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Thread: 5154 line voltage change

  1. #1

    Default 5154 line voltage change


    I have a US 120v IBM 5154 Enhanced Color Display and Iím looking to convert it to 240v line voltage which we have here in UK. I bought the monitor on eBay and amazing it survived shipping and works for a few seconds on my low wattage step down transformer before that cuts out.

    I read that the line voltage can be chnaged by removing the jumper plug in socket M5 on the psu board.
    I have the schematic from the SAMS photofact and it shows M5 in the PSU line input path so seems feasible but Iím not good enough with analog electronics to determine if it is indeed to switch input voltage.

    Does anyone know if there is a simple way to convert the 5154 to 240 volts?



  2. #2


    If you post the schematic I can look at it for you.

  3. #3


    Yes, removing jumper M5 changes the bridge to full wave across the main smoothing caps C7, C8, suitable for 230VAC.But, also check the voltage ratings on all caps across the AC, or AC to ground before the bridge, specifically C5, C6 which are Y2 caps. C34, C35 are X2 caps. Replace if required with Y2 and/or X2 rated at 280VAC or such.C2, C3 are marked as 1kV on the schematic, check that they are.Check that C7 and C8 are rated as specified. Replace if bulged or leaking.Now for the degauss coil. The good news is that when I converted my 5153 from 120 to 230VAC I found that it worked perfectly as-is because the PTC had a high enough rating. Find PTC1 and check that the number on it is something like 280. Also you can reduce the fuse rating by half if you wish, to ensure equivalent protection.Obviously you will need to pay great attention in case any components get unexpectedly hot on first power-up. Be careful working around these parts with power on. Use an RCD on the power source.

  4. #4


    Hi Paul,

    Thanks very much for taking a look and providing this information. I thought it would be something like that but my knowledge stops at bridge rectifiers and I wasn't sure how the M5 link was affecting it.

    Will let you know how it goes!

  5. #5


    Happy New Year!

    I finally manage to find some time to open up the 5154 and take out the PSU. I've attached a few pictures.

    It seems to be in very good shape in general, the PCB only shows very mild signs of heat around the main power resistor and the smoothing caps are bulging - but have not leaked. (All the caps seem to be glued down, which I did initially mistake for leakage).

    One of the X2 caps is completely blown apart (I could hear it's remains rattling around the PSU as I dismantled it), luckily it seems pretty clean and hasn't damaged anything that I can see.

    So I have the caps required on order from RS and hopefully I'll be able to attempt the repair and 240v operation at the weekend.Good - Back of PCB.jpgGood - Blown X2 Cap.jpgGood - PSU overview.jpg


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