Home electronics repair: Capacitor replacement for dummies

I've had a few household electronics failures caused by failed capacitors.


My Refrigerator uses a control board to run everything and I started having problems with the ice dispenser and light not working reliably, before eventually failing to work all together.

I noticed that the two above capacitors were starting to bulge out the top, the easiest indication of a failure. 

The tops of these should be completely flat. These had bowed out visibly and started to open up slightly in the center.  Replacing these fixed all of my issues.  

This summer my central AC stopped working.  The fans would run but the compressor wouldn't turn on.  When I opened up the service panel on the outdoor unit, I found that the run capacitor was failing.  The end cap was rusted over completely and some of the waxy electrolyte inside had leaked out.  These sometimes explode when failing too, making it very obvious when one has failed.  If your AC unit is more than a few years old, theres a good chance you can replace the run capacitor and fix the issue.  A typical compressor should last through several capacitors.

This is usually a sign that the capacitor should be replaced.  

The new capacitor in place, note the shiny end cap. 

Theres a few reasons that capacitors tend to be the failure point.  They're an expensive, bulky, yet vital component in modern electronics so often tradeoffs need to be made.  A smaller capacitor can fit in a more cramped housing, but won't last as long, larger capacitors tend to be more expensive, and a device may be simply be poorly designed for its operating environment.  Overheating is what typically causes capacitors to fail, but usually this is due to one of the previous reasons  letting it overheat in the first place.  There have also been incidents when cheap manufacturers have used stolen copies of stolen copies of electrolyte recipes resulting in capacitors that did not meet the proper spec.  A batch of these bad capacitors made in the early 2000's found their way into all sorts of electronics, and Dell had an issue with a nearly 100% failure rate with one of their lines of desktop computer within one year, all due to using cheap capacitors.

Diagnostics

Typically if an electronic device stops working suddenly, the issue can be traced to a bad capacitor.  You can see the brown one on the left is bowed out on the top a little, and is smaller than the same spec cap from a known quality electronics manufacturer.  Other symptoms include powering on for short periods of time, random device resets, squealing sounds coming from the device, etc.

Sometimes a capacitor will start to leak, and the electrolyte will corrode nearby components

Repair

Once you've identified that a capacitor is bad (or if you want to try replacing the caps before tossing the device in the junk heap, you need to get replacement capacitors.  Radio Shack still sells a few sizes but for the most part you'll need to order online from a catalog like Mouser (no minimum order, just shipping costs) or Digikey (minimum order size of around $20, plus shipping) The 2 numbers you need to match are the voltage and the capacitance (in this example, I'm replacing some 16V, 2200uf and 200V, 47uf.  These are usually marked on the side of the capacitor.  If you can't find an exact match, you can safely use a larger size for both values, but keep in mind that this usually makes for a physically larger capacitor as well, so the closer the match, the easier the replacement will be.  For a large run capacitor like on an AC unit, make sure to use a compatible part as these are often multiple capacitors in one can.  I looked up the model number for my AC unit and searched on Amazon for a compatible part number.

Tools and Skills

You should have some experience with soldering to continue.  I use a 30w soldering iron, this job is much easier if you use a good iron or soldering station.

The other tools you will need are:

Soldering Iron
Solder extractor or desoldering braid
Solder
Offset/Diagonal cutters

If the board is not clearly marked, note which side the negative (-) side of the capacitor is facing. The lighter stripe and - sign indicate the negative side.  This board is also clearly marked for each component.  

I remove the old capacitor from the board by heating the solder around its terminals and using the solder extractor to suck the melted metal from around the contact.  The extractor has a spring loaded piston which is released by pressing a button, creating a strong suction.  

The old capacitor can now be pulled free, note the clearly marked + side of the board.  The longer lead on the new capacitor is the positive (+) and the shorter the negative.  This is also marked on the side of the capacitor as noted previously.  

I bend the leads outwards to hold the capacitor in place while I flip the board upside down to solder. 

The solder should flow cleanly around the lead and board

And the excess leads are cut away.  

Better than new.  By using higher quality capacitors than the originals, I shouldn't need to replace these again for awhile.

Piezo buzzers in the home are sometimes too loud

I have a few UPS units and a power inverter around my home that all use piezo buzzers as alarms.  These are designed to get your attention to let you know the UPS is running on backup power or that the battery driving an inverter is low.  Often these are used in office or noisy server environments so the buzzer needs to be loud enough to cut through the noise to let you know this is a problem.   

I've found this to be too loud, especially with some of these in my bedroom.  I can usually tell when the power is out so I don't need the UPS to tell me.  Some newer UPS units have a way to disable or change the volume on the alarm, however most cheaper units do not.  Many people fix this by cracking open their devices and either desoldering or cutting off the buzzer.  

A far easier fix is to put a small piece of packing or scotch tape over the buzzer.   This does not completely silence the alarm, but makes it significantly quieter, and can easily be reversed.  The tape minimizes how much air the buzzer can vibrate, dampening the sound.  

If you're not comfortable opening up your electronics, find a teacher to assist you.  "No user serviceable parts inside" is manufacturer speak for "be careful when doing something stupid"  

Capturing wild food

Occasionally throughout the year I have opportunities to get great locally grown or wild grown food.  My parents keep a sizable garden most years, and I frequently get strawberries, tomatoes, butternut squash, etc depending on how the season happens to be.  There's also a few large patches of wild blueberries that grow near where I grew up.  It's currently scallop season out on Nantucket Island and I'm fortunate enough to bring some home when there's a good season.

It's a good season. 

Scallops have blue eyes, one along each of the ridges at the edge of the shell.  They have one large muscle that they use to open and close the shell rapidly, creating a jet of water out the back and allowing them to move along the sea floor.  This muscle is what we eat, and on the Nantucket bay scallop, this muscle is small, sweet and extremely rich.

We go out at low tide, when its shallow enough to wade out into the bay, and a rake/net like the one above is pushed along the bottom, stirring up scallops, weeds and other shellfish from the bottom.  My dad has become quite an expert at finding them, some of the better pushes can find 20 or 30 at a time.

These are then sorted, discarding any junk, empty shells, and scallops that are too small or do not show a growth ridge, indicating that they've had one breeding season and are legal to harvest.  The sorting table shown is my dad's design.  

A couple hours work with my dad pushing and Matt and my brother sorting, and we have our bushel quota for the license.  A bushel yields about 6 pounds of cleaned scallops.  

My dad openen the scallops, using a shellfish knife to pry the shell open and leaving the uncleaned half shells for Matt, my brother and myself.

The guts are then pulled away from the muscle, leaving just the half shell with the muscle stuck to it.  The muscle is then cut away from the shell and saved.  

The discarded shells and other material is dumped at a public drop off dumpster closer to town. 

The odor is rather strong.  

We prepared some of them ceviche for today's lunch, soaked for about 24 hours in lime juice to cook the outer layer and give the scallop a nice citrus flavor.  The lower picture shows how deep the citrus cooking soaked into the meat.  We used a recipe my Mom found at Jan's Sushi Bar

http://www.janssushibar.com/avocado-scallop-ceviche/