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What was going to be a A Hack of Day — Parallax Forums

What was going to be a A Hack of Day

sam_sam_samsam_sam_sam Posts: 2,286
edited 2010-10-27 11:12 in General Discussion
Turn out to be a Repair of The Day

Start early in the morning Today My Out Door Camera DVD Recorder and LCD monitor was not working right

The picture on the LCD screen was rolling up the screen real,real fast and was not looking good could not SEE anything worth while on it

I took a CTR monitor and hook it to the Out Door Camera DVD Recorder
WhaaaaAaaa there is four pictures from all of the outside Cameras now showing on the screen Ype YPE ya A

So I said well a new 13" LCD Monitor is about $200 and on the back of this monitor say no user part are inside I though well this monitor is trash any way so let see what part can be found It took a little doing to get the back off of it and what do you think I saw when I when did get it apart

I found two CAP that had there top pop up so I look in my cap bucket found one that was the right value and for the other cap I had to put two of them together and guess what when I put it all back together and power it on it start working again I am so happy that I do not have to buy a new 13" LCD Monitor right now I do not have a job right now again

All four switching power supply for the Camera the power output caps have done the same thing I just replace them with new one and the start working again These cap must be REAL CHEEP this hole system is about two years old

I just thought I would share this with you people on the forum

So if your computer LCD Monitor start acting stupid take it apart first and see if any of the caps have pop there tops if so replace them and power it back up and see what happen

I also do this with CFL light bulbs (20 watts or more )some time it just the bulb and some times it the circuit board is the problem

If you try this with CFL light bulb less than (20 watts ) this it a little hard to get them apart with out breaking them

I can do this with the Yard Light that I have because I buy the same brand for all of them

I have more time than money and I want use them as much as I can

The repair of the day Thanks for reading this post

Comments

  • icepuckicepuck Posts: 466
    edited 2010-10-25 17:59
    And fixing it keeps it out of the landfill.
  • sam_sam_samsam_sam_sam Posts: 2,286
    edited 2010-10-25 18:07
    That so true how ever I would have parted it out first before I send it on it way to the land fill

    Funny thing where I live is when you put like a tv or an LCD tv or mointer at the street when you come back a few hour later it gone so I do not know if it make it to the land fill or not
  • Peter KG6LSEPeter KG6LSE Posts: 1,383
    edited 2010-10-26 06:58
    Sam did the caps look like this ?
    3831347382_68826689c2.jpg


    Peter
  • sam_sam_samsam_sam_sam Posts: 2,286
    edited 2010-10-26 08:03
    Dose your monitor work now or is it dead

    If your monitor is not working right what is it doing Please explain

    Yes it dose in fact both board look almost the same

    The top of the one caps look like it is pop up and not flat

    Also the boards look very much the same as the one that you are showing and look like the same one that pop up on mine

    From your photo it look like one of them for sure look bad and other one look bad but it hard to tell on the other cap from the photo

    If you have a cap tester you will know if its good or not
    Be careful when removing these cap that you do not break the traces on the board on one of mine I tore a little of one side of the trace off the board
    And that use a cap that is rated the voltage or higher and that the values are the same as the one that are there and MAKE SURE that you put the + and - where they should be

    One cap that was 1000uf @ 10 volt
    One cap that was 680uf @ 16 volts this one I had to put two 330uf @ 25 volts which work


    attachment.php?attachmentid=74705&stc=1&thumb=1&d=1288107272
    600 x 450 - 60K
  • skylightskylight Posts: 1,915
    edited 2010-10-26 12:54
    good to hear, bet your'e a happy cappy I mean chappy :smilewinkgrin:
  • Peter KG6LSEPeter KG6LSE Posts: 1,383
    edited 2010-10-26 14:00
    Ill shed some light on why I think this happens.

    First I saw they used 35V caps on the 12V rail . 0.0 OVER KILL.
    its a SMPS the V ripple swing is not that bad.
    a 16 or MABY a 25 would do .

    but I got thinking . HMM SMPS its HF 40 KHz or more . not a mesliy 60Hz . so IF there is Ripple its Charging and discharging a boat load more often then in a Iron core anchor supply .

    and I thought of My experience with Hi current and HF with tesla coils ..
    the rolled caps some use are VERY lossy and can over heat and explode .
    this is because of inductive losses . and losses dont just go away like magic , no,they HEAT up parts like mad .
    now the SMPS for that Computer screen were 105C Hi Temps . but ill bet thatt local temps inside that cap can were more then that in some parts of the cap .

    the ESL / ESR of normal Electrolytic caps is so horrid in comparasion to a normal Mica or ceramic cap.

    Taintms are Much better then Electrolytic BUT there expensive .

    there are Hi Ripple Electrolytic caps out there , Photo flash aer a common use for them . but lets face it . most companys are CHEAP
    . BTW that photo was form a Top of the line View Sonic .

    they would rather bet on you the consumer on upgrading and tossing the old one then spend $10 more on better caps .

    I Proved My theroy By useinf a Current O-Scope probe and scoping the GND side of the 5V rail cap. I observed 20-30 A peaks at times . now I know there peaks not RMS but it shows that Some SMPS's are High Ripple current on the inside .
    you put 20A in and out of a lossy cap and you'll get heat ..
    not to mention the dielectric is not happy with KHz of relative deep discharges ..

    Oh about that board . I used the right caps to fix it and tested it and its bean on now for a year at my desk in lab .

    BTW putting 2 smaller caps in parallel is a simple way to reduce ESL and ESR but is a circuit desgine night mare . NOTE.. lots of computer MoBo's are done with a array of caps in || of each other . In the Tesla world it callled a MMC array .

    what you did IF it fits in the case is not a bad idea ! provided the 2or more caps are matched ( manufacture and model)
    Peter
  • sam_sam_samsam_sam_sam Posts: 2,286
    edited 2010-10-26 14:38
    Thank you for explaining what you found

    In fact when I have some money to spend i was think of getting real good battery back up the one that have a real sine wave output when it is on battery power for the Out Door Camera DVD Recorder and LCD Monitor to help this from doing this again

    Yes the two cap where match and they where the only two that I had of that value
    I had a lot of room for the one but the other cap there was just enough room for the one cap and that was it

    But where I live we have add problem we have brown out, voltage jump, voltage dips and it seem like it happen all the time
    and more so in the summer when everyone is running the A/C in the winter it is not so bad
    it was a lot worst before I add a capacitor bank to the hole house

    If fact it was so bad that if the refrigerator came on the lights would dim if the A/C came on the lights just about off for 1/2 a second
    then right back up the same thing with the pool pump same thing with the freezer at one time I had two freezer running

    One note not all of the cap are 105 *C some where 85* C and I only have ones that where marked 85* C

    If it goes out again I will change all of them to 105*C

    What brand of caps should I get when I replaced them
  • Peter KG6LSEPeter KG6LSE Posts: 1,383
    edited 2010-10-26 16:13
    Brand is not factor relly .. chemcon robycon are all good names but look for LOW ESL or LOW ESR caps . all other things being equal should help with the" busting a cap " issue .

    as for V Sags On the Input to the SMPS . Most I see are as wide as a barn door when it comes to inputs . a decent SMPS can do 90-260 V or so input @ 40-70 Hz . I have yet to have a brown out on a SMPS in Years .

    Peter
  • lardomlardom Posts: 1,659
    edited 2010-10-27 08:32
    I spent about $500 about a year ago to get my computer repaired. The motherboard failed because of bad electrolytic caps. I kept the board so I could study it. From now on I will 'look' and 'sniff' for the obvious component failure.
  • lardomlardom Posts: 1,659
    edited 2010-10-27 08:46
    Peter, I always regarded "busting a cap" as a street phrase used by gang members with pistols. Sort of like "I'll bust a cap in your (posterior)!
  • Peter KG6LSEPeter KG6LSE Posts: 1,383
    edited 2010-10-27 09:41
    Lardom that was the pun :)

    Iam goina to bust a 220µF 400V cap on ya !

    on a more serious note I have seen blown caps do some serious damage to boards .
    and one time a kid in my e tech lab class RPed a tantalum cap and it like a 22 put a Hole in the celing tiles ..
  • lardomlardom Posts: 1,659
    edited 2010-10-27 11:12
    Peter, I don't want to go off topic but Ron Czapala posted a video with a father and young son launching a high altitude ballon which took HD video of near space. They retrieved ithe camera 30 miles from the launch site. I thought it was pretty amazing.
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