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Belinea Model: 10 17 10

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    #1

    Belinea Model: 10 17 10

    Got this LCD for almost nothing, knowing it was not working

    When it is turned on, monitor cable not connected to PC it comes up with 3 horizontal split sections in white grey/black-ish and white, the grey/black-ish fades to white(er) before the monitor cuts power.

    The upper secion has some "noise" or black/blue small lines that also fades (to white)

    When the monitor cuts power the LED switches from green to yellow (standby)

    The +3.3v & 5v are stable (untill the monitor cuts power) 3.297v & 5.000v respectivley.

    +12v is first at 14.1 for a brief period, then 12.26v next it spikes up but goes back to 12.26v and after a few more seconds power is cut...

    If I remove all cables from the main PCB except the powersupply cable, and cable going to the front PCB with powerbutton the issue is still the same, i.e. without lamps and stuff even being on it cuts power and spikes the +12v in the same manner

    So therefore I am assuming the powersupply is faulty and need some help in diagnosing it, it has a 10 pin connector with power outputs, in this order:

    Code:
    +3.3v
<empty>
+12v
+12v
GND
GND
+5v
+5v-fix
GND
P-Saving
Volume-C
    5v-fix as the name implies always has 5v standby power, for soft power-on...

    P-Saving reads 2.880v and Volume-C: 0.770v

    During all this testing (I had to turn on and off the monitor for every reading) it twice stayed on, then the picture was 100% white with what looked like a trinitron line straight across the screen at 1/3 from the top, and that part was also visibly "different" from the white below, can't describe it better than that... Also the +12v reading was stable at 12.26v then...

    Everything on the PCB looks fine, the caps are all Lelon RGA except for 2x RXJ and one small TEAPO, the bulkcap is of unknown make

    All PCBs has the text "Acer Peripherals" written on them...

    Can I test the PSU by shorting +5v-fix to Ground and connecting a PC harddrive as ballast to +12v and +5v? Or how do I turn on the PSU on it's own?

    EDIT; and learned the hard way that the heatsink with the single mosfet holds 120VAC; touched it with my underarm when probing with the DMM Fortunantley the power stayed in my arm and did not travel to the other arm where I had my antistatic wrist strap connected (that is like last time I got shocked by a PSU...)
    Attached Files
    Last edited by Per Hansson; 06-16-2006, 03:56 PM.
    "The one who says it cannot be done should never interrupt the one who is doing it."
    Tags: None
    #2
    Re: Belinea Model: 10 17 10

    Hi Per Hansson

    Guess you are probably looking for the definitive answer on this but I am no guru on tft's
    (worked on a few but not on a day to day basis)

    If it is the power supply and you dont have a schematic, I would track down info on that big chip.
    There is a cap that may be bulgding slightly behind it, bit hard to tell from the photos
    May be worth checking it out
    (could be the problem or symtom of the problem)
    Since it has acer stamped all over it it may infact be a rebaged acer
    (but I am not sure who makes what these days)

    OK hope someone who works with these thing on a daily basis can give much better advice then I

    BTW its a worry to hear you are trying to become "1 with the Light Bulb"....BE Careful
    Live switch modes and wrist straps ??????
    Attached Files
    You step into the Road, and if you don't keep your feet, there is no knowing where you may be swept off to." Bilbo Baggins ...

    Comment

      #3
      Re: Belinea Model: 10 17 10

      Originally posted by starfury1
      If it is the power supply and you dont have a schematic, I would track down info on that big chip.
      There is a cap that may be bulgding slightly behind it, bit hard to tell from the photos
      May be worth checking it out
      (could be the problem or symtom of the problem)
      Since it has acer stamped all over it it may infact be a rebaged acer
      (but I am not sure who makes what these days)
      Well, I first need help to test the PSU, I think it might be faulty but I do not know... So I need to know how to send it the "power on signal"

      All the caps look visually fine, both the tops and bungs looks good, of course that could still mean problems since the caps are Lelon and could have failed silently...

      The big chip, it is a "ST TDA7496" Which is a "5W+5W AMPLIFIER WITH DC VOLUME CONTROL" i.e. it is the chip which drives the two built in speakers...

      Originally posted by starfury1
      BTW its a worry to hear you are trying to become "1 with the Light Bulb"....BE Careful
      Live switch modes and wrist straps ??????
      Haha, yea, I always advice (on these forums to) to not wear a grounding strap when working on powersupplies, but we all known to not work as we teach right?
      "The one who says it cannot be done should never interrupt the one who is doing it."

      Comment

        #4
        Re: Belinea Model: 10 17 10

        I'd disconnect the built-in power supply and connect an ATX one - to test if only the power supply is bad and the rest of the electronics work.

        Comment

          #5
          Re: Belinea Model: 10 17 10

          Originally posted by Rainbow
          I'd disconnect the built-in power supply and connect an ATX one - to test if only the power supply is bad and the rest of the electronics work.
          I was thinking of doing that, but will it be ok to just ignore that P-Saving line at 2.880v?

          I.e. only connecting up +5VSB, +5v, +3.3v and 12v?
          "The one who says it cannot be done should never interrupt the one who is doing it."

          Comment

            #6
            Re: Belinea Model: 10 17 10

            Doh!
            had I had looked at the overview pick more closely I would have seen it was connected to the speakers, still really wasn't expecting to see the Audio amp ic on the psu pcb.
            ( I was busy looking at the pcb close up pics)

            Seems all the action happens on the under side,
            As to the supply...I would lightly resistive load on the rails and I suspect the pwr switch is a momentary type switch that causes a flip flop type action to happen
            I would mimic the switch , but again no expert and purely guess work on my part

            I've been shaking the net to see if anything falls out but nothing of any help
            You step into the Road, and if you don't keep your feet, there is no knowing where you may be swept off to." Bilbo Baggins ...

            Comment

              #7
              Re: Belinea Model: 10 17 10

              Rainbow sugestion would be what Id have tried if it were straight power connection but I am wondering what the interaction is if any.
              Like is that main pcb telling the psu to shut down because of a fault
              depends I suppose on how p,save line works...and that I don't know
              I am guessing you would get away with a quick power up test but its not mine to risk
              Id rather be sure then sorry....thats the nice thing about have a few of the same type about, you can play board jockey and see which one the problem pcb Oh well (and hopefully not blow up a working PCB)

              Really wish I could be of more help to you Per H
              Last edited by starfury1; 06-17-2006, 04:39 AM.
              You step into the Road, and if you don't keep your feet, there is no knowing where you may be swept off to." Bilbo Baggins ...

              Comment

                #8
                Re: Belinea Model: 10 17 10

                Anyone else have anything to say about testing the monitor with a normal PC PSU?

                I'm a bit weary of trying it...
                "The one who says it cannot be done should never interrupt the one who is doing it."

                Comment

                  #9
                  Re: Belinea Model: 10 17 10

                  Well, finally tested with a normal PC PSU, the issue was the same, the monitor powered up just fine like before with 3 section of black and white then it cut power to the LCD, of course it could not turn off the powersupply but that did not seem to matter...

                  So I guess the culprit must be that large main PCB which everything connects to, because as I said before it still turned off with nothing else connected to itself (i.e. without the cable going to the PCB the lamps are connected to and the other two cables leading into the monitor itself)
                  "The one who says it cannot be done should never interrupt the one who is doing it."

                  Comment

                    #10
                    Re: Belinea Model: 10 17 10

                    Per, I also buy these cheap, but I look for two at a time when I get them.
                    One with blown main board and one with smashed screen.
                    Then as star said I use best of each and chuck the rest.
                    Jim

                    Comment

                      #11
                      Re: Belinea Model: 10 17 10

                      What are the ratings of these capacitors? (pic is of the main PCB which I think is the culprit...)

                      Is the top number the uF rating and the middle the voltage rating?
                      Attached Files
                      "The one who says it cannot be done should never interrupt the one who is doing it."

                      Comment

                        #12
                        Re: Belinea Model: 10 17 10

                        Yes, the top number is the capacitance and the middle number is the voltage.
                        Apparently, depending on the application, SMD capacitors are more likely to fail than their leaded counterparts.
                        My first choice in quality Japanese electrolytics is Nippon Chemi-Con, which has been in business since 1931... the quality of electronics is dependent on the quality of the electrolytics.

                        Comment

                          #13
                          Re: Belinea Model: 10 17 10

                          Ok, but what's up with that cap in the middle? Reads:

                          08
                          68
                          25x
                          "The one who says it cannot be done should never interrupt the one who is doing it."

                          Comment

                            #14
                            Re: Belinea Model: 10 17 10

                            Probably 68uF/25V

                            Comment

                              #15
                              Re: Belinea Model: 10 17 10

                              Yes, it is 68uF, 25V.
                              (Beware of decimal points which can be hard to see)
                              My first choice in quality Japanese electrolytics is Nippon Chemi-Con, which has been in business since 1931... the quality of electronics is dependent on the quality of the electrolytics.

                              Comment

                                #16
                                Re: Belinea Model: 10 17 10

                                I've ordered some caps from Elfa, lets see how this goes...
                                "The one who says it cannot be done should never interrupt the one who is doing it."

                                Comment

                                  #17
                                  Re: Belinea Model: 10 17 10

                                  Installed all the new caps, surface mont caps where really easy to work with, kinda wishing mobos would use them instead... Much less hassle to remove and no cleaning of holes needed of course ;-)

                                  But when I turned the thing on the issue was the same as before I.e. I get a couple sections of the screen in black/white and then it shuts down... And I also previously tested with both another powersupply (PC ATX PSU) and without the lamps and other stuff connected so I am sure that the issue is with this "main" PCB...

                                  Anyone have any idea as to what could cause this type of failure mode?
                                  "The one who says it cannot be done should never interrupt the one who is doing it."

                                  Comment

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