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Post Your Repair Tips And Links!

Discussion in 'Repairing Electronics' started by ElectroMaster, Feb 10, 2011.

  1. Tann-44

    Tann-44 New Member

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    Here's a handy tip if you get called away from a repair to answer the phone or deal with some..take a photo of where things go before pulling it apart and if needed be colour mark plug in connections..
     
  2. Tann-44

    Tann-44 New Member

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    Speaker test loads for working on power amps is a must....I built my many years ago from banks of metal clad resistors large fined heatsinks plus twin fan cooling... connections are via binding post/speakon/jack and the front panel have power meter plus scope and DMM OUT.


    for more ideas check champ electronics for a look how he made he's...it's a 1000w per side.
     
  3. unclejed613

    unclejed613 Well-Known Member

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    X10 circuit for 8 ohm dummy loads...
    shown is a scope adaptor for an 8 ohm dummy load. the trimmer cap is adjusted for flat-topped peaks on a clipped signal. this circuit is for a 1Meg scope input impedance. the wiring from the adaptor to the scope on mine is RG-214 teflon coax but can be any coax cable.
     
    Last edited: Jan 22, 2012
  4. dave

    Dave New Member

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  5. Tann-44

    Tann-44 New Member

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    Working on many different type's of audio equipment you may come across ones with xlr/jack/phono i/ps etc..and even the older 5 pin din connectors build a yourself a plug adaptor box so you can go from din..xlr..phono etc..
     
  6. dilan silva

    dilan silva New Member

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    bad "zoo"noice from stereo audio setup.. when power supplied

    solution - smoothing cap
     
  7. diy didi

    diy didi Member

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    Hi. I dont see circuit. Please post again please!!
     
  8. tvtech

    tvtech Well-Known Member Most Helpful Member

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    If you ever feel the urge/or need to work on a CRT TV please do the following first:

    1. Make sure the unit is unplugged from the Mains source. Unplug the Mains lead.
    2. Take an Insulated lead ( like from your DMM) and push the part that fits in your Meter under that thin silverish thin wire strap that goes around the back of the tube. Push it under that. Make sure it stays there while you take the other sharp end and push/force it under that Rubberish cap with a wire coming out of it at the top of the back of the tube.

    Sorry, I cannot explain this properly.

    What I am trying to say is DISCHARGE THE TUBE.

    I might just confuse here rather than help. The only way I know of is to have the person you are trying to help right next to you.

    I will leave this post here anyway.

    Regards,
    tvtech
     
    Last edited: Mar 27, 2013
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  9. unclejed613

    unclejed613 Well-Known Member

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    how's that..... this board crashed a few months ago, and some pix are still missing
     

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  10. unclejed613

    unclejed613 Well-Known Member

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    and after the TV or monitor is disassembled, short the anode button on the tube to the ground braid that goes around the widening part of the tube. that way, if you don't finish working on the TV/monitor, and it has to sit on the shelf for a few days, the tube won't re-develop a charge. some tubes have a rather large amount of dielectric absorption (cheap glass?, or maybe the chemical composition?), which will cause a new charge on the tube, and a nasty surprise when you go to put the display back together. AMDEK CRT tubes were the worst for this, made even worse by the fact that the anode button was next to the chassis, and to reconnect the anode cap, you had to slide your fingers inside this narrow space, and SNAP! you'd get bit....
     
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  11. tvtech

    tvtech Well-Known Member Most Helpful Member

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    Thanks for adding to my warning unclejed :D

    The next thing I was going to add once the Tube is definitely discharged was this:

    Carefully remove the TV PCB. Take out all the connectors/plugs making a note where they all go.

    Locate the Main Smoothing Cap. It is the one that is rated normally @ between 350VDC to 450VDC and between 100uF to 330uF. The biggest meanest Electrolytic on the board.

    Carefully turn the PCB over so you can see the bottom of the board.

    Take a 5W Resistor of any value from 100R to say 1000R and bend the leads so that you can discharge the Main Smoothing Cap too by simply placing the leads across the Cap. Don't touch the leads...hold the resistor with it's body.

    Hold it there for a few seconds and put it aside....and you are good to go :D.

    You can now work and play and have fun with the Chassis and it will not bite you.

    All you have to do now that it is safe to work on.......is fix it :D:D:D:D:D:D:D

    Regards,
    tvtech
     
    Last edited: Mar 30, 2013
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  12. fezder

    fezder Well-Known Member

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    well this isn't straightly involved to repair but here goes:
    i find it quite confortable to place small power fan next to soldering place/station. reason? no need to hold your breath while soldering, those fumes are not the most healthiest thing to smell.
    i got my head pretty woozy couple times, but i dont have any proper fume extractor. and the air flow doesn't need to be big, just small is enought, and it will not cool your soldering iron.
    and please, get proper lighting....eye ache is a pain in the...right there :D. also, good helping-hand or two, and small lockable scissor type pliers are good also to have. like these:
    http://www.ebay.com/itm/New-5-Strai...553?pt=LH_DefaultDomain_0&hash=item415e10bd31
     
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  13. tvtech

    tvtech Well-Known Member Most Helpful Member

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    Hi fezder

    Like a car runs on Petrol....I run on Solder fumes :)

    I am so used to it.

    Good advise from you though. Just because you seem like a nice person who shares and want's to learn too and does not argue and is generally pleasant all round..+1

    You deserve a little more Rep.

    Regards,
    tvtech
     
    Last edited: Apr 6, 2013
  14. fezder

    fezder Well-Known Member

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    thanks mate for nice comment (and rep too) :). i just simply must use some cind of fume extracting because i have some cind of astma which effects my lungs defensive properties negative way. when i was studying as carpenter, last year school doctor said i should avoid dust....yeah right :D.
     
  15. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    OK, I've mentioned it before - but I'll mention it again.

    A number of years ago I was one of the subjects in a Health & Safety Executive study, in association with a UK University (Sheffield - I think?).

    The study was to determine, for the H&S Executive (so would become UK legislation), if the flux fumes from soldering caused asthma attacks in service engineers.

    The result of the study was that the amount of soldering done by service engineers was no problem whatsoever, but on a production line where you were soldering 8 hours a day fume extraction was deemed necessary and made a legal requirement. In fact the country wide study didn't find a single service engineer who had asthma attacks, they did wonder if they all died or left the trade :D

    But as a result of the study soldering flux was changed - and modern fluxes don't have the possible asthma attack inducing chemicals - but also are a FAR less effective flux.

    Hope this might help you?.
     
  16. fezder

    fezder Well-Known Member

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    hmm, interesting. i dont have asthma but my head starts to ache pretty easily, dunno why, but i see no harm not to breathe fumes :D. but, anyway, nice fact you brought in :).
    my buddy brought me some ''super'' flux, it is designated as toxic, because its toxic enought to melt some materials :S.....havent used it yet on anywere, 2€ cheapo flux suits my needs (yes i'm cheap...)
     
  17. JimB

    JimB Super Moderator Most Helpful Member

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    Be carefull!

    If that flux is not intended for use on electronic components - DON'T USE IT.

    Solder fluxes used for simply joining metals are corrosive and will damage components and wiring.

    JimB
     
  18. fezder

    fezder Well-Known Member

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    hmm, he did mention something using it connecting metals, but he did use it on WERY big wires....but, thanks for info :)
     
  19. fezder

    fezder Well-Known Member

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    Hey, i just remembered another tip, well this isn't straightforward to repair, but here comes, i didn't saw it posted yet:
    what good is soldersucker aka soldabutt, if its completely glogged and fails? a simple test is handy to test soldabutts condition: arm it normally, then suck your own skin with it, press firmly so there is no air gap left. If it still looses its air or completely launches out, you got some work to do. if it doesn't move pretty much at all, your soldabutt is okay.
    what you do when maintaining soldabutt, take it apart, all pieces, clean it, especially o-rings, as they are the key for air-tightness. look at the tip also, if its completely screwed, no wonder if it doesn't suck.
    and, if you really care about o-rings, add small amount (AFTER cleaning them) small amount of vaseline to them. it ensures they are well lubricated as well improves air-tightness.
    And, this maybe was bit stupid tip, but my 2$ cheapo model works FAR better than similar weller one, no joking
    and if you use wick, flux is handy :). if you use non fluxed or cheapo ones....
     
  20. ronnieboy1

    ronnieboy1 New Member

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    any body who has fault on a LG ... 42 LG5020 LCD TV...THIS FAULT WAS ERRATIC LINES AND FLICKERING. check the 24 volt line for ripple .........your find the 1000uf at 35 volts leaky on the power supply.
     
  21. Chipset31

    Chipset31 New Member

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    1. Whenever taking something apart, put the screws back into the threads after you remove whatever they where holding down. That way you won't lose any screws and won't ever have to wonder which screw went where.

    2. After taking the cover/covers off or opening the case of whatever it is you're repairing, take a few pictures with a digital camera/phone for reference later on in case you can't remember how everything fit together or if there's a problem after putting it back together. It helps to take new pictures BEFORE each major step in disassembly.

    3. When dealing with manufacturers or products where almost all the components have custom part number labeling, there's almost always spreadsheets available online that translate the manufacturer specific part number to the real part number.
     
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