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9205(2)A multimeter

Discussion in 'Troubleshooting and Repair' started by john douglas, Oct 12, 2018.

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  1. john douglas

    john douglas

    3
    0
    Oct 11, 2018
    I have a multimeter Excel DT-9205(2) A. While measuring resistance in the circuit,the probe accidentally touched the positive voltage.Since then whenever I tried to switch on the multimeter , lcd display showed digit for a second and disappeared.On carefully examining the IC near the on/off switch is seemed to be burnt and the ic number is impossible to read .I will be very grateful if anybody can IMG_20180929_134222.jpg suggest the IC number and circuit diagram to repair my multimeter.Thanks in advance.
     
  2. 73's de Edd

    73's de Edd

    2,872
    1,216
    Aug 21, 2015
    Sir john douglas . . . .

    Related to damage from voltage misapplication a TL062 is most suspect.

    That units schematic shows two LM358 flat packs being used in the capacitor test function.
    A HARRIS version of a LM358 . . .17358 . . . is being used in a power supply function
    On your photo, one of the visible I.C.'s is showing a ST manufacturer, but the units critical identifier is being hidden by the right one, of the two GREEN poly capacitors, the visible info marking is probably being a code date, on the end, relating to the manufacturing date of that chip, suggesting, it possibly being the 35th week of 2005 or 2015.
    BUT . . . the closest IC to the power switch in the top corner is a TL062.with an associated C20 and D7 nearby.


    CLARIFIED SCHEMATIC . . . . . DT9205
    upload_2018-10-12_3-40-26.png

    73's de Edd
    .....
     
    Last edited: Oct 12, 2018
    Richard9025 likes this.
  3. Bluejets

    Bluejets

    4,062
    848
    Oct 5, 2014
    You do realise a new one is $15.00?
     
  4. hevans1944

    hevans1944 Hop - AC8NS

    4,474
    2,085
    Jun 21, 2012
    In Cambodia $15.00 may be equivalent to a month's earnings. And this multimeter may be difficult to purchase online without a long wait for delivery to the OP's country. However, I doubt it can be economically repaired unless the components required can be obtained for free. Best to replace it if possible and move on with your life.
     
  5. john douglas

    john douglas

    3
    0
    Oct 11, 2018
    Dear sir 73's de Edd
    The second ic is 324 a ST manufacturer near two green poly capacitor.Please I need the number of first ic near on /off switch (red encircled) which seems to be burnt out.Thanks sir IMG_20180929_134206.jpg IMG_20180929_132006sc.jpg
     
  6. john douglas

    john douglas

    3
    0
    Oct 11, 2018
    Dear sir as you suggested closest IC near to power switch is TL 062 , BUT http://www.ti.com/lit/ds/symlink/tl062.pdf shows TL062 has total 8 pins (4 on each side) whereas the ic burnt ( encircled red ) has total 14 pins (7 on each side). So I think it is different ic .Hoping the answer from you.
     
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