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Enermax Platimax EPM1500EGT random turn on

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    Enermax Platimax EPM1500EGT random turn on

    Hi,

    I'm novice in smps repairs and lurker here also in addition to my preparation I have read Jestine Yong's Troubleshooting & Repairing Switch Mode Power Supplies many times and I cautiously proceeded in small steps a time.

    What's on the table?

    Enermax Platimax 1500W (EPM1500EGT)

    Symptom

    A fault is a little tricky here. When plugged into the wall for a first time (i.e. after proper discharge) PSU starts on power button (PS_ON) as expected, runs smoothly with all the voltages in tolerance also shows quite stable operation in ~600W load in OCCT, no freezing nothing – normal behavior.
    When I turn off the PC and try to power it on again, I can hear almost inaudible (with head close to the PSU) click sound and nothing happens further – no fan spin on PSU, no PWR_GOOD – no post.
    (1min video of the issue https://youtu.be/smy-17Tsxq4)
    To be able to turn it on again I have to unplug it from the line, then wait for discharge of the main capacitors and what's more interesting even after that I got 50:50 success rate of power on sometimes less and it gets worse with trials. When I leave the PSU unplugged from the wall long enough then I can turn it on without hesitation. Same behavior on another motherboard, cpu & ram.
    What is even more confusing is that if I'm able to resend the PS_ON from the second motherboard (power button combo long press-wait-press) then I can “ask” the PSU to turn on as many times as I want (without unplugging the PSU from the wall/discharging), then after 2-3 fail attempts with the “click sound” PSU starts on the 4th. At this point I can say it starts random. When unplugged long enough… Here you go - PSU starts on the first try.

    My Philosophy behind the issue

    As far as I know that issue is pretty common in Platimax series. This guy's issue with 1350W unit on YT looks identical to mine.
    Part1: https://www.youtube.com/watch?v=TaF14MQ7YO0
    Part2: www.youtube.com/watch?v=PqYSE1m1MXY
    Interesting comment in the Part2 from user rrbeats2004
    „i have two broken like this...its something with the voltage maybe“
    Which leads me to believe the issue is common and maybe even design flaw.

    What I checked so far?

    Ad1.
    Capacity & ESR of all key electrolytic & film caps apart from three caps with solid electrolyte on each 5V and 3V secondary PCB output due to bad accessibility (should be ok).
    Measurements here: https://1drv.ms/x/s!Am-Hq0zLeB5Egd4J...fc1NQ?e=MHVCgg
    Found out differential EMI X1 PET on primary out of declared tolerance, so I replaced it for high quality KEMET X1 PP 826nF. But no difference. Issue remains the same.
    Both primary thermistors and varistor measured ok.

    Ad2.
    Measurements of voltage cycle on the main capacitators after plug (turned off) – turn on (APFC running) – turn off (SUCCESFUL power on):
    https://1drv.ms/x/s!Am-Hq0zLeB5Egd8v...PHmWQ?e=bfXkNd

    Measurements of voltage cycle on the main capacitators after turn on again (FAILURE power on – “click sound”)
    https://1drv.ms/x/s!Am-Hq0zLeB5Egd8t...sRgCA?e=afTqzc

    PSU starts up normally when main caps are charged from APFC to <360V, but power FAIL occurs when charged to slightly above >360V (OVP at primary I guess?)
    So I assumed there is some kind of OVP or OCP activation on the primary side. With that in mind I focused on PFC controller ICE2PCS01 featured with these protections and which reside on primary side. Measurement done on pins VCC, VSENSE, GATE here
    VCC: https://1drv.ms/x/s!Am-Hq0zLeB5Egd8s...5fZVg?e=BhkGZT
    VSENSE: https://1drv.ms/x/s!Am-Hq0zLeB5Egd8u...LHKZA?e=Rv3ua8
    GATE: https://1drv.ms/x/s!Am-Hq0zLeB5Egd8w...bHwRw?e=lnJuYe
    When I measured on voltage comparator which assists in OVP and UVP protection LM393 on primary side right next to PFC controller on the same vertical board I found out that the VCC was about ~14V and OUTB (only one comparator is used) was HIGH only when power on successfully. When powered up unsuccessfully “click sound” same voltage for VCC for a split of the second and LOW OUTB.
    BOTH controller PFC ICE2PCS01 and OVP&UVP comparator LM393 when powered on unsuccessfully have VCC and outputs for a split second, then all disappear. Power on OK – voltages remains and are stable.

    Ad3.
    The “click sound”
    I thought that the barely audible click sound during FAILURE power on is relay, but when I soldered wire to its control coil I found out, that there is no voltage. And again, when PSU starts OK there is about 10V stable on the relay's control coil as long as it runs and is powered on.

    Ad4.
    When I measure on PGI pin of PS238 monitor on the secondary side during FAILURE power on there is no voltage during the click sound/power FAIL. If my assumption is right the relay does not switch so there is no primary voltage on the diode and resistor to the PGI pin which indicates no voltage to the secondary side – no switching start. And as always when PSU is powered up on PGI pin is about 1.37V stable.



    To be honest I am kind lost. Sorry for such a long story but I want to capture all my findings and provide you a whole picture of the issue.
    I leave you with the measured voltages on the secondary side when PSU is very light loaded, same applies to the 600W load
    https://1drv.ms/x/s!Am-Hq0zLeB5Egd8o...tx_rg?e=dbItYT



    Any help will be greatly appreciated.




    Misc:
    Local previous topic about Enermax Platimax:
    https://www.badcaps.net/forum/showth...light=platimax
    Review with detailed pictures:
    https://www.techpowerup.com/review/e...1500egt/4.html

    Datasheets:
    Attached Files

    #2
    Re: Enermax Platimax EPM1500EGT random turn on

    Solved. Replaced smd resistor CLOSED

    Comment


      #3
      Re: Enermax Platimax EPM1500EGT random turn on

      Hi,

      I think I'm having the same problem as you.
      Could you provide some more information about how you managed to fix this problem?
      Which resistor did you replace? How did you figure this out?

      Thanks!

      Comment


        #4
        Re: Enermax Platimax EPM1500EGT random turn on

        Originally posted by LeKowalsky View Post
        Solved. Replaced smd resistor CLOSED
        Hello! I`m having troubles with not turning on and klicking sounds with the Enermax PSU. Can you please share info, what resistor did You replaced?
        Thank You!

        Comment


          #5
          Re: Enermax Platimax EPM1500EGT random turn on

          Please, share what resistor replaced.

          Comment

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