How to read these capacitors

Discussion in 'General Electronics Chat' started by magnet18, Oct 28, 2014.

  1. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
    1,232
    124
    first off, guess who just got a sorensen QRD 20-4 power supply for only $20!
    (+/- 25V 5A) (google that for photo)

    Of course it doesn't quite work, being as old as it is I assume it is bad capacitors (same failure mechanism on most old radios)

    I know how to replace caps and blah blah, but some of these on here aren't marked in any code I understand, pics attached, anyone have any ideas?

    (the middle long skinny cap is the one these pictures focused on)

    20141028_202602.jpg 20141028_202615.jpg
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,415
    3,354
    From smallest to largest:

    20μF 12V
    200μF 25V
    1000μF 15V
     
  3. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
    1,232
    124
    Thanks!

    for the smaller ones, the first number is the capacitance in uF?
    How'd you figure that?
     
  4. Lestraveled

    Well-Known Member

    May 19, 2014
    1,957
    1,215
    Congratulations on the new "bench candy", the Sorenson power supply. I have had a QR40-2A since 1980 and I have never had to open the case.

    Also, I concur with Mr.Chips assessment of the value of your caps.
     
  5. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
    1,232
    124
    Thanks!
    Picked it up at the University Surplus store, they also had a 30V 2A and some fluke bench dmms, but this will do for now :)

    Did that used to be a standard naming convention?
    My first thought was voltage range :rolleyes:
     
  6. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    if you check those caps, they are probably ok, those brand and series were made right, not "just for profit" ;ole sp many now.
     
  7. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
    1,232
    124
    Already did, my meter gave me good readings on some of the smaller ones, but some of them are indeed dead

    In any case, capacitors are cheap and I may as well swap em all so I don't have to worry

    It does have a GIANT 4,700 40V "vinylclad" cap, I'm hoping that it is OK, but do those go bad?
     
  8. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,157
    Those vinyl clad capacitors can go bad. In a different application I had a 15,000 uF 600V one have high ESR, which showed up as a ripple on the DC line with a very light load. It was one in a bank of six.

    Here is a typical datasheet.

    I retrieved it from Mouser.

    As far as the other three capacitors, I concur with the others on the value and voltage ratings. It's been many a day since I seen that style. At least you didn't have the dot color coded ones.

    Here's a quick reference for some older capacitors ... http://www.wjoe.com/capacitorinfo.htm
     
  9. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
    1,232
    124
    Thanks Joe!
    I ordered one of those as well, $3 cap with $5 shipping :p

    Still, $20 for the supply and $20 to replace all the caps, I'll have a $100 supply for $40! I'm still happy!
     
Loading...