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Identifying non-electrolytic capacitors?

Discussion in 'Electronic Repair' started by anamouse, Nov 1, 2003.

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  1. anamouse

    anamouse Guest

    Can someone help me identify these capacitors?

    I have posted pictures of them here:
    http://www.home.earthlink.net/~circuitrepair/capacitors.html

    These are on the tonal board of a 1974 Capehart stereo. The bass has always
    been a bit distrorted, more so when the bass is turned up. It's not very bad,
    but annoying enough.


    My questions are, what type of capacitors are these, and how do I identify what
    their ratings are?

    What is the difference between the orange types shown, and the green ones
    shown?

    What I could find, I think K and M are supposed to mean their tolerance. With K
    = 10% and M = 20%. Is this correct?

    For the ones with the minus or dash symbol inside a circle, does the minus/dash
    mean something? What about the letters of R (C1,2) and N (C11,12)?

    The parts have the following information on them:

    C1, C2: 473M
    100 - R (the minus sign is inside a circle, as shown in the
    pictures) These are orange capacitors.

    C3, C4: .015
    100 (?) Not sure what the (?) is. I think on one it looks like a
    7 but I could be wrong. These are green capacitors.

    C5, C6: 222K These are orange capacitors.

    C7,C8: I wasn't able to access these. These are also orange capacitors and look
    similar in size to C5, C6.

    C9,C10: 50V - 1K These are green capacitors, fatter then C3, C4.

    C11,C12: 223M
    50 - N These are orange capacitors, with the minus or dash
    sign inside a circle, as shown in the pictures.

    Thanks for all who can help me deciper and understand the code!
     
  2. Ian Barr

    Ian Barr Guest

    C1, C2 0.047uF or 47000pF 100v (uF=microfarad pF=picofarad)

    C3, C4 0.015uF or 15000pF 100v

    C5, C6 2200pF no voltage shown probably 50v or 100v

    C7, C8 ?? ??

    C9, C10 0.001uF or 1000pF 50V

    C11, C12 0.022uF or 22000pF 50V

    The letters are indeed the tolerances - just use 5% replacement and you
    won't go wrong.

    Whether this fixes your problem is another matter.
     
  3. anamouse () wrote:
    : Can someone help me identify these capacitors?

    : Thanks for all who can help me deciper and understand the code!

    Although I hate to point out when someone is on the wrong track, you are on
    the wrong track.

    These capacitors, in my opinion, will probably out live you and your
    children, possibly grandchildren. These are all mylar caps probably seeing
    an audio level signal around 500mv at best. Although anything can happen to
    a device, it's not likely any of these are bad or went bad through the
    years.

    Being the "Capehart" name, is probably more likely one of them is the wrong
    value which was put in at the factory. Your problem, if I read it right was
    something happening to the bass when the volume went up. That is a pretty
    open wide complaint, likely to be a transistor or electrolytic cap in the
    audio amplifier section. At least that is where I would start poking around.

    Anyway, as far as reading the caps, generally anything marked 25, 50 or 100
    (with or without the v after it) is going to be the max operating voltage.
    It's not likely to be of much importance in this case. General rule of thumb
    if you are going to replace any or all of them is equal or greater is fine.
    So if you run into a 104k 50v and can only find a 104k 100v, go for it.
    Won't make any difference.

    I also wouldn't worry about the R's N's, those probably are tolerences and
    would have little to no effect if a better grade was found. At least in this
    application. Again, general rule of thumb.

    The numbers before the K's and M's are the values, along with some written
    out (in the picture with the orange 222k's the greens appear to be .015 or
    ..045). I've seen the "rule of conversion" argued before because there are
    exceptions to this scheme, but the general rule of thumb with these is that
    the first 2 numbers are the value with the 3rd being how many zeros to use
    with the value. The arguement is what you do with the zeroes.

    Anyway, this would be a limited conversion...

    marked 221 would be 220pf
    marked 222 would be 2200pf or .0022uf
    marked 223 would be .022uf (i don't consider 22000pf a real value)
    marked 224 would be .22uf

    Anything larger (225) would more likely be an electrolytic and marked
    longhand (2.2uf).

    Just switch the first two digits with the above for the others, one marked
    473 is the same as 223, just 47 instead of 22, so that would be .047uf. Only
    point of confusion are the 10's, but is the same (102 is .001 or 1000pf, 103
    would be .01, 104 is a .1, 105 would be 1.0uf).

    But being the difficulty in replacing these and my original point about
    being on the wrong track, might be a good excerise in soldering if you
    wanted to replace all of these (along with a lesson about working in close
    quarters (good luck finding dial string these days)), it just isn't going to
    fix anything.

    -bruce
     

  4. What makes you think these capacitors are the source of your problem?

    I'd be looking in the power amp section, or maybe the power supply.
     
  5. anamouse

    anamouse Guest

    Was Capehart known for putting wrong values into their radios?
    I have changed all electrolytic capacitors on the main board, as well as the
    resistors (they were the carbon composition type). The sound quality remains
    the same as before the recap/re-resistor job. I have not changed anything on
    the tonal sub-board, but plan on replacing the carbon composition resistors.

    BTW, there was a bad transistor for the right channel of audio that was
    creating crackling sound. I was able to find which was bad by spraying freeze
    spray on each transistor until I found the bad one. Replaced it as well, and no
    more crackle.

    What is happening, is that the sound is a bit too bassy even with the bass
    control all the way down. Once I start adjusting the bass control up, the bass
    sound creates a muffled almost distorted sound. Since the caps and resistors
    have been replaced on the main circuit board already, I thought the problem
    could be on the tonal sub-board.


    Thank's much for the explanation on how to read the numbers on the capacitors,
    as well as letting me know they are mylar.
     
  6. anamouse

    anamouse Guest

    Laurence, I have already replaced all the electrolytic capacitors, as well as
    the carbon composition resistors, on the main circuit board. I originally did
    this because of the age of the radio. The sound quality was the same before the
    recap, though, so I am sure the recap did not introduce the bass problem.
     
  7. anamouse

    anamouse Guest

    Ian, thank's for posting the values!

    I'm still wondering though, what is the difference between the orange types
    shown, and the green ones shown?
     
  8. Jeff

    Jeff Guest

    I would like to think I know what I am doing BUT I
    keep saying things that I have done that make no sense.
    ITS a CAPEHART unit! troubleshoot it to the problem
    or give it to someone who can.(If it has one)
    NEW it had poor sound quality OLD and used I would
    expect it to be worse.
    Changing every single part in it may fix it or it may not!
    Pick an area and start changing resistors and or capacitors is not a method
    of repair or troubleshooting
    it is barely even educated guesswork as you have applied
    it.
    Is the load (the speakers) the same it was designed for?
    Like 10W max.(maybe 20W) @ 8 ohm.
    Are you exceeding its rated output?
    Have you made any measurements at all?
    Have you any published specs on the unit?
    Have you tried bypassing the tone controls?
    Anything that makes any sense at all?
    And not a mention of a model number in case someone
    on this group may have a schematic on it.(like SAMS)
    Jeff
     
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