Problem with LCD Panel board

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  • bammbammfran
    replied
    Re: Problem with LCD Panel board

    Hum ?
    since you have 5 volts in on 6 and ground on 3, I would think that when the 5 comes into 1 that 4 and 5 should turn on or at least try to.
    Bad chinese chip ? or something else is stopping it from turning on ?
    see what resistance you have on 4 and 5 to ground ?
    verify resistance on 1053 at R104

    Leave a comment:


  • jetadm123
    replied
    Re: Problem with LCD Panel board

    Suggest you re-measure the voltages of the OZ9936 as you did in post #12.

    Leave a comment:


  • mokie
    replied
    Re: Problem with LCD Panel board

    Here are photos of the new OZ9936 replaced. I did the best I could. Yes, pin 3 is connected to ground


    In summary, I have checked:

    - Secondary of both inverter transfomers. Around 460 ohms.
    - I have desoldered all capacitors and their capacity is ok (maybe they have high ESR?)
    - I have checked what I think are two fuses for the inverter zone. They are located near the OZ9936 and they are ok.
    - I have replaced the two main mosfets for the inverter zone which were opened. They were P609 and I replaced them with both P605.
    - I have resoldered all the connections in the high voltage zone.
    - Of course I have checked both lamps with an external inverter and they are ok.

    I don't know what more to do.
    Attached Files
    Last edited by mokie; 05-24-2014, 08:02 AM.

    Leave a comment:


  • bammbammfran
    replied
    Re: Problem with LCD Panel board

    can you post a picture of the new installed chip
    just for giggles, use an ohmmeter and check pin 3 to make sure it has a good ground

    Leave a comment:


  • mokie
    replied
    Re: Problem with LCD Panel board

    The voltages are exactly the same as before and the lamps doesn't even flash for a second.

    If I light the screen, I can see the image on it.

    Leave a comment:


  • budm
    replied
    Re: Problem with LCD Panel board

    So did the backlights lamps even flash for second?

    Leave a comment:


  • bammbammfran
    replied
    Re: Problem with LCD Panel board

    did you recheck the pins to see if anything is showing up at 4 and 5 and if 1, 6 and 7 were still the same as before

    Leave a comment:


  • mokie
    replied
    Re: Problem with LCD Panel board

    I've replaced the OZ9936 and I have the same problem, no backlight at all

    Leave a comment:


  • mokie
    replied
    Re: Problem with LCD Panel board

    ok ,thank you for all your help. I will be posting the results

    Leave a comment:


  • bammbammfran
    replied
    Re: Problem with LCD Panel board

    It appears to be not turning on.
    Hopefully that is all that it is.
    Lots of work for a board that you can get in China for $18 , but hopefully someone learned something from this project.

    good luck with the transplant

    Leave a comment:


  • mokie
    replied
    Re: Problem with LCD Panel board

    This is what I get. I guess that the OZ is cooked
    Attached Files

    Leave a comment:


  • bammbammfran
    replied
    Re: Problem with LCD Panel board

    OK, Your first post said shorted

    It still might be an OZ controller chip issue
    check pin 6 for around 5 volts in (7 is max per the datasheets)
    then see if pin one gets voltage when you power it on (might be around 3 volts) should be between 2 and 4
    then check 4 and 5 which should be the two pins that drive the P205
    pin 7 is the dimming voltage and would depend on what the dim was set at so it may be between 0 and 3ish.

    based on your picture with the pin 1 and the dot at the bottom left
    pins should be as follows
    8 7 6 5
    1 2 3 4

    Leave a comment:


  • mokie
    replied
    Re: Problem with LCD Panel board

    No, actually there aren't shorted. The problem was on the N-channel. If I check between drain and source (negative and positive respectively) I got 0.5 (OK) but if I turn on the gate there's no continuity between drain and source.

    Sorry for my bad explanation, I'm not english native.

    Leave a comment:


  • bammbammfran
    replied
    Re: Problem with LCD Panel board

    IF you check you old P205 and the G2 is shorted to S2 or D2, then the OZ is probably cooked

    As far as soldering: For some people , removing it is a little tougher than installing one. Make sure to flux it good first then add a glob of solder to your iron tip and spread it back and forth on the S and G side while lifting slightly on the chip, you'll have less chance of trace damage this way. If that is a problem, you can cut the pins on the D side one at a time with a new exacto blade by going straight down right where the pins enter the chip then unsolder the other side

    Leave a comment:


  • mokie
    replied
    Re: Problem with LCD Panel board

    - I don't understand well the first question, but when I turn on the monitor there isnt't any signal on the gate pin of any mosfet

    - Yes, I get 14.36 volts on both drains (and both mosfets, each mosfet has 2 drains)

    - The flashlight doesn't flash at all (with or without the 30 pin plug)

    Probably it will be that OZ9936GN. I think this is a good deal http://www.ebay.es/itm/2X-OZ9936GN-O...-/360619504921

    The problem will be the soldering though.

    Leave a comment:


  • bammbammfran
    replied
    Re: Problem with LCD Panel board

    Looks like power is getting there and that no fuse was involved

    That OZ9936GGN should be what sends power to the two P605
    It probably sends around 5 volts to one pin to turn the P605 on
    does the 5 volts show up and stay on ?

    go you get 14.3 on both P605 drains ?
    do the backlights flash at all ?? (leave the wide 30 pin plug that goes to the actual lcd panel disconnected when looking for a flash)

    Leave a comment:


  • mokie
    replied
    Re: Problem with LCD Panel board

    look at the picture.

    On the bottom, there is an IC with 8 pins. It's a OZ9936GN
    Attached Files
    Last edited by mokie; 05-03-2014, 01:52 PM.

    Leave a comment:


  • bammbammfran
    replied
    Re: Problem with LCD Panel board

    Check for dc voltage at the first corner pin of the P605 to make sure power is getting to them. Not sure if these are fused on this board since I can't see the bottom.
    The pin you will be checking will probably be connected to one of the capacitors that is right next to them.
    voltage may be 12-18 volts based on other boards I have seen.

    if voltage is not there, check for a surface mount fuse under the board

    If voltage is there, then you may have cooked the controller chip that is on the other side of the board. that chip,I think ? is an 8 pin

    good bottom side picture of this area might help

    Leave a comment:


  • mokie
    replied
    Re: Problem with LCD Panel board

    any help?

    Leave a comment:


  • mokie
    replied
    Re: Problem with LCD Panel board

    oh god, I'm stupid. Rookie error. The conector was REVERSE!.

    Now I have the monitor working but without backlight. I've checked both mosfet of the inversor and they are ok (AOP605).

    I've checked the lamps with an external inverter and they are fine
    Last edited by mokie; 05-03-2014, 11:08 AM.

    Leave a comment:

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