CF53 Screen goes white replaced screen now more issues after screen change

Discussion in 'Panasonic' started by KelBun, Jun 27, 2017.

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  1. KelBun

    KelBun Newbie

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    I have a CF 53 where the screen was going white and it was intermittent so i replaced the screen which the new screen worked for several days with no signs of white screen. This morning i decided to put the screen surround on and turned the computer on , the new screen did not work so i though i had bumped the connection ,pulled the screen surround off and checked and found it all in place. I connected a external screen which works fine as well as checked the settings which seem fine. I am wondering if the cable could be at fault going to the screen.
     
  2. SHEEPMAN!

    SHEEPMAN! Freelance

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    You did this with a battery installed? Could be a cable but most likely a fuse.

    You are talking of the screen bezel, yes?
     
  3. Shawn

    Shawn Crackpot Search Ninja and Options Whore

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    CF 53's seem to have video/lcd issues. You will find many on ebay with video problems.
    I had one that I tried 4 different lcd panels and a new lcd cable. I finally determined the motherboard had developed a problem.
    That was a $300 lesson for me.
    Look for burn marks where the LCD cable plugs into the motherboard.
    Otherwise a new cable may solve the problem for you.
     
  4. KelBun

    KelBun Newbie

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    Yes the screen bezel is what i put back on. I have not got back to it. Is there a fuse on the screen circuit ?

    Thank you, i will look on the mother board for burn marks.
     
    Last edited by a moderator: Jul 5, 2017
  5. Shawn

    Shawn Crackpot Search Ninja and Options Whore

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    several fuses.
    very tiny.
     
  6. CWB32

    CWB32 Need parts for my flying saucer.

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    yep ... tiny indeed .
    some are about 1/4 the size of a grain of rice , others are bigger .
    pulling the battery and using a set of needle tips on a dmm set to the low scale resistance ...
    check the fuses (they will be labeled as such) .
    (do not use "diode check" ... some meters will apply more than .75VDC and this will ruin some semiconductor junctions/devices)
    replacing those fuses requires a good eye , steady hands and a micro-tip low wattage iron and the use of *real* rosin fluxed lead based solder (63/37 comes to mind) .
    i am not going to say it is a difficult task to find/repair them but there were times when i thought that inviting my ex-mother-in-law over for the weekend would have been preferable .
     
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  7. Toughbook

    Toughbook Drop and Give Me 20!

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    I've always had good luck wiping the solder away with the tip of an iron on one side of the fuse... Grab it with some low pressure hemostats, then desolder the other side. I then clean up the pads a little and tin them... Then just heat each side for the replacement harvested off another mobo... Or even a Buss fuse works if space allows.

    You are definitely checking for continuity... Interesting about the "Diode Check"... I'll have to keep that in mind.
     
  8. Shawn

    Shawn Crackpot Search Ninja and Options Whore

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    I can tell you that replacing fuse will probably not solve video issues on a CF53.
    They have some sort of design defect. Although cables are a known issue also.
    Cables overheat and short out. Connection on MB near cable overheats and shorts out too.
    This seems to take out some part of the video circuit.
    I checked and replaced all the fuses and the cable on that CF53J that I bought. Along with 4 different panels. No joy. The MB was toasted. Parted it out..

    Personally, I won't buy another CF53..I will stick to my "antique" CF 52 for a daily driver.
     
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  9. SHEEPMAN!

    SHEEPMAN! Freelance

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    I'd look for tracks where you have been.
    It quit after you replaced the bezel so check there first. Is there a fuse in the upper half guys? Then take a microscopic look near where it plugs into the mobo.
    I use a camera set on macro.
    I have two or three untested screens if you want to try another one.
     
  10. CWB32

    CWB32 Need parts for my flying saucer.

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    yes ... one can ruin parts checking them .
    many years ago , the old standby in shops and on benches was a triplett vom (pick a model) .
    a lot of techs were popping transistor junctions and small signal diodes on the low ohms and continuity scales/settings .
    in these positions 1.5 or up to 22.5 volts was available at the probe tips (i still have 2 of these types meters on the shelf) .
    a "normal" semiconductor junction is made to handle .3 to about 1.2 volts in reverse (aka : PIV) depending on the device type .
    in more modern semiconductors such as mosfets (and there are bunches of them in use in laptops) the gate reverse breakdown voltage can be exceeded by some dmms .
    how do you tell if a meter is safe to use on/around (as in : where does that pc trace lead to) ?
    the short answers are :
    read the meter specs
    measure the tip voltage with another dmm in the low ohms/continuity and "diode check" modes .
    a good meter is designed to not pop semiconductors .
    with a 15 dollar yakkaweewee special , all the bets are off .
    a good meter (say , fluke , for one) is designed with the above facts in mind ... they are proud of their stuff , the specs and prices reflect this .
    i have a meter that i have been using for years and was/is my service bench workhorse ... it has .1 volt at the probe tips (and very current limited) and the diode check applies .75 volts (again very current limited) in order to overcome the Vfwd (forward band-gap junction voltage) of most semiconductor devices .
    there are semiconductor devices that fall outside of these average ranges (think : gaasfets , zener diodes and several others) and as such will require different test set-ups .
    also ... it is not just the voltage that is important ... once the Vfwd and PIV are exceeded (and this is actually a test in some devices) , the current that can be provided/limited to the probe tips is of equal importance .
    (and why i mentioned the "limited current" availability of my meter)

    there is more to this topic , the tack of this is to provide some information to help prevent creating a problem where none actually existed before .
     
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