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paulfxh
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Last Activity: 03-17-2016, 02:42 AM
Joined: 11-04-2015
Location: Limerick
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  • paulfxh
    replied to Acer LCD monitor on-off repeatedly
    in Troubleshooting Computer Displays
    Re: Acer LCD monitor on-off repeatedly



    Well, after six weeks the ILPI-139 power board finally arrived all the way from China and it works perfectly.
    So, I now have a fully operational 21.5" monitor for a total repair cost of €13 and some cents (a little over US$14).
    The board was purchased as a used board but it arrived in perfect condition other than being a little dusty.
    [URL="http://www.aliexpress.com/item/Free-Shipping-V223HQ-X223HQ-AL2016W-AL2216W-Power-Board-ILPI-139/32355792752.html"]Here[/URL]'s where I got it....
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  • paulfxh
    replied to Acer LCD monitor on-off repeatedly
    in Troubleshooting Computer Displays
    Re: Acer LCD monitor on-off repeatedly


    Well, the rectifier certainly looks OK but the fact that it exudes a strong smell of burnt plastic doesn't suggest it escaped unscathed from this incident.
    In any event, I've ordered a new power supply board for a very reasonable €13 so I'll just wait for that.
    Just hope that the main board and the screen which were attached to the power board were not damaged.
    I'll know soon. ...
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  • paulfxh
    replied to Acer LCD monitor on-off repeatedly
    in Troubleshooting Computer Displays
    Re: Acer LCD monitor on-off repeatedly


    Thanks for the suggestion.
    Well, I tried that on D804 but due to a last minute twitch of the hand I seem to have shorted out the diode with a resultant
    Not quite that dramatic but enough to render the board inoperable.
    So, whether the rectifier diode was deficient before or not, it certainly is now.
    Nevertheless, for a little more than the cost of a replacement diode, I can get a new power supply board.
    So, that's my next step.
    I want to thank everybody who contributed to this thread from which...
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  • paulfxh
    replied to Acer LCD monitor on-off repeatedly
    in Troubleshooting Computer Displays
    Re: Acer LCD monitor on-off repeatedly


    Hi momaka
    Many thanks for that great reply.
    It's a tutorial in itself.

    Just to avoid misunderstandings, when one of the F802 pins was desoldered from the board and the power board then connected to the main board and mains power, the power reading at the F802 fuse remained unvarying at 5.22 volts for about 10 minutes which is as long as I left it running.
    The screen backlights, however, did not light up as (I think) was expected.

    OK, I carried out all of the resoldering as suggested....
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  • paulfxh
    replied to Acer LCD monitor on-off repeatedly
    in Troubleshooting Computer Displays
    Re: Acer LCD monitor on-off repeatedly


    Thanks.
    OK, I removed the end of the fuse as you suggested (photographic "evidence" available but I was unable to attach it as keep getting "server error" message ) and hooked up the power board to the screen backlights and the main board and plugged in the mains power supply.
    The voltage on both sides of the fuse F802 was rock steady at 5.22v over a long period.
    However, as I assume you expected, the voltages at pins 1 and 2 of the 8-Pin connector between the boards were barely measurable...
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  • paulfxh
    replied to Acer LCD monitor on-off repeatedly
    in Troubleshooting Computer Displays
    Re: Acer LCD monitor on-off repeatedly


    OK, I tried this but am unsure which pins are S1, S2 etc.
    I see the pin denotation in the pdf but only the corner pins are marked on the actual board (1,4,5 and 8).
    For both units (U501 and U502), I will assume that Pin 1 is S1.

    Then for U501 I get the following resistance readings:
    S1-D1 1,755 Ohms (1.755 kOhms)
    S2-D2 1,754 Ohms (1.754 kOhms)

    For U502, I get
    S1-D1 1,750 Ohms (1.750 kOhms)
    S2-D2 1,750 Ohms (1.750 kOhms)

    These tests were done with...
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  • paulfxh
    replied to Acer LCD monitor on-off repeatedly
    in Troubleshooting Computer Displays
    Re: Acer LCD monitor on-off repeatedly



    OK, disconnected the Main Board and measured again the voltage on pins 1, 2, 4 and 5 with the black probe on Pin 3.
    All pins gave absolutely steady readings.
    Pin 1: VCC5V: 5.18v
    Pin 2: VCC5V: 5.17v
    Pin 4: GND: 0.00v
    Pin 5: On-Off: 0.00v

    The part numbers on the MOSFETs you mentioned are:
    U501: 9971GD 938466
    U502: 9971GD 938466
    I've attached close-up photos of each if you want to check.

    Where I am, we don't have GFCI outlets. However, the outlets are surge...
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    Last edited by paulfxh; 12-10-2015, 03:51 PM.

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  • paulfxh
    replied to Acer LCD monitor on-off repeatedly
    in Troubleshooting Computer Displays
    Re: Acer LCD monitor on-off repeatedly


    Many thanks once again for your comments and suggestions.
    I really am learning an awful lot from this thread.
    I tried your hairdryer suggestion and a number of interesting observations came out of this.

    1. First I should mention that my multimeter is not a top-of-the-range model. It's a Veyron VL-890D as shown in the attachment. Also, the manual provided is only in Chinese, which I cannot read, and I was unable to locate an English manual online.

    2. The "zero-reading" on this multimeter...
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  • paulfxh
    replied to Acer LCD monitor on-off repeatedly
    in Troubleshooting Computer Displays
    Re: Acer LCD monitor on-off repeatedly


    Thank you for that clarification.
    Yes, for the readings in my last post I used an external (outside of either of the monitor pc boards) ground for the black probe on my multimeter.
    I've repeated this exercise and this time I used Pin-3 (GND) on the 8-Pin connector (main board side) between the two boards for the multimeter black probe.
    Once again, I took the readings both when the blue power light was on and when it was off.

    Pin 1: VCC5v: Blue on 4.86v, Blue off 1.4v
    Pin 2: VCC5v: Blue on 4.86v, Blue...
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    Last edited by paulfxh; 12-09-2015, 05:14 PM. Reason: Additional item

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  • paulfxh
    replied to Acer LCD monitor on-off repeatedly
    in Troubleshooting Computer Displays
    Re: Acer LCD monitor on-off repeatedly


    Hi budm
    Thanks for the clear explanation.
    I've made the measurements suggested and present the results here.
    Note, however, that all voltages on that 8-pin connector vary as the blue power light (and the backlights on the screen) switch on and off (without any intervention from me).
    Typically, the blue light stays on for 5-6 seconds and off for 3 seconds. In between these two events, the orange power light comes on for about 1 second.
    For the few seconds that the blue light in on, the voltages are, indeed,...
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    Last edited by paulfxh; 12-09-2015, 02:13 AM.

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  • paulfxh
    replied to Acer LCD monitor on-off repeatedly
    in Troubleshooting Computer Displays
    Re: Acer LCD monitor on-off repeatedly



    Thanks for the comments, budm
    Well, here's another surprise. I have tried to repeat what I did and reported in my last post, but now I am getting different, but this time, the expected behaviour from the system as set up.
    Also, it seems I was mistaken in assuming that the ribbon cable from the main board to the screen was the backlight cable. The manual refers to this as the LVDS cable which provides data to the screen.
    The backlights are powered from the four connectors on the power supply board.
    ...
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  • paulfxh
    replied to Acer LCD monitor on-off repeatedly
    in Troubleshooting Computer Displays
    Re: Acer LCD monitor on-off repeatedly



    Thank you, Momaka, for your most instructive reply.
    Well, as I said, I had never taken a monitor apart before so I'm sailing in what are for me uncharted waters.
    Nevertheless, I'm starting to see light at the end of the tunnel.
    I hooked up the two boards together with the monitor keyboard and the four connectors from the screen to the power board.
    Only the ribbon cable from the main board to the backlights on the screen remained unconnected.
    Then with main power cord inserted I switched it...
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  • paulfxh
    replied to Acer LCD monitor on-off repeatedly
    in Troubleshooting Computer Displays
    Re: Acer LCD monitor on-off repeatedly

    Hi Momaka
    Thank you for your reply.
    Here's the power supply board:
    [ATTACH]124045[/ATTACH]

    And here's the main board
    [ATTACH]124046[/ATTACH]Re: Acer LCD monitor on-off repeatedly

    Hi Momaka
    Thank you for your reply.
    Here's the power supply board:
    [ATTACH]124045[/ATTACH]

    And here's the main board
    [ATTACH]124046[/ATTACH]...
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  • paulfxh
    started a topic Acer LCD monitor on-off repeatedly
    in Troubleshooting Computer Displays

    Acer LCD monitor on-off repeatedly

    LCD 21.5” monitor (Acer X223HQ) about 4 years old, worked fine until recently.
    Then started turning itself off and on repeatedly.
    Its behaviour, although bizarre, is remarkably consistent.
    So, starting up from cold (desktop computer attached), the computer boots normally and gets to the desktop screen.
    But 40 seconds after start up, the screen goes black, the blue power light on the monitor goes off and remains off for 3 seconds.
    Then the orange power light comes on again for about 1 second, followed by the blue power light and a fully functioning screen....
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  • paulfxh
    replied to New Members - please post your introductions here
    in Announcements & Related News
    Re: New Members - please post your introductions here

    Hi, I'm Paul.
    Lots of experience but almost all in software and very, very little in hardware.
    Now I've got an LCD monitor that I need help with so here I am.
    See you later.
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