Blown Bugle PS Decoupling Cap

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pjanda1

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Blown Bugle PS Decoupling Cap
« on: 26 Mar 2008, 05:55 pm »
I just got a pair of SLAs (B.B. Battery 1.2 Ah's from Digikey).  I put a 9V connector on each one.  About 1 sec after I connected the first one, the 220uf (PS decoupling, right?) blew.  Was it just a fluke?  The 16V doesn't leave too much leeway.  My MM batts are charging, but I wouldn't be surprised if the 12V SLA is 13.5V unloaded.  I think I've got an extra cap, but how likely is it that this will happen again?  Should I trot down to Radio Shack and buy their 35V 220uf electrolytics?  Any opinions on their quality?

I searched a bit, and it doesn't look like other folks have had problems with SLAs and the stock cap.  I know I could just try it again and see, but I hate to do too much as my desoldering skills (and equipment) aren't incredible and I've damaged PCB pads before.

pj


hagtech

Re: Blown Bugle PS Decoupling Cap
« Reply #1 on: 26 Mar 2008, 11:33 pm »
You just wired the negative supply with wrong polarity.

jh

pjanda1

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Re: Blown Bugle PS Decoupling Cap
« Reply #2 on: 27 Mar 2008, 02:31 pm »
I see what I did.  A horribly stupid mistake; I wasn't thinking.  I was using 9V battery clips to hook the batts to the Bugle.  I just wired the red wire to the positive terminal on the battery and - to black.  It hadn't occurred to me that I'd be using the clip opposite the way it was intended (on the battery side) so the polarity would be reversed.  Hopefully others will now avoid the same mistake.

thanks,

pj


ChairSpud

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Re: Blown Bugle PS Decoupling Cap
« Reply #3 on: 5 Apr 2008, 01:43 pm »
You're not alone, I made the same "stupid" mistake using 9V battery clips.