Testing TV PSUs with dummy loads?

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • Beowulf
    Senior Member
    • Dec 2012
    • 175
    • USA

    #1

    Testing TV PSUs with dummy loads?

    Hi guys,

    I need your opinion on how to test TV power supplies by themselves. I've seen a couple of techniques but I'm unsure of their accuracy.

    So, for example the one method I've been trying to implement is with the use of dummy loads (#1157 car tail lights), but I'm not getting the expected results even when trying with known good power supplies.

    The problems I'm having is that I see a voltage drop (from 12v down to 9v, for example) when I use the loads and also using the high filament wont work (light doesn't turn on).

    I'm currently using a 100 ohm resistor (have to stop at radioshack to get a 1k and see if it makes a difference).

    Regards,
  • retiredcaps
    Badcaps Legend
    • Apr 2010
    • 9271

    #2
    Re: Testing TV PSUs with dummy loads?

    See budm's album

    http://s807.photobucket.com/user/bud...?sort=3&page=1
    --- begin sig file ---

    If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

    We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

    Please do not post inline and offsite as they slow down the loading of pages.

    --- end sig file ---

    Comment

    • Beowulf
      Senior Member
      • Dec 2012
      • 175
      • USA

      #3
      Re: Testing TV PSUs with dummy loads?

      Hi, thanks.
      Yeah that's what I was looking at when I first tried it.

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #4
        Re: Testing TV PSUs with dummy loads?

        For 24V testing, you can use 12 Ohms 50 Watts minimum resistor which will draw 2A from the power supply.
        For 12V 1A current draw, the resistor will be 12 Ohms, 12 Watts minimum. So if you can get two 12 Ohms 50 Watts resistors for testing, that will be fine.
        When testing the power supply, you need to look at the output current specification to find out how much it can put out, since the cold resistance of the lamp will be 10 times less than what it draws after it lights up. So you should check the cold resistance of the lamps you are using first. Some power supply can handle the current surge, but some will go into shutdown when it sees to much inrush current.
        Never stop learning
        Basic LCD TV and Monitor troubleshooting guides.
        http://www.badcaps.net/forum/showthr...956#post305956

        Voltage Regulator (LDO) testing:
        http://www.badcaps.net/forum/showthr...999#post300999

        Inverter testing using old CFL:
        http://www.badcaps.net/forum/showthr...er+testing+cfl

        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
        http://s807.photobucket.com/user/budm/library/

        TV Factory reset codes listing:
        http://www.badcaps.net/forum/showthread.php?t=24809

        Comment

        • JonathanAnon
          Badcaps Veteran
          • Jul 2012
          • 457
          • Ireland

          #5
          Re: Testing TV PSUs with dummy loads?

          I have 60W / 24V bulbs that I can get from my electrical wholesalers here in Portlaoise, Ireland. Very handy for testing laptop chargers with 2.5A load. You could then use the high wattage series resistor to adjust down the current.

          Some power supply can handle the current surge, but some will go into shutdown when it sees to much inrush current.
          Would an input thermistor from the primary section of an old SMPS, installed in series with the resistor and bulb, cure this problem..

          Comment

          • budm
            Badcaps Legend
            • Feb 2010
            • 40746
            • USA

            #6
            Re: Testing TV PSUs with dummy loads?

            Yes, you can use the Negative Temperature Coefficient (NTC) Thermistors, I.E. 4 Ohms NTC when it is cold, once the current start flowing then its resistance will go down. Just put it in series with the lamp.
            http://www.ametherm.com/inrush-curre...rrent-faq.html
            Never stop learning
            Basic LCD TV and Monitor troubleshooting guides.
            http://www.badcaps.net/forum/showthr...956#post305956

            Voltage Regulator (LDO) testing:
            http://www.badcaps.net/forum/showthr...999#post300999

            Inverter testing using old CFL:
            http://www.badcaps.net/forum/showthr...er+testing+cfl

            Tear down pictures : Hit the ">" Show Albums and stories" on the left side
            http://s807.photobucket.com/user/budm/library/

            TV Factory reset codes listing:
            http://www.badcaps.net/forum/showthread.php?t=24809

            Comment

            • Beowulf
              Senior Member
              • Dec 2012
              • 175
              • USA

              #7
              Re: Testing TV PSUs with dummy loads?

              That's good info, thanks. I'll try some of that.

              Comment

              Related Topics

              Collapse

              • AJ847.63e
                Testing ATX PSUs under load - Does loading the ATX 24 pin also load EPS & PCIE?
                by AJ847.63e
                Hi Folks,

                Just wanted to clear up a misunderstanding of mine (or what I expect is one). Isn't the 12V rail from the 24 pin, EPS and PCIE separated? IE if I put a power resistor on the ATX 12V pin that is not going to load, thus tell me if the EPS or PCIE rails are fine?

                I was recently watching ArIs from Hardware Busters video on how to properly test ATX PSUs without using 5 figure Croma substations.

                The PCB adapter he used breaks out the 12, 5 and 3.3V pins from the 24 pin and gives you banana plugs to connect to. That is a bit useless is it not? Aren't...
                05-06-2025, 10:37 PM
              • Nevillet
                Dummy loads for amplifier fault finding
                by Nevillet
                Hi All,

                I'm looking at upgrading my load resistors for power amplifier diagnostics and have a few questions:

                1. is it possible to use e.g. a kettle element as a load?

                and at the other end of the financial spectrum..

                2. Electronic loads - would they work?

                3. What's the gold standard method?

                Many thanks.
                05-25-2022, 12:42 PM
              • bauto601
                KDM 480W PSU upgrade succes! (opinions?)
                by bauto601
                Back in 2020 i bought a (2nd hand) compact ATX psu to replace my current one. My PC case only fits very short ATX power supplies so i didn't really have the choice of buying a decent 80Plus unit. The current unit is a modded YoungYear unit that i made a thread about a while ago:
                A "nice" YoungYear unit? - Badcaps

                The "new" unit is a KDM-M6480 480W psu, the 480W number is a typical KDM bullshit claim of course, but the 24A rating on the 12V rail seemed reasonable and the "Active PFC" claim gave me a bit of hope that this was going to be decent-ish....
                12-26-2023, 03:05 PM
              • iMic
                Vintage AT Power Supplies - Selecting Capacitors
                by iMic
                Hi,

                Back after a long hiatus with some old power supplies that need repairing. I've recently picked up a couple of 386SX systems, two 486DX systems, a SiliconGraphics Indy and an iMac G3 that either have verified leaking capacitors in their power supplies, or are likely to in the near future. For the sake of simplicity, instead of tackling all at once, I'm starting with the 386's and one of the 486's.


                The 386's power supplies are Seasonic SS4040A's, with caps that are visibly leaking, and 9 replacement caps per unit are required. Most appear to be from the Rubycon...
                02-19-2023, 06:45 PM
              • tony359
                electronic load for PSU testing
                by tony359
                Hi all,

                I've always tested power supplies using high power resistors but that can be time consuming (need to put together an appropriate resistance value and make sure you're not overloading etc).

                I stumbled into many electronic loads on aliexpress today. The below is just an example:

                Aliexpress link

                They're meant for batteries, would they work ok with power supplies? It would just be much easier to dial a trimmer than digging into a box of resistors (which then need to be connected etc).

                For sound gear testing I'll stick...
                02-05-2023, 09:08 AM
              • Loading...
              • No more items.
              Working...