esr tester which to buy any ideas

Discussion in 'General Electronics Chat' started by diesalweasel, Sep 13, 2010.

  1. diesalweasel

    Thread Starter New Member

    Aug 28, 2010
    21
    0
    i everybody i'm new to this site.
    i need some help i'm trying to locate an esr tester to basicly test if the cap is good or bad in circuit (in circuit tester)
    anyway i found a couple on ebay and it ranges from i think 0.01uf can you get lower than this i got told pf was the lowest

    if pf is the lowest i fink nf is the next and the uf and so on i fink please correct me if i'm wrong.

    what it is i repair laptop computers as a hobbie
    and i need something what can test

    smd ceramic caps
    smd eletrolitic caps
    smd tantalum caps
    and finealy the old eletrolitic caps

    is there such a device rooled in to one

    on ebay the esr meter thay only state thay do capacitors it doesent say if thay support smd i have asked a some people are ignarent.

    and the reason i asked about if there is one what does from pf upwards is that on some of the smd ceramic caps there no markings on them

    any help would be greatful

    from jamie
     
  2. electronis whiz

    Well-Known Member

    Jul 29, 2010
    519
    27
    take a look at this vom this is one i have been looking at for when my current one dies. http://www.multimeterwarehouse.com/DT9205f.htm
    if this is not it try a ggogle shoping sherch for voms. if you want add in that feature too.
     
  3. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    It's very difficult to test most components "in circuit" unless you've got some rather expensive equipment and even then there are a lot of limitations. You pretty much have to have a schematic, formulas and a calculator in hand to interpret the results and some things can't be tested at all.
     
  4. diesalweasel

    Thread Starter New Member

    Aug 28, 2010
    21
    0
    i there to all ansered my post. i thing i may of found one. i rang up peak electronic who make the esr plus 70 meter here the link http://www.peakelec.co.uk/acatalog/jz_esr70.html any way had a good chat with the tech. it does the 4 component i need it for which is great .
    he also so said pf and nf never realy go down it usaly big component so i can undersstand. like uf that why people build esr meter probaley start from uf as the other are not worth bothering with for a guess
    ps sorry about my spelling mistakes i'm not that good at writeing
    ps i forgot to tell you in my first post i'm not all that experienced with electronic i was tired last night. if anything i will put my hand up and say i'm a newbie. i know bits i know how to do the odd thing on circuit boards.
     
  5. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    True, and computer manufacturers have a long history of using the cheapest electrolytics they can find then expecting them to last in areas that have a lot of heat around them.

    Always suspect and preferrably replace any electrolytic that shows signs of:
    1) any leakage (but don't be fooled by the fact they sometimes glue them down)
    2) any bulging of the case, usually the top starts to get a bit rounded outwards
    3) any which the label has started to visibly shrink on

    Tantalums often give themselves away by exploding or cracking in half but sometimes they do just short.
     
  6. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
    141
    No need to apologize, most folks can probably infer your intentions, but it's less work for the reader if the spelling is mostly correct. If you want to make it easier on yourself, use a browser like Firefox and turn on spell checking. Then it underlines with a wavy red line any misspelled words in your post, giving you a chance to correct them before posting (just right click on the underlined word and you'll get a list of possible word choices, then pick the one you want to substitute).

    Now, on to the original question. Measuring ESR is a handy technique for finding bad capacitors, but it's usually only used on electrolytics of substantial capacitance (say, on the order of above 10 μF or so). If you have a scope and a function generator, you can make useful ESR measurements with them (there are a number of web pages devoted to this topic). The Peak Electronics unit looks like an excellent unit with good documentation; the only things I don't like about it are a somewhat non-standard battery and that it only tests at 100 kHz. More expensive ESR meters give you a choice of frequencies; for example, the B&K 886 will let you use 0.1, 0.12, 1, 10, or 100 kHz test frequencies. You'd typically use the 100 or 120 Hz test frequencies for capacitors used in an AC line-based power supply. Of course, I realize that an instrument like the B&K 886 is probably priced out of the range of the average hobbyist.

    Expanding on what marshallf3 said, trying to measure capacitances with nF and pF values in-circuit is going to be difficult to impossible because you'd really be measuring the combined capacitance of everything in parallel with that capacitor (and an ESR measurement in such a situation has little meaning). The only sure way is to remove one leg of the device and then measure; this is problematic with surface mount stuff of course.
     
  7. diesalweasel

    Thread Starter New Member

    Aug 28, 2010
    21
    0
    i think the b&k 886 is little out my price range lol .i don't have a scope or function generator only have dmm lol are you talking about a wave scope is that the one what got a mic connected to i thing it called a Oscilloscope is that the same thing or diffrent ?
     
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