Hacked Gadgets Forum

February 1, 2012

LCD Monitor Repair – Defective Capacitor

at 2:21 pm. Filed under DIY Hacks, Electronic Hacks

 

You have probably heard about the capacitor problems that have plagued the motherboard and computer power supply manufactures. Well other mass produced electronics are not immune to this issue. Viktor was given an LCD monitor once it was determined to be non-reparable by a local repair shop. These days local electronic repair shops are basically board swappers, their flowchart will point to a defective board in the system and if it is worth replacing it that is the fix. Only problem is that the board for a piece of electronics that is 2 or 3 years old will probably be more expensive that a modern and probably better new replacement. Not to mention that the repair shop will probably want a hundred bucks for bolting in the new board.

After a visual inspection of the circuit board inside the monitor it was quite obvious that one of the capacitors was defective, you can see it in the picture (the one with the bulge). After replacing this capacitor the monitor magically came back to life. I wonder if the repair shop employees knew to look for this, even if they sis do they have a soldering iron on hand would be the next question…

 


 

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17 Responses to “LCD Monitor Repair – Defective Capacitor”

  1. MasterFX Says:

    Many LCDs have this problem. My Samsung Syncmaster 226BW had this problem after 5 Years (7000 hours runtime => Service Menu). At first the time the Display took to turn on was longer than normal (30 Seconds or so). After a couple of weeks it tooks about 5 minutes. After 3 minutes it began to flicker and 2 minutes after it was ready and everything was ok. So I replaced the 820µF and 330µF 25V (which were visible inflated) and everthing was OK.

  2. Derek Tombrello Says:

    As a “local service shop” owner myself, I found this to be quite insulting! We regularly replace defective components as opposed to “board swapping” when practical. “Board swapping” is only a last resort when all else has failed.

    Speaking for myself, when my dad was teaching me electronic repair as a kid, he didn’t only teach me how to replace components. What he taught me was so much more valuable than that – in all aspects of life. He taught me how to reason; how to think; how to troubleshoot. Since that time, twenty-five years ago, I have been a professional consumer electronics technician, without the “benefit” of ever having earned a degree, and usually without the benefit of schematic diagrams. Yet I am still able to troubleshoot to the component level.

    I am sure that most repair shops are of the same mentality. The problem lies not with the technicians, but with the design of today’s disposable technology.

  3. Stuart Clough Says:

    Having been through this problem, I recommend using caps with a higher working voltage. That is instead of a 25v cap use a 35 or 50 v cap.

  4. dave96z34 Says:

    had to do that many times on tvs video cards and some power supplys.

  5. dave96z34 Says:

    I agree Stuart Clough its safe and posibly better for the pice to to this.

  6. Tek Says:

    sssshhhhhhh!!!!!! I like all the free monitors and lcd tv’s I get handed to me to since their broken and disposable.. Coupla cap’s and I have another tv to craigslist… heh heh…

  7. Alan Parekh Says:

    Hi Derek,

    Good to hear your shop still troubleshoots down to the board level in an industry that is moving away from that. I wasn’t trying to paint every service company with the same brush. As you know most manufactures are not building their equipment with serviceability in mind and not providing things like schematics to the front line repair staff is a good example of this. The new troubleshooting guides of many systems is a high level diagnostics flow chart which ends at identifying the culprit board.

    With the low cost of most of the stuff being sold I think it will simply cost more to fix than to replace. I am thinking that the cheap $25 DVD players is a good example of equipment that can’t even be cracked open and looked at before the bill is more than a new one would cost.

  8. Derek Tombrello Says:

    What’s really bad, Alan, is that most companies do not even produce replacement BOARDS more than two years after the device is manufactured, so even board swapping becomes impossible!

  9. MrMaigo Says:

    I’ve replaced caps on all my LCD monitors. When the lowest bidder wins, we all lose.

  10. Says:

    That’s a terrible shop if they couldn’t fix this! It’s literally a 2-minute fix. Examine board, find failed capacitors (they’re the ones that are bulging and leaking!), desolder them, solder in new ones. Add an extra few minutes if you don’t have a stash of them handy and have to find one to remove from an old junk board.

    I did this too when my display started refusing to power up (LED comes on, then the whole thing shuts off again). Just opening the silly thing was much more difficult than the actual repair! Swap out two capacitors from an old PC board and it’s good as new, a $400 display repaired for $0 worth of parts and 5 minutes worth of work!

  11. robert Says:

    It is sad that after a few years our consumer products are considered obsolete by continuing improvements in technology, and thus may not seem worth the cost to repair. But board swapping is (or supposed to be) a cost saving measure. The bad boards are returned to a factory service center where there are automated diagnostic tools to find the bad component(s) and a custom production line to repair the boards. A local service shop only needs to follow a simple procedure (swap the boards one at a time until the problem goes away) and thus doesn’t need someone with the knowledge of how to troubleshoot or the skill to repair. That way less trained people can be hired, and the fairly complex device can ber put back into service quickly. The defective parts can be fixed better, uniformly and more cheaply in a factory than in the back of a shop. Of course the ultimate board swap is just to swap the whole item. How do you think all those “factory refurbished” items come about.

  12. robert Says:

    Did you actually replace the capacitor in the board? A neat trick I’ve seen is motherboards capacitors replaced by cutting the top off and carefully removing all the material down to the wires inside the capacitor, leaving them so that you can solder a new cap directly to those wires — instead of trying to desolder, reopen the through-holes and solder in the tight space. You might not even have to remove the board. The new cap might stick up an inch or so, but then its even easier the next time!

  13. Fuming Solder Says:

    Wouldn’t it be nice if every faulty capacitor had a convenient bulge right at the top and it was located right next to the exact same capacitor so you can easily compare! I’ve seen enough of shorted and dried out electrolytic caps that did not look ANYTHING different from their good counterparts. Come to think of it, the transistors in switching power supplies fail just as often or more often than caps, so this was a lucky chance repair, really. Visual checks will only get you so far.

  14. Sylvain Says:

    Hi from France,
    I’ve got many HP1740 LCD and 9/10 of time the problem is with the ac socket ! Just add some solder on the 3 pads and it’s OK …

  15. Erik Says:

    I usually replace all capacitors on the secondary side of the PSU after one fails. They only cost a dime (or two) and , for a little bit more, I put in the ‘special’ hi-frequency powercaps since the others won’t last much longer.

  16. Warranty Voider Says:

    I often have to do repairs like this to with some of the industrial controls my company deals with. The factory wants $5,000 for a new control. A “refurbished” one (which is actually new) is $4,000. They refuse to do repairs on them. I can replace everything on the board in about 2 hours as a repair for about $25 in parts (plus another $100 for an EPROM from the factory if necessary). I always add a couple of hours for testing (and it actually does take 2 hours). So for less then $400, they’ll have a control that’s almost brand new minus the board and casing.

    And, Derek, you’re part of a dying breed, which is very sad. I’ve known 3 people personally in my life who own or run TV repair shops, one having been next door to my business. They all only changed out the board instead of doing the component-level repair. As authorized techs, they were required by the factory to send the boards in so the factory (supposedly) could do quality control. This made the repairs really expensive and took forever since a replacement board could take up to 2 months to get in and cost more than getting a new TV of the exact same model. But, since most customers have to pay $50 when they drop it off as a “diagnostic fee,” they don’t want to waste that money so go ahead and have the repair done. It also keeps waste out of the landfills.

  17. steve cochran Says:

    keep up the good work this will help many thanks

    steve

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