Cooked inverter on Dell 2005FPW

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • sweetdaddyjones
    New Member
    • Feb 2014
    • 7
    • USA

    #1

    Cooked inverter on Dell 2005FPW

    Hi, all! First off, I want to thank everyone for making this such a great resource for learning and assistance--several others have had similar problems with this very same monitor, so by reading through those old threads I was able to take my diagnosis/troubleshooting at least this far (and found the schematic too!) Basically, I have a 2005FPW whose backlight started to fail a few months ago; at first, simply powering down the monitor and turning it back on would make it work again for a little while, but soon the screen would remain dark even as the power LED indicated the monitor was on. I knew virtually nothing about how monitors worked at the time, (and only a little more now ;x), but I remembered reading that when monitors failed thus, it was often simply a matter of replacing a couple of blown capacitors, so I decided I'd try to fix it myself. Upon inspecting the monitor's guts, no obviously bulging capacitors were visible, but the problem (or part of it anyway) was obvious: one of the 6 transformers that drive the backlight CCFLs had clearly burnt out, discoloring the surrounding board. (VERY similar to what's seen here: https://www.badcaps.net/forum/showpo...91&postcount=6) My first thought was, "Hey, I have a ton of spare inverters from broken laptop screens--why don't I just use one of those to drive the CCFL in place of the one that burnt out?" Taking a multimeter to test voltages on the board, There was immediate arcing between the probes and the chassis. After removing the shorted transformer, this is no longer the case, and I can use the DMM to probe points on the board without visible arcing. I was then going to hook up my replacement inverter to make sure it would drive the CCFL whose transformer burnt out, but noticed that it appears the leads from the CCFL itself appear to have arced, as the black plastic around the LCD has melted, exposing the lines (as well as the insulation of said high voltage lines), which leads me to believe hooking up another inverter would not cause the lamp to light, but just start high voltage arcing across the wires before it got there, maybe even destroying the new inverter. Basically, I realized that what I had ASSUMED to be the CAUSE of the problem (i.e. burnt transformer) could in fact have been a symptom of another problem (i.e. arcing HV wires going to CCFL). At this point, I need the insight from someone who understands how these things work better--what do you think is going on here? What would generally cause these symptoms? Is it possible that melted transformer really was the root cause of the problem, or is it more likely the arcing wires of the CCFL CAUSED the transformer to melt, or is something more complicated going on? If the bulb itself were dead, could that cause the wires to heat up, arc, short, and melt the transformer? Any insight would be greatly appreciated!

    Thanks,

    Nico
  • Lumberjack777
    Badcaps Veteran
    • Dec 2010
    • 464

    #2
    Re: Cooked inverter on Dell 2005FPW

    The arcing of the wires would cause the inverter transformer failure. Even a bad transformer won't force wires to arc. It's a break in the insulation of the wires that causes that. It sounds like you are saying the break and arcing might extend inside the panel a little. If thats the case you'll need to take the panel apart to have access to the bad area. Sometimes it's possible to open up just the one side and have access to the wires. (if you have to take apart the entire lcd panel; keep track of diffusion plastic sheets, and try not to allow contamination with dust or pet hair)
    If you splice in new wires or use the old ones. Be sure the insulation tape extends beyond the break point of the wires. Those CCFL's run high voltage, and the wires will try to arc to metal ground any way they can. Even a pinhole size hole will arc.
    If you can test the CCFL wiring before you reassemble (or solder on the new transformer)that's the best way.

    Comment

    • R_J
      Badcaps Legend
      • Jun 2012
      • 9534
      • Canada

      #3
      Re: Cooked inverter on Dell 2005FPW

      If the ccfl is cracked it can still light (had 2 monitors like this) On the one monitor the leads to the ccfl that was cracked were arcing, I think if the lamp does'nt draw enough current, the inverter will increase the voltage to it causing the leads to arc or corona (smell of ozone)
      My test inverter would light the good lamp but would not light the bad one, however the monitors own (dual) inverter would light both lamps but the bad lamp leads were arcing.
      This was on a Compaq/HP HSTND-2301-ac
      Last edited by R_J; 03-25-2014, 09:21 PM.

      Comment

      • sweetdaddyjones
        New Member
        • Feb 2014
        • 7
        • USA

        #4
        Re: Cooked inverter on Dell 2005FPW

        Thanks a lot for the helpful and speedy replies, mates! Sorry bout the delay--I had typed up a[n unnecessarily] detailed response the next morning, but my browser crashed before I posted it, and I was too discouraged to replicate it lol. Basically, it said that I suspected this was the case, but had hoped to avoid having to disassemble the panel itself as this exponentially increases the chances I'll break something during the reassembly phase...I'm great at taking things apart, but I'm still working on the putting-em-back-together end of things ;X

        At this point, I also am considering taking an entirely different approach, which would undoubtedly present its own challenges, but I was wondering if you good folks have any input: Since I already have to disassemble the panel, and to get it working again in the 2005FPW means repairing melted wires and/or buy a replacement CCFL on TOP of wiring and mounting the new inverter inside, I was debating trying to instead harvest the panel for use with a broken samsung LS20A250 monitor I have. The only problem with the LS20A250 was the panel itself (cracked TFT/glass), and I already disassembled the panel, removed the cracked TFT/control board, and put the remaining pieces back together, confirming that the LED backlight still works and lights up the whole panel evenly. (and boy is it BRIGHT without that dark TFT in the way!) The working panel from the 2005FPW (lm201w01-bk) uses the same 30-pin connector, and even sends 2 channel LVDS with the same pinout--the only difference is in the last 3 pins, which are all the same and carry supply voltage (samsung is 5V, lm201w01-bk wants 12V)... If I lay the intact TFT from lm201w01-bk over the LED backlit panel from the LS20A350, connect the logic board (execpt for the last 3 pins,which get 12 V), my gut instinct says fewer things to solder means fewer chances for me to screw things up, but then again, the panels aren't the same dimensions...

        You guys are the experts, what do you think? What's the path of least resistance to a working monitor? (And does it seem like I [roughly] understand things correctly from what I've posed?)

        Comment

        • Lumberjack777
          Badcaps Veteran
          • Dec 2010
          • 464

          #5
          Re: Cooked inverter on Dell 2005FPW

          To be honest I've never switched panels with another model. Maybe somebody with more experience in that area could help you, or state that it definitely could, or would not work.

          What'd I'd do because I'm a cheapskate (and because we repair many recycled monitors that we sell cheap, or give to low income families) Basically, we just try to get a few more years out of them, for as low of cost as possible. I would..........

          Take 1/2 of the panel apart. Carefully. Enough to remove the ccfl lamp assembly. If the lamps were not cracked I'd wrap the exposed wires with electrical tape (or shrink wrap tubing if I spliced in new wiring) Then plug in the connector with the lamps still out and turn it on. If any lamp had a problem I'd carefully remove the silicon end cap and solder the wire back properly. If the ccfl's are still good, it's just a matter of getting that faulty wiring to quit arcing.

          Comment

          • sweetdaddyjones
            New Member
            • Feb 2014
            • 7
            • USA

            #6
            Re: Cooked inverter on Dell 2005FPW

            Thanks again, Lumberjack...I think I'll follow your advice, barring a slew of panel swap endorsements.

            Comment

            • sweetdaddyjones
              New Member
              • Feb 2014
              • 7
              • USA

              #7
              Re: Cooked inverter on Dell 2005FPW

              Help! As per Lumberjack's reccomendation, after very carefully fitting 3 salvaged CCFLs in the frame, reassembling the panel and making sure all 6 lights are now working, I may have botched the job during the final phase of testing: while laying the display itself (the part connected to the logic board that actually displays the image--not sure how to refer to it--TFT?) atop the reassembled frame, one of the ribbon like connectors that joins the TFT in front of the panel to where the driver board rests on the back just sort of popped loose. My heart has stopped lol. What should I do?
              Attached Files
              Last edited by sweetdaddyjones; 04-08-2014, 12:38 PM. Reason: Added photo

              Comment

              • spleenharvester
                Badcaps Veteran
                • Mar 2010
                • 894
                • UK

                #8
                Re: Cooked inverter on Dell 2005FPW

                As far as I know that panel is now beyond repair. There's no way of refastening those things.
                Dell E7450 | i5-5300U | 16GB DDR3 | 256GB SSD

                Comment

                • sweetdaddyjones
                  New Member
                  • Feb 2014
                  • 7
                  • USA

                  #9
                  Re: Cooked inverter on Dell 2005FPW

                  *SIGH*. I feared that was the case. I was SO close.

                  Comment

                  Related Topics

                  Collapse

                  • x_orange90_x
                    Vizio E55-E1 bad backlights or bad inverter?
                    by x_orange90_x
                    I just got this tv today and it appeared to have no backlight on. After taking off the rear cover and checking again in the dark I can see that MAYBE one quadrant is lit.. But still it's quite dim. I was going to check the LEDs with my tester, and I found LED 1 and LED 2 + pins on the wire from the inverter, but I couldn't identify a ground. Nonetheless I tried using a mounting screw on the inverter board and also the chassis as ground but regardless my tester reads 300 which is what it reads when there is no voltage draw.

                    I don't know how exactly to test the inverter itself. Is it...
                    01-29-2025, 09:24 PM
                  • Gentian
                    APSINT3636VR 3600W APS INT Series 36V DC 230V AC Inverter/Charger schematic
                    by Gentian
                    I have a tripp-lite aspint 3636vr inverter charger which blow some of mosfet transistors. I replaced them repaired also the driver circuit and tested but the mosfets burn again.

                    It work very well as inverter and also as charger if I let the rear switch in auto mode (inverter) and charger only(charging) but in auto when I connect the feed line 220V AC first time it pass ok to line and start charging the batteries but when I remove the feed line it pass to inverter mode and if I do it again the second time when passing from charging to inverter the Main transformer start making a...
                    03-06-2023, 07:07 AM
                  • valvashon
                    Insignia NS-LCD19-09 (PS OK, Inverter problem?)
                    by valvashon
                    For some reason I'm just not going to let this 19" TV defeat me. I guess because I have a schematic to work from I feel like I'm oh so close.

                    History- while adding a turn-on circuit I let a small screw roll under the power board. Worked through all of that circuitry, probably replacing a MOSFET and PWM controller that were not bad but I was following the service manual. Finally figured out that the power supply is in working order when the inverter section (for the backlights) is disconnected. When the +12 supply to the inverter is disconnected the +12 and +5 will come up...
                    01-04-2024, 01:44 PM
                  • eccerr0r
                    A modified sine wave inverter + a grid tie inverter?
                    by eccerr0r
                    If I had a solar fed grid tie inverter (GTI), a modified sine wave inverter, and a power outage occurred, what would happen if you disconnected mains, backfed the modified sinewave inverter (MSI) into house power, and hooked up the GTI to the output of the MSI, would it work?

                    Next thing is trying to charge the batteries using solar power, but that's another issue ...
                    08-31-2023, 09:14 PM
                  • caseyjay_48
                    Sony KDL-46BX450 Inverter Troubleshoot Logic
                    by caseyjay_48
                    I am currently on a troubleshoot of 46” Sony KDL-46BX450 tv. I came back from Washington to Texas on medical emergency and had to leave all my tools up there. All I have is a couple of screwdrivers and a dvm. I wish to ask the community a troubleshooting question. Please forgive stupid questions as meds I am taking produce brain fog.
                    I have well maintained Sony KDL-46BX450. It went black one day. After turn-on, I get solid green light and Sony logo in screen center for about 1-2 seconds, then black. No blinking LEDs, no hissing. Flashlight test shows screen characters dimly viewable,...
                    09-23-2022, 08:08 PM
                  • Loading...
                  • No more items.
                  Working...