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Non Polar / Polar capacitors

Discussion in 'Car Stereo Amplifiers' started by Fbmowner, Oct 18, 2010.

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  1. Fbmowner

    Fbmowner Full Member

    Maybe a few of you remember my post a while back. A cap in my amp went bad and i went nuts looking for a new one. After ordering one and it being on backorder for over 2 weeks , i just recently canceled the order and got a different one from another site.. After reading up on caps in a catalog i got from mouser i realized that the capacitor in my amp was an aluminum electrolytic NON polar cap.. The one i order is indeed polar but the same uf, volt and temp ratings as the one thats in the amp. I bought 5 of these caps incase i ran into some problems, so my question is, Is it okay to use a polarized cap inplace of a non polar cap? From what i understand if you have the polarity backwards on the cap it will pretty much overload and go pop.. Good thing i bought 5 rite?

    P.S. Id also like to mention that i cannot find a non polar aluminum electrolytic cap thats at least 200volts with a 10uf rating.. im fixed on getting an aluminum elec. cap because i want the size of the new cap to be the same as the old one.
     
    Last edited: Oct 18, 2010
    Fbmowner, Oct 18, 2010
    #1
  2. TheViking

    TheViking Well-Known Member

    Is the cap replacing one that is in the power supply or in the finals of the amp? It shouldnt matter, but If I remember correctly, ( and someone correct me if i am wrong) if its in the power supplies AC section, it will matter. One side note....you CAN go with a higher voltage cap...as long as the uF rating stays the same...
     
    TheViking, Oct 18, 2010
    #2
  3. Fbmowner

    Fbmowner Full Member

    Its located directly behind the speaker output terminals and is the only one in that area. All the other caps on the board are polarized and in the middle or directly behind the power and ground inputs on the board. I cant find any non polars that go up to 200v. If i could find higher with the same uf rating id get em. Its like this one cap is the one cap from hell.. i even called harman and they dont supply the part anymore.
     
    Last edited: Oct 18, 2010
    Fbmowner, Oct 18, 2010
    #3
  4. TheViking

    TheViking Well-Known Member

    then go with it I say. power the amp up and using a VOM check for which side of the the board is positive and negative and install cap accordingly.....I honestly dont see it ever hurting anything myself.....A cap is a cap generally speaking. Foil and wax paper...with some "goo" in it at times! As long as the voltage rating is as high as the original, you will not smoke it. But the thing to remember is this, there may be a reason why the original blew...bad transistor, a resistor that has gone low, etc...
     
    TheViking, Oct 18, 2010
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  5. Fbmowner

    Fbmowner Full Member

    Im going with old age and abuse =D .
     
    Fbmowner, Oct 18, 2010
    #5
  6. TheViking

    TheViking Well-Known Member

    let me know how big the explosion is when your done! LOL!
     
    TheViking, Oct 18, 2010
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  7. Fbmowner

    Fbmowner Full Member

    haha sure will, ill most likely be recording it while i power it up.. One more question for ya tho.. Is it okay to power the board up while its out of the case/heatsinks just to get the polarity on the board. There was also a ground wire on the board that went to the amp case..will i have to worry about grounding that to power it up while its on the bench?
     
    Fbmowner, Oct 18, 2010
    #7
  8. ericj

    ericj Full Member

    Absolutely DO NOT power it up without the heatsinks! You'll blow the output transistors before you're able to say FU*K!

    You can power it with very low voltage, but there's a huge risk you'll destroy the OTs. I wouldn't risk it. Follow the PCB traces or post some pics here and we'll help you determine polarity.
     
    ericj, Oct 18, 2010
    #8
  9. Fbmowner

    Fbmowner Full Member

    Fbmowner, Oct 18, 2010
    #9
  10. ericj

    ericj Full Member

    What part are you trying to get the polarity on? The caps should have a big black or grey stripe on the negative side.
     
    ericj, Oct 18, 2010
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  11. Fbmowner

    Fbmowner Full Member

    As i said in first post.. The cap that was there was non polar.. I cannot find a non polar cap thats 200v 10uf which is also aluminum electrolytic. So im wondering if i can just use a polarized cap , but id like to determine which side is + and - on the board
     
    Fbmowner, Oct 18, 2010
    #11
  12. ericj

    ericj Full Member

    It's hard to be 100% sure from the photos, but I think you could probably test it with a DMM on the continuity setting. Touch one lead to a known ground and the other to each side of what's left of your capacitor. This should tell you which side is ground & which is positive.

    Of course, the other option is to reconnect the heatsink again and power it up to check it.
     
    Last edited: Oct 19, 2010
    ericj, Oct 19, 2010
    #12
  13. Fbmowner

    Fbmowner Full Member

    Thanks for the idea. I did this today and got a continuity reading from one lead from the cap to the negative speaker terminal output. The one thing im concerned about is since i got a continuty reading between one side of the cap and the negative speaker outputs, this means its oviously in line with the speaker outputs, and isnt that AC ? Resulting in blowing up the polarized cap?
     
    Last edited: Oct 19, 2010
    Fbmowner, Oct 19, 2010
    #13
  14. TheViking

    TheViking Well-Known Member

    Some amps reference the audio outputs to ground. I believe the old orions left negative and right positive would show to ground if i remember right.
     
    TheViking, Oct 19, 2010
    #14
  15. Fbmowner

    Fbmowner Full Member

    Heh? lol... If this helps at all to my confusion here, One side of the cap meaning one solder point had continuity to both of the negative speaker output terminals.
     
    Fbmowner, Oct 19, 2010
    #15
  16. TheViking

    TheViking Well-Known Member

    looked at a feew of the pics, not sure which cap you were indicating...would it be too much trouble for you to take and circle or mark the cap you wanna replace then post it? That may help me out a bit!
     
    TheViking, Oct 19, 2010
    #16
  17. Fbmowner

    Fbmowner Full Member

    Sure! http://yfrog.com/5tcaphjj " heres the actual cap and label http://yfrog.com/nblabelhj
     
    Last edited: Oct 19, 2010
    Fbmowner, Oct 19, 2010
    #17
  18. ericj

    ericj Full Member

    Have you tried testing continuity from a known ground, like one of the other caps, one of the big solder blobs, or the ground strap you mentioned in an earlier post?
     
    ericj, Oct 19, 2010
    #18
  19. TheViking

    TheViking Well-Known Member

    OK! Now I see it!

    Measure, with your meter, on each lead in the cap to the ground wire of the amp...the one that shows 0 ohms is the side the negative goes on. If you get it backwards, no harm should come....just solder the darned thing in and put it back together!
     
    TheViking, Oct 19, 2010
    #19
  20. ericj

    ericj Full Member

    ericj, Oct 19, 2010
    #20
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