness control.

    It is a great garage monitor

  8. HeBD says:

    yeah i got an lcd screen here with a bad power supply and cant get the part i need to fix it.
    to bad the powerboard also puts out 470Vac for the back lights :s might have to get some leds…
    nice hack. i think i’ll just use the psu in my pc though… PSUs used to power the monitor back in the day so no reason not to do it again.

  9. Emon says:

    Personally, I would have modded my PC to have a 12, 5 or whatever necessary outputs on the back (like in an empty expansion slot bay, I would add a socket) and then run the LCD off of my PC. It would make the setup more portable, too, of course it would need to be with THAT PC. Either that or you’d have to supply an appropriate power brick.

  10. Very nice, and free solution. Even if it is as ugly as hell, it’s still free! :D

  11. andrew says:

    for those suggesting powering an lcd monitor from a pc: most of the time you *won’t* be able to do that. unless the psu in the pc is ridiculously powerful, the combination of pc + monitor is likely to pull way more current than the psu can handle.

  12. cde says:

    Andrew, given that mosts lcds are powered by 12v 3A~4A max at the inverter/power brick, and thats a buffed up number, a pc with a decent powersupply should be able to do it. One of my thin client says it needs a 12 5a ps, but I can run it off 3a with no problem.

  13. Chupa says:

    @andrew

    my old power brick for a viewsonic 17″ says 1.3A@12v. Looking at the box for the current PSU in my computer its able to supply 36A@12v. Most people will be fine.

  14. Morten Agnor says:

    I think the problem with powering the LCD from the computer PSU would be that normally equipment draw extra ampere at the moment you turn it on. This could be fixed with a little cicuit board with a delay, a simple capacitor and a relay.

  15. O Mattos says:

    I power my 12 volt 19 inch lcd screen from one of the 12 volt rails from my PC power supply (the supply is in the PC – I tap off 12 volts from one of the hdd connectors, like suggested above). I thought it would overload the psu or put too much electrical noise into it, but everything seems to work fine even under load.

  16. O Mattos says:

    no. 12: That may be the case, yes, but also most power supplies have big capacitors to deal with short spikes in power use way above their rated power output. Those same capacitors are what keeps some PC’s going for a few secs when you unplug them. (other PC’s don’t seem to do that which is a bit odd, I guess they must power off the supply as soon as the AC input is lost/bad as a protection)

  17. aztraph says:

    anyone wanting to debate the workability of my suggested, “tapping off the PC’s power supply” a little more background info about the monitor, the original power supply was 12vdc and 1 amp max output, at these levels i think anyone could see that this particular solution was viable for this particular problem, but as in hacking anything, all situations are different, we all know this so lets look for all the different problems, and come up with as many solutions as possible. lets make a new category.

  18. strider_mt2k says:

    For just plain keeping stuff running I think it’s great!

    As for running your monitor from your pc’s power supply while the pc is using it, well that’s a great way to find out why they aren’t doing that already.

  19. Doug says:

    Far out. Man; that is what having a DIY frame of mind is all about.

  20. jaded says:

    Nice timing. The power supply just went out on my old Viewsonic last week, so tonight I replaced it with a new 24″ Samsung. Good thing my wife doesn’t read hack a day.

    At least now I won’t throw away the old one.

  21. Alex says:

    Wow, I had the same exact problem with that same exact monitor. And used the same exact solution! Crazy how hack-a-day readers think alike. Although, I didn’t think to submit my repair to hackaday :-)

  22. Nuno says:

    A few months ago I got a non-working LCD monitor from the trash and without a power supply. I decided to fix it and in the process also built a switched-mode power supply for it, using a simple LM2576-ADJ NSC buck converter I.C.. In my case I needed 20V@2.3A. You can find it both on my webpage, but the power supply circuit is so simple that you can actually go directly to the National Semiconductor website or any other chip company and use one of their chips for SMPS, if you feel up to it…

  23. ben s says:

    for those claiming that they ran old CRTs off of their PC PSUs, you’re a bit off. What you were actually doing was plugging them into an AC passthrough connector on the PSU that effectively made the monitor and PSU share the same power cord to the wall outlet and nothing else.

  24. jaded says:

    Oh, well. It wasn’t the power supply (not that I bothered testing it first.) Does anyone in the Twin Cities area want a non-working Viewsonic 19″ VX900 with a slightly chopped up power harness? :-)

    If not, it’s headed for the recyclery next trip I make.

  25. Charles Stoodley says:

    I have just purchased a Dell 17″ LCD monitor by auction to replace my space consuming CRT but found that there was no power supply with it. It requires a 14VDC 3A output which is common enough, but, being a Dell model 1702FP monitor, the socket appears to be an unusual size. Can anybody help me with any suggestions?

  26. Walrus23 says:

    I have an Acer 15” LCD monitor that takes a 12v DC (2.7A) input on the back, however i don’t have a power supply. i was thinking fo running my LCD from an old PC psu, but then i remeber trying to do the same with a network switch that needed 12v 1A DC and it started smoking when i turned on my PC. I had two weeks waiting for my mate to return my spare, swapping floppies between my pcs in the meantime. it turns out that the pc had a 26A output, 26 times more than the router needed, and itr was too much current. how can I be sure that isn’t going to happen with my LCD? if it won’t hurt it, i’ll be happy to connect it, otherwise ima keep looking for a psu for it. :) looking forward to reading your replies.

  27. Steven says:

    I did this with my LCD it had a 3 year warranty but ended a month ago and the power supply went bad so did this and it works fine. brilliant idea!

  28. Wash says:

    Question,my Go-Video 22″ start only pressing the start button ,not the remote,sometimes I have to press it 5 times sometimes 40 times,I did check the power supply and output is fine,any ideas?

  29. This monitor is not feature rich, but it is affordable, has good quality and has the “back to basics” appeal. If you are a hold out with the old CRT and didn’t want to spend much money on an LCD, this would be a perfectly fine option.

  30. Ed Pagan says:

    Could you tell me how I could used a psu to repair my Dell se198wfp lcd monitor

  31. Shadout says:

    I have a problem, it looks like my inverter is connected to lcd’s psu.. Is there any way to solve that??

  32. duy nguyen says:

    i tried to hack mine display but it showed upp that it doesnt look like the circuitboard above…., the back light circuit is not separatte as the lcd on the picture…., i have really destroyed my display -.-

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