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  • EEVblog #365 – ESR Meter Bad Cap Monitor Repair

    Posted on October 6th, 2012 EEVblog 14 comments


    Yet another dumpster diving LCD monitor repair.
    This time an LG SyncMaster monitor with bad caps.
    Using the Bob Parker ESR Meter
    Bob’s full article is HERE
    Forum Topic HERE

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    • Paul Collins M0BSW

      Another good video Dave ,nice nice to see how things are done correctly, you could make a fortune in your dumpster & E-bay.

    • Arnon

      hey dave I would like if you can make a video how to replace a cap (technics) in multi layer boards like computer motherboards because its very hard, not like in this single side PCB.

      thanks
      arnon

    • robert

      But is it legal?

      Who’s the owner of the trash…

      • JRR

        You could make it legal by providing an electronics recycling program. Heck, you could charge them what it would cost you to dispose of the stuff assuming you can’t fix it, then profit on the stuff you can fix.

      • http://www.eevblog.com EEVblog

        It’s legal under international Dumpster Diving law! Trash is trash.

    • http://www.eevblog.com/ Jan

      Did you really say ‘kaputt’ in the beginning of the video? Lol, we say this as well in Germany for broken things.

    • Agent24

      He says don’t bother changing the ones that test OK on the ESR meter, but remember if bad ones are in parallel with good ones you can get a false reading when testing them in circuit.

      More importantly however, since these things run hot, since there are already other failed capacitors of the same brand in the device, you might as well replace the lot otherwise you just have to come back and replace the rest later, and if you leave the crappy ones in there’s a higher chance of other parts failing due to stress from bad capacitors putting the whole circuit out of whack.

      Also note that you really should get capacitors that match the originals in terms of ESR being the same (little lower is acceptable) and having the Ripple Current Rating the same or higher.

      Otherwise you may well run into more problems sooner rather than later!

      • http://www.dgkelectronics.com Kalle Hyvönen

        I would have to agree with Agent24, if there’s bad caps and “good” caps of the same brand, always replace the good ones as well!! All they are gonna do is fail within a short period of time as well.

    • Eamonn McGonigle

      Hi Dave,

      An eerie coincidence: I happened to be doing almost exactly the same repair to an almost identical LG monitor on Sunday morning. Mine had an IC and a heatsink where your had 4 diodes and mine had some extra caps where yours had unpopulated spaced on the board, but otherwise it looks like the same PSU board. My dodgy caps were branded Samxon. There was only one bad one: a 1000uF 16v one (but I swapped all of them anyway).

      Thanks for the videos – I always look forward to them.

      Best Wishes,
      Eamonn

    • http://www.waltec.nl Qno

      Hi Dave

      Could you do some measurements with the ESR meter with the capacitor partly charged?
      Electrolitic capacitors form a layer that holds the charge. Does this have an effect on the ESR?

      Thanks,

      Qno

    • Worf

      Just a few notes.

      First – dumpster diving may not necessarily be legal – there are many laws around it and yes, garbage companies have been known to sue people for taking stuff out of the bins.

      Of course, since Dave didn’t actually “dive” for the stuff (they were put in the garbage area, but not in the dumpster), it can be argued it’s for “recycling” or general free for all.

      Second – clips are used to speed manufacturing. When monitors are sold for $100, after retailer profit, shipping/warehousing/etc, there isn’t actually a lot of money left. Also, if you’re building millions of the things, or want to automate production, screws slow things down significantly. Short of small runs, large runs with automated equipment means using adhesives or clips. (Plus, at the price, most people won’t bother repairing because a tech will probably charge an hour, and it’ll be $50+parts, so you just buy a brand new bigger one for $100 on sale…).

      Also, clips tend to self-align. There can be so many assembly errors with screws (and if the designer didn’t do the screw holes properly…).

    • PChi

      It looks like the capacitors closest to the diodes were cooked. As they have skimped on the diode heatsinking (none) the heat coupled through the PCB traces to the capacitors leads might be why they haven’t lasted. The capacitor manufacturer could be blameless.
      I liked the ESR meter.

    • Alecsander

      Hello mate, i usually do this for a living and i learned that is better to remove all the caps and put at least 3-4 25V/2200uf and it will never die :) (at least till the ccfl tubes die)

      Cheers!