Broke electrolytic capacitor

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Re: Broke electrolytic capacitor

Postby jason1 » Thu Mar 08, 2012 8:14 am

Oh my, I am taking up way too much of your time. I added two pics to show how I set up checking for current. I got a reading of ?. Can't remember how to read this thing. Too early, pulled out boost converter, reinstalled, looks OK. Also, Found some gunk near a resistor under my blue electrolytic capacitor, old superglue, cleaned up. Can't figure out why there is current, no solder joints on the bottom are touching, everything on the top looks OK. Could it be the blue capacitor?

So I cleaned up the solders again, checked voltage, 5V, then felt boost converter, not hot, then checked current again, 0.15A

Thank you,

Jason1
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Re: Broke electrolytic capacitor

Postby adafruit_support_bill » Thu Mar 08, 2012 11:59 am

Hmmm. You've got either 7 or 14 of something. :) Do we know what units we are looking at?

I wouldn't expect 7 or 14 mA to make anything terribly warm.
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Re: Broke electrolytic capacitor

Postby jason1 » Thu Mar 08, 2012 12:06 pm

Well, I borrowed this, but I think the way it is set up it runs on four different levels 100uA 100mA 1A and 5A. I hooked it up to 1A, so I figure each hash is worth one. Regardless, after I cleaned it up I put it back together, waited about 15 minutes, by now it is pretty hot to the touch. I'm going to let it go until I get a sizzle. Maybe I could just install a cheap switch?
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Re: Broke electrolytic capacitor

Postby adafruit_support_bill » Thu Mar 08, 2012 12:22 pm

I'm guessing that means that 1A is full scale, which would mean you are burning 140mA with no load. Are any other components getting warm?
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Re: Broke electrolytic capacitor

Postby jason1 » Thu Mar 08, 2012 12:23 pm

No, just the boost converter.
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Re: Broke electrolytic capacitor

Postby adafruit_support_bill » Thu Mar 08, 2012 2:14 pm

Not sure what is going on there. One possibility is that with the solder re-work, some of the flux residue has become burnt enough that it is conductive.
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Re: Broke electrolytic capacitor

Postby jason1 » Thu Mar 08, 2012 4:25 pm

So, how do I fix?
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Re: Broke electrolytic capacitor

Postby adafruit_support_bill » Thu Mar 08, 2012 4:50 pm

Some gentle scraping with the tip of a knife and/or scrubbing with isopropyl (90+%) usually do the job.
Don't bother with the 70% isopropyl. It just spreads it around and makes everything sticky.
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Re: Broke electrolytic capacitor

Postby jason1 » Thu Mar 08, 2012 8:39 pm

No go. Nothing seems to stop the current flow. Bummer. Kills the battery pretty quickly. I'll fool with it a bit longer, but after that it'll go in a drawer for a while. Maybe buy another down the road. Thanks for your help. Jason
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Re: Broke electrolytic capacitor

Postby jason1 » Mon Mar 12, 2012 10:48 am

Did all the cleaning and scraping I could think of, can't get it to cool down if batteries are installed. I decided to add it to an Altoids case and see if the case would remain cool, but it gets hot to the touch. Unfortunately, I am not going to order kits for my team as this build was to test viability.

Take care,

Jason1
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Re: Broke electrolytic capacitor

Postby adafruit » Wed Mar 14, 2012 12:37 pm

this is without it attached to anything?
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Re: Broke electrolytic capacitor

Postby jason1 » Wed Mar 14, 2012 12:55 pm

Yes. Just batteries, no cell phone charged.
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Re: Broke electrolytic capacitor

Postby adafruit » Wed Mar 14, 2012 1:22 pm

can you post another really clear photo of the top and bottom? it sounds like something is shorted out - do you have someone around you who is experienced with soldering?
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Re: Broke electrolytic capacitor

Postby jason1 » Wed Mar 14, 2012 1:30 pm

OK. Here are more pics. Nope on the soldering.
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Re: Broke electrolytic capacitor

Postby jason1 » Wed Mar 14, 2012 1:32 pm

two more pics
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