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Need help identifying capacitors

Discussion in 'Troubleshooting and Repair' started by Subtox, Mar 8, 2016.

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  1. Subtox

    Subtox

    10
    2
    Mar 8, 2016
    Hey guys! This is my first post and I'm an electronics noob so I hope I'm in the right place... I have narrowed down a problem I'm having with my Roland XP-50 synthesizer to a couple of particular capacitors. I know how to solder components but am not an expert by any means so I'm not sure how to identify the new ones I need to purchase.

    The schematic shows "16CV10" below both of these capacitors. Is this enough info to go on, and can someone translate this into the values I'll need to know when buying new ones? Other than this I can say that they are aluminum surface-mount capacitors, but that is about all I know without having them in front of me at the moment (although I will tonight so I can check the codes/markings then if needed). Thanks in advance for any help!
     
  2. 73's de Edd

    73's de Edd

    3,159
    1,329
    Aug 21, 2015
    Will have to research the schema later. . . .but that numbering just shouts . . . .10 microfarads at a 16 Vdc rating.

    73's de Edd
     
  3. davenn

    davenn Moderator

    13,883
    1,966
    Sep 5, 2009
    or possibly 16uF @ 10V ??

    lets see pic's of them on the board
     
  4. 73's de Edd

    73's de Edd

    3,159
    1,329
    Aug 21, 2015
    Still need to know the parts locations on a board (s) . . . . .but after consulting its schematic . . . . .it seems like they have a HIGH proclivity of assigning 6.3, 16 and 25 Vdc ratings for its electrolytics.
     
  5. Subtox

    Subtox

    10
    2
    Mar 8, 2016
    Thanks for the replies. See the attached photo -- now that I actually see them on the board it's apparent they're 16V as they are both marked as

    51
    10
    16V

    But I'm still pretty clueless haha, so do you have any recommendations for replacements?

    On a side note, what are your thoughts on replacing this whole cluster while I'm in there -- i.e. do they tend to go bad together? (This is a 20 year old synth if that matters.) I read from some other users at a Roland forum that they replaced every cap on that board and when they got to C174/5 this issue was fixed; although any of those they had already replaced might have been bad as well.
     

    Attached Files:

  6. davenn

    davenn Moderator

    13,883
    1,966
    Sep 5, 2009
    Yup as Edd said, 10uF 16V,
    I see a couple of 47 uF ones there as well

    so is there any particular reason why you think the caps are faulty and not some other component ?


    Dave
     
  7. Subtox

    Subtox

    10
    2
    Mar 8, 2016
    Honestly I had no idea what it could be until I found this discussion:
    http://forums.rolandclan.com/viewtopic.php?t=42164

    Here are the comments that led me to start with C174/175 (and possibly C921/922):

    I just did this as well and I think you may be correct that 921 & 922 are the culprits. I replaced a few caps, tested, replaced a few more, etc. It wasn't until I did 921 & 922 and two others that the hissing problem was resolved.

    ~~~~~~~~

    Replaced C922 and C921 as suggested but problem persisted. Not wishing to replace all the caps, I checked the circuit diagram, and because the problem was left channel only, I identified all the relevant caps, C11, C8, C175 and C93. I then replaced and tested, and when I got to C175, the problem disappeared. (C174 is the corresponding right channel cap)
     
    davenn likes this.
  8. hevans1944

    hevans1944 Hop - AC8NS

    4,626
    2,159
    Jun 21, 2012
    Twenty years is really pushing it for elecrolytic capacitors. The electrolyte paste slowly dries out over the years. Many techs replace all the electrolytic capacitors on equipment this old because the cost of troubleshooting exceeds the cost of the components. And if some haven't failed yet it is just a matter of time until they do. Thank God intergrated circuits last forever... mostly.
     
    davenn likes this.
  9. Subtox

    Subtox

    10
    2
    Mar 8, 2016
    Thanks, hevans. I might go that route to just nip it in the bud. I'll need to buy them singly since I don't have a supply on hand but it'll probably be less of a headache in the long run.

    By the way, can anyone explain the top number ("51") on these caps and whether it even matters as far as purchasing a replacement? I can't seem to find any info about this coding scheme, only the 3-digit industry codes.

    Browsing electronics supply sites I'm seeing a lot of parameters such as tolerance, ripple, polar/bipolar, impedance, etc. that I'm not sure about. I realize I can't ask for a full electronics course here, but are there certain parameters that are optional and others that are imperative for this type of application?

    Lastly, any brand recommendations? I don't have much to spend but don't want them frying on me again (that eternal struggle of price/quality). I hear good things about Rubycon, Sanyo and some others.
     
  10. 73's de Edd

    73's de Edd

    3,159
    1,329
    Aug 21, 2015
    .


    Sir Subtox . . . . . . .

    Thank goodness you gave us that photo, as some of those particular types are the very-very-very worse that I have ever seen in surface mount electrolytics.
    They have a high failure rate in their leaking out their electrolyte blend of caustic salts mixed with a wet electrolyte carrier of dimethylformamide.
    If leaked out it is conductive across a foil path,highly corrosive and also hygroscopic.
    With time it leaves a VERY black stain on the board beyond compare, I have had no success with use of Xylene, Toluene, De ionized water, MEK or Acetone or a witches blend of all in removing that staining.
    BUT the THOROUGH scrubbing DID leave the board void of any conductive agents, thus being able to replace the caps with conventional radial leaded ones with micro L bends at their soldered ends.
    Check VEWY-VEWY closely around them for black staining and that stain can even go / penetrate through to the opposite side of the board.

    Your unit seems to be circa 94-96 and I can see them both in coupling and bypass functions around that D63200 DA-converter chip.
    I had serious problems with them back as far as the 90's when I ended up replacing 14 of them in a Mistsubishi BIG Screen television of mine.
    They were in the Picture-in picture video section and were causing vertical jitter and roll along with progressively darker video, plus no pic in pic..
    Later a full sized VHS RCA Camcorder of mine, required approximately 22 of them to be replaced.
    With so many to be replaced I evolved a special procedure for pulling them with no board damage, you just don't attack them from the top down with a soldering iron tip.
    Encountering soooooooooo many units, I even made a special cap removal tool from a pair of reground $1.00 needlenose plier / cutters.

    Report your findings and . . . . . . . What problem / effect is that unit giving ?


    73's de Edd

    .
     
    Last edited: Mar 12, 2016
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