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Varistor TVR 10241 blown

Discussion in 'Troubleshooting and Repair' started by aloke, Feb 11, 2020.

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  1. aloke


    Feb 11, 2020
    Hi, I connected power supply Meanwell LRS-350-24 into 220v outlet while it was in 110v mode. As a result, the Varistor TVR 10241 blew up. Can I just remove this and use the power supply in 220v mode? Do I absolutely have to replace the Varistor or can just remove it? I don't want to risk damage to the 3D printer motherboard and other components. IMG_20200211_231000.jpg IMG_20200211_232138.jpg
  2. 73's de Edd

    73's de Edd

    Aug 21, 2015
    Sir aloke . . . . .

    Your MEANWELL power supply is not going to serve you very well at all, if you keep treating it MEAN !
    Your exploded component was MEANT to engage only for a mere fraction of a second, in case of any incoming overvoltage peaks.
    Your time frame certainly exceeded all of its capabilities. NOW you need to check and see what OTHER conponents, likely were blown or overstressed, by your misdeed, starting with the AC line incoming power fuse and then any power rectifier diodes / FW blocks or incoming surge thermistor, all the way to associated electrolytic caps.
    All BEFORE you attempt to power up again.

    73's de Edd . . . . .

    I just now commented to my wife that she was getting fat . . . .she observed, thought it over a bit and then fully rebuked me with . . . . .
    " NO !. I'm just getting easier to see. "

  3. aloke


    Feb 11, 2020
    Thank you for your reply. The fuse also blew up along with the Varistor. This also tripped the circuit breaker on main electric board. Everything else on the board looks fine. I switched voltage to 220v. I replaced the fuse already. Will the pkwer supply work if I just remove the Varistor from PCB?
  4. Bluejets


    Oct 5, 2014
    Although a good scan is a starter to fault finding, it is a good move to meter out certain items as 73'sde Edd outlined.
    Electronic faults are more often than not, not visible by eye.
    More than likely it would have taken out the main switcher or ic associated with it.
  5. 73's de Edd

    73's de Edd

    Aug 21, 2015
    Sir aloke . . . .

    Check out the AC line input , power supply components as best as is possible and then sub in a 60 watt at 120V or 220V incandescant lamp ( in accordance to what your line voltage is) , for that blown AC line fuse.
    Then on power up . . . with that lamp being in series with power input, will tell you if you are having excess or catastrophic power pull on that subsequent, exploratory power up.
    An initial brilliant light up is being indicative of STILL serious over power consumption, while a slight glow or glow and then dimming down is sign of a normal initial charge up of the main filter capacitors.
    But . . . .there THEN won't be adequate power passage thru that series lamp, such as to permit full and normal operation of the power supply.
    BUT you can then, at the least, check for the reduced degree of voltages on the initial RAW DC supply(ies).
    Then you can chance a gamble of a short and quick power up with the regular fuse installed, in place of the prior current limiting test lamp.

    Will the power supply work if I just remove the Varistor from PCB?

    Yes, it is just shunting transient excess voltage across itself . . . . . BEST to replace it, to retain that protection in the future . . . . .but it is not initially required, in order to make an evaluative power supply test.
    You can SEE the tremendoud power it dissipated, from reaching deeper into your unit, while it was still functioning / alive.
    I would now somehow expect that it is probably just going be an arcing or glowing hunk of carbonized mass, if left in circuit on the board.

    Thaaaaaaaassit . . . .

    73's de Edd . . . . .

    Just because I have a short attention span, doesn't mean that I . . . . . . . . . . . . . . . . . . .

    Last edited: Feb 12, 2020
  6. 73's de Edd

    73's de Edd

    Aug 21, 2015

    MEANWELL LRS-350-24

    Looks like your potentially most problematic / failed components just might be the . . .

    RED flagged AC line fuse, which is
    passing AC power across the
    LILAC colored X safety capacitor, out to the two
    Copper magnet wire contra -phase-wound / peak voltage cancelling RFI-EMI filter chokes
    which pass AC power across the GREY colored X safety capacitor
    A sprinkling of BLUE cased Y safety capacitors to ground are nearby.
    Then AC goes into the BLUE flagged FWB diode block and then sends raw DC out
    thru two GREEN flagged low resistance, input surge NTC thermistors
    Your familiar pair of PINK flagged peak voltage Varistors ( Yours are YELLOW . . . . these are ORANGE cased )
    and finally the pair of WHITE flagged raw DC voltage electrolytic storage capacitors.
    Then the passage of their resultant raw DC up to the large white power transformer's primary and the associated
    power switching FET (s), . . . less their heat sink . . . . located at the very top side of the power transformer .
    The FLAGGED parts, are the most potentially suspect in your SPECIAL, self destruction situation / predicament.

    Thaaaaaaaaaaaaassit . . . .

    73's de Edd . . . . .

    Last edited: Feb 12, 2020
  7. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    ... but don't forget to insert a new varistor once your initial tests have shown the rest of the circuit is fine. Otherwise the next hickup on your mains voltage can easily destroy the rest of the circuit.
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