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Picture of Repair your electronics by replacing blown capacitors
Checking for blown capacitors in your malfunctioning electronics is fast and easy if know what you're looking for.  Replacing one part at a couple dollars a piece is much cheaper than replacing an entire monitor for hundreds of dollars!  Monitors, digital converters, and other video- related electronics commonly have power issues that are caused by faulty (read: low quality production) capacitors.  Common symptoms include:

- Unit won't turn on
- Unit won't return from standby
- Unit turns on and off intermittently
- Screen flickering or distorted
- Lines across the screen

If you're experiencing any of these, it's worth taking several minutes to check your circuit board capacitors. 

Step 1: Tools needed

Picture of Tools needed
Checking the capacitor just requires your eyeballs but replacing them requires a few tools:

- Screwdriver, hex wrench, or whatever's needed to open the case
- Soldering iron
- Replacement capacitors (you will find the values for this in the following steps)

Also optional but helpful is soldering wick, which is available for fairly cheap at Radio Shack.

In this example I'm repairing a digital TV converter box that will power on, but does not activate from standby.
 
milkywayman1 month ago

Sometimes a bad capacitor has no external signs, this actually happens when they dry up. I had a failed PSU once, and I measured the caps using a cheap ESR meter (check on ebay). The failing cap had still the nominal capacitance but the series resistance was off - instead of being below 1 ohm it was a couple of hundreds! And the rest were also in bad shape, if they weren't failing yet, they would have soon.So if you're in the process of replacing one bad cap, do yourself a favour and simply replace them all :)

BainM3 months ago

also the capacitors i pulled off. i tested them with a 9 volt and my multimeter... is that not a good enough test because they seemed to work or do bad caps still hold a charge? lol. thank you and anyone feel free to jump in on this if you know

BainM3 months ago

thank you you for all this great info... I have a JL Audio 500/1 car subwoofer amp. it powers on and has no sound i looked everywhere and tested everything and it all checks out. i see the tops of the capacitors are bulging and they are 1200uf 100WV and i Replaced them with 2200uf 80V would this not be a good idea? i have not powered it on yet. i dont have any matching but these are the same type of caps with plastic tops instead of aluminum i pulled them from a hifonics 1200 watt amp. i just dont want to damage the board by powering it up and it not be a match.

iolamis7 months ago

I am trying to repair an Arri 1.2KW HMI magnetic ballast from 1995 which flickers irregularly. I found this capacitor which looks blown in that the top is convex, but I measured it with my fluke 179 meter and it came up 230uF. It doesn't seem shorted as I get very high resistance measurements (settling around 11KOhms after starting much higher as I assume the meter battery charges it slightly confounding the resistance measurement). Since this has a black plastic top without any grooves, unlike the metal tops with grooves that I typically see, I'm unclear about whether this means it is blown.

arri_cap.JPG
ooofest11 months ago

This was successfully applied in fixing a subwoofer for an Advent AV190 computer speaker system - even down to the "blown" capacitor picture resembling my issue. Very helpful, thanks

jmichaels41 year ago

Is it possible to have a blown capacitor WITHOUT any visible change in it? That is, no distortion of the top, etc.?

Yes! Use an ESR meter and/or capacitance tester to check (they are not the same as a multimiter though some of the very expensive ones will come with the functionality) the capacitors. They run about $80 for a decent ESR meter. If your electronics aren't worth that much I would simply replace them, though.

iq2011 year ago
Discharge all capacitors in the vicinity. It's best not to assume they're all discharged.
jgeidl1 year ago
Nice job. I love hints.
raptor4022 years ago
Hello, sir/ma'am

Your instructable is wonderful. I have a question: I have an XBox 360 slim with a 100-127v input power supply. In my country, the wall outlets are all 220v, so I was using a step-down transformer with the console. Unfortunately, I tried out a smaller converter without reading that it was not transformer based. To sum it up, there was a bang and some smoke.
I opened up the adapter and found that one big capacitor had burst open (that was my first guess as I had seen a capacitor burst with my own eyes, and that was my own doing) and the electrolyte was spread around. I cleaned up the electrolyte and tried the adapter. The console would work for a minute and then shut down, implying that the rest of the adapter is function.
My question is: will replacing the capacitor fix the adapter and make it usable again?
rbennett83 years ago
i can vouch for this i had o recently recap my 26" lcd tv due to it turning on and off intermittently

i recommended this site they will help you out a lot with the process

http://www.badcaps.net/

http://www.badcaps.net/forum/

also the desoldering wick from radio shack from my experience is junk

this one is good i have not had a problem with it yet
http://www.drillspot.com/products/1429031/Tech_Spray_1811-5F_Desoldering_Wick?s=1

crowman733 years ago
I'll definitely use this tip in future, thanks.
thank you sir, very helpful.

i had a DVD player stop working, turns out it blew the switching power supply IC, and a fuse as well. I replaced them and the unit still didnt power on.

i had overlooked a couple of blown caps, so thanks for reminding me to take a second look! all is functioning well
Dr.Bill3 years ago
I always suspected the tops of the caps were scored for a reason.
Horsehockey3 years ago
You say to note the polarity of the capicator. Trying to determine the polarity of capicators, especially on well pump motors or other outside erquipment, has always baffled me. Maybe the little blue capicators have the polarity on them.
I have asked many highly intelligent electronics technitians how to determine if a capacitor was bad. Their reply was that if they thought it could be bad they replaced it. You are the first person I have seen that has come up with a simple way to dewtermine a bad capicator. Thanks for sharing.
fhidiort (author)  Horsehockey3 years ago
Usually electrolytic capacitors have a stripe with minus signs down the side that indicate the negative lead. You can see in the Step 5 picture the blue capacitor has a black stripe with blue minus signs- that's the negative end. Also on some circuit boards (including the one used in this example) the polarity is marked on the board itself with a little plus and minus sign.
dimmaz883 years ago
Awesome instructable. The trick for identifying the broken capacitors is great, I've always wondered how to do so.

Thanks for sharing.
coming from non electronics i was really glad you explained the thing with simplicity. Loved it !
fhidiort (author)  dimmaz883 years ago
Glad it helped!