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Led volt & amp meter broke capacitor

Discussion in 'LEDs and Optoelectronics' started by mrel, Sep 15, 2017.

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  1. mrel

    mrel

    103
    0
    Jul 2, 2008
    Hello
    Have a led volt&amp meter model yb27va (C1) the capacitor broke crack any one have this same model meter ,do you know value of that capacitor?
    The capacitor ( C1 ) is located left of wire connector black and red wire.
    mrel IMG_20170915_030414.jpg IMG_20170915_030414.jpg
     

    Attached Files:

  2. kellys_eye

    kellys_eye

    4,275
    1,147
    Jun 25, 2010
    What markings are on the capacitor?
     
  3. dorke

    dorke

    2,342
    665
    Jun 20, 2015
    Well,

    Please take a good quality picture of the cap. and the SMD part near it.
    It is a tantalum capacitor(probably at the output of the SMD LDO) which we can identify from what is written on it.

    I suspect it isn't the only burnt part.
     
  4. kellys_eye

    kellys_eye

    4,275
    1,147
    Jun 25, 2010
    Suggestive of reverse power connection.....
     
  5. 73's de Edd

    73's de Edd

    3,081
    1,301
    Aug 21, 2015
    Sir mrel . . . . . . .

    My also emphasizing . . . .
    Suggestive of reverse power connection.....
    Or a wall wart power supply being connected into the unit which could, if not closely inspected, easily result in incorrect polarity application OR :eek: raw AC voltage being fed into the unit

    Referring to the meters data below, looks like 30 VDC is the maximum power supply voltage and that is coming in on the RED and BLACK pair of wires.
    I would expect that RED wire, of the two, to be directly connected to the banded + lead of that smoked tantalum electrolytic capacitor.
    BTW what supply voltage level were you using on the unit.

    TROUBLESHOOTING:

    Have NO power connected up and unplug that 2 pin power connector and test from the RED wires pin on the PCB, over to the + of that electrolytic to confirm a direct connection.
    Also check across the electrolytic to confirm if it might have transitoned to a short, or else I suspicion that it just fractured into a split and opened up connection completely.
    Looks like they might have just incorporated a common power zener diode to pre-regulate from a max of 30Vdc input on down to 5V which could tale care of the unts LED display aspects and then the 78U33 just above the blown capacitor regulates on down to 3.3 for the electronics brains aspects.
    Center lead as well as the top heat sink tab is being ground on that 78U33 unit, with DC input being the lead closest to the bad cap as the DC input, and with the very top lead being the regulated 3.3 VDC output.
    You might ohm across from ground to both leads to see if no dead shorts exist.

    If my unit to evaluate, I would be pulling that bad electrolytic free from its pads and then installing a conventional 22 ufd @ 35 VDC rating with shortened leads and L bends at each leads end to pre tin and then reflow solder onto the old units pads . . .with polarity being DOUBLE confrmed.
    AND if you happened to have been using a 9V battery for power I would have my eyes glued onto on the LED display . . . and then make battery contact . . . . for no more than tenths of a second of a second to see if the display responded with a reading.
    If so, then a full battery up and test the voltage input with an applied voltage.
    If lucky then, that cap was the only loss. and I would just stick with my replacement type.
    In those dry types of tant caps . . . above 35VDC costs a premium as well as capacitance above 22 ufd.

    PRODUCT REFERENCING:

    http://www.wonmeter.com/yb27va-2in1...dc-4530v-power-supply-p-403.html#.Wbwt_7KGOUk

    73's de Edd
     
    Last edited by a moderator: Sep 16, 2017
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