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Is it possible to fix old PC monitor

Discussion in 'Troubleshooting and Repair' started by pharaon, Feb 9, 2018.

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  1. pharaon

    pharaon

    239
    3
    Oct 28, 2014
    i want to know if it's possible to fix this old PC monitor

    [​IMG][/url]
    [​IMG][/url]

    [​IMG][/url]

    [​IMG][/url]
    [​IMG][/url]
    [​IMG][/url]
    [​IMG][/url]
     
    Last edited by a moderator: Jun 7, 2018
  2. Minder

    Minder

    2,917
    614
    Apr 24, 2015
    Looks like some open traces/connections around the HOT (Horizontal output Txfr)!
    Has someone been working on it?
    M.
     
  3. JWHassler

    JWHassler

    78
    16
    Dec 22, 2014
    There is an unsoldered(?) terminal in the seventh picture, neat the words "Rev 03"
     
  4. Minder

    Minder

    2,917
    614
    Apr 24, 2015
    Yeah, that is the ones i referred to;)
    M.
     
  5. pharaon

    pharaon

    239
    3
    Oct 28, 2014
    no i just open it, i didn't use it for couple of years since it broke
     
  6. pharaon

    pharaon

    239
    3
    Oct 28, 2014
    i know but want to make sure if it's the only problem is there anything else i need to check
     
  7. Minder

    Minder

    2,917
    614
    Apr 24, 2015
    Well I would re solder the open joints/traces first and see what transpires!
    M.
     
  8. kellys_eye

    kellys_eye

    4,279
    1,146
    Jun 25, 2010
    I'd power it up and try to explain any ACTUAL fault you have. A set of pictures tells us little/nothing. Is there an actual fault symptom - have you taken any voltage measurements around the board?

    The missing trace is an 'obvious' area for concern but, once repaired, may just lead to other problems - fix it and let us know the results.
     
  9. pharaon

    pharaon

    239
    3
    Oct 28, 2014
    the power led don't light

    [​IMG]

    i solider the loses parts, can i test it this way or do i need to reconnect the board to the monitor?
    and is there any cautions before testing it
     
  10. Minder

    Minder

    2,917
    614
    Apr 24, 2015
    Be careful where the end of the CRT HV lead is, for a small B&W monitor it will be around 9kv.
    You really need the crt to complete the picture.
    Specialized measuring device is required to measure the EHT voltage.
    Ensure the ground connection on the crt is connected to the board if testing it out of the case.
    M.
     
  11. pharaon

    pharaon

    239
    3
    Oct 28, 2014
    which one?
     
  12. Minder

    Minder

    2,917
    614
    Apr 24, 2015
    Apart from the scan coils around the neck of the tube and the cathode socket, there is a HV lead from the HV transformer in question to the connection in the side of the CRT (9kv), there should also be a lead(s) from the board common to the mounting of the CRT and the black (aquadag) coating on the outside of the tube.
    It is best to test with everything assembled.
    M.
     
  13. 73's de Edd

    73's de Edd

    2,775
    1,159
    Aug 21, 2015
    Why for . . . . .you no give us Brand and Model number . . .. .so that we can research what pin #1 of LOPT goes to ?
    In addition to D10.

    And I guesstimate ultor voltage at typically being ~ 1 KVDC per inch of kine screen size.
     
    Last edited: Feb 10, 2018
  14. pharaon

    pharaon

    239
    3
    Oct 28, 2014
    i done it i heard that sound of turning on those old monitor but it's dark and the power led is not on
    which part i should test

    [​IMG]
     
  15. pharaon

    pharaon

    239
    3
    Oct 28, 2014
    any idea what i should check next?
     
  16. 73's de Edd

    73's de Edd

    2,775
    1,159
    Aug 21, 2015

    Sir pharaon . . .


    UNISYS techno info ain't easily / readily available . . .especially when they source it out of Korea, from the back door of Hyundai.

    REFERENCING:

    Your very first photo, with the dominating large BLACK canned main filter capacitor for the AC line supply, being just left of top center.
    There is a folded around alum metal heat sink for the HEATSINKING of the POWER FET of the SMPS.
    Me thinks that I see a hole where the screw used in mounting it used to be.
    Was it someone else . . . . or you . . . . . that pulled that part ?
    I think that it might be labeled as Q801 on the board area near it.
    Also, is it being fed by a nearby 8 pin mini IC . . . .IC801 . . .with it being a KA3842 ?

    ABOVE . . .

    I'm just testing to see if I have a like Hyundai schematic . . . . and how many miles per gallon that it gets.

    73's de Edd
    .....
     
  17. kellys_eye

    kellys_eye

    4,279
    1,146
    Jun 25, 2010
    There is a separate SMPS section (identified by the clearance areas of 'no copper' on the underside of the board) that needs to be checked and - if required - repaired first.

    I suggest that the OP skill level set is minimal and that, even f the fault could be identified, sourcing and replacing parts would be difficult to say the least.

    If we can source the schematic there is a slim chance things could progress......
     
  18. pharaon

    pharaon

    239
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    Oct 28, 2014
    someone else
    Q103
    "what piece should i get for it"?

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
  19. pharaon

    pharaon

    239
    3
    Oct 28, 2014
    can you show me on the picture
     
  20. pharaon

    pharaon

    239
    3
    Oct 28, 2014
    any one know
    Q103
    "what piece should i get for it"?
     
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