circuit board electrolic cap

[jjd35]

I just finished testing my boards and everything seems to work fine, but I just released that I soldered the electrolic cap with the minus sign to the left instead of the right does this make a difference or will It be fine the way it is thanks

[JBullard]

jjd35 wrote:

I just finished testing my boards and everything seems to work fine, but I just released that I soldered the electrolic cap with the minus sign to the left instead of the right does this make a difference or will It be fine the way it is thanks

An electrolic capacitor is polarity dependendent. It must be installed correctly

[ErnieHorning]

Definitely turn it around. Backward capacitors have a tendency to explode making you less than happy.

[Guest guest]

ErnieHorning wrote:

Definitely turn it around. Backward capacitors have a tendency to explode making you less than happy.

Amen.

You say it is working?

Have never seen a schematic for the unit, but am somewhat surprised it is functional. All channels, fully functional? (No, do not power it back up to answer that question!)

But..if you definitely put it in backwards, switch it around. To be safe, remove it and replace with a new one. Gut says you'll be ok just turning it around.

Also check to make sure you put the other electrolytic in properly also.

[ErnieHorning]

It's probably in the power supply. I've seen capacitors work equally well backward. In backwards, it has some resistance which will generate heat. Over time, and this will be variable, pressure will build up inside. The top has partial cuts in the aluminium cover which will initially bulge and split releasing the pressure. If it's not bulging at all, I wouldn't have a problem reusing it. If it's raised at all, replace it because it's damaged inside.

[Guest guest]

ErnieHorning wrote:

It's probably in the power supply. I've seen capacitors work equally well backward. In backwards, it has some resistance which will generate heat. Over time, and this will be variable, pressure will build up inside. The top has partial cuts in the aluminium cover which will initially bulge and split releasing the pressure. If it's not bulging at all, I wouldn't have a problem reusing it. If it's raised at all, replace it because it's damaged inside.

Yea, I remember that bulge well on a supply I built a long time ago, not paying attention to the voltage rating for the cap. I saw the rubber come out the bottom, the top bulge, and then, well, never did recover the can itself...Not a polarity issue, more a first time design not paying attention to details issue..:?

Thinking about it, yea, assuming it is just filters for the feed to the two regulators.

[jjd35]

thanks for the input. I was afraid of that not sure why I caught it now everything seemed to work all the channels tested and worked. Better to fix now then in the middle of december. Thanks again everyone

[gizmomkr]

I have had them bulge and leak over time (with correct polarity) but when installed with reverse polarity, I never had one make it longer than a second before it smoked and poped.

For a really great show, take a DC cap and feed it 120v AC. The tiny ones just go "pop" but the big ones spray out smoke for several seconds- that would be the electrolyte cooking, and Im sure its some level of toxic.

[ErnieHorning]

Typically I've just seen capacitors bulge. Many years ago I over voltaged a small capacitor just to see what would happen. I'd heard that they could explode and wanted to see just how much it was. I think it was a 10µF cap around 10 volts. I believe I applied 20 volts DC to it and stood back and watched. It took about 30 seconds and snapped like a small firecracker and sent out a circular streamer about 3 feet long. Pretty cool I thought but I've haven't see it since.

I've seen it blow gas out the top a few times but it's no more excitement then the hiss of opening a soda can.

The electrolyte inside is a mild acid so the gas that's expelled probably shouldn't be breathed though it may not be that big of a deal either. I don't see any warnings about it. Years ago, we used to play with the mercury from a broken thermometer and now they evacuate the whole building when someone drops one. As far as I know, no one had any problems because of it. OK I guess I like flashy lights more now so maybe that's it.