Tag: capacitor

The Ubiquitous Wall Wart

For those of you who are unfamiliar with the term “wall wart” it is simply a slang term for external power supply’s that hang out of the outlet. The power supply has evolved over the years from being something external to the apparatus to be powered, cabled to same with large cables.

As technology “evolved” the power supply was integrated into the apparatus and a simple cord connecting it to the AC line was all that was needed.

After even more “evolution” the power supply went external again on some apparatus’s in the form of a wall wart.

It was during this time the wall wart was blamed for starting fires. Many firefighters attributed the source of combustion to the wall wart.

Early wall warts were not fused or if they were the fuses were defective. I still vividly remember smelling something “like hot plastic,” finding a wall wart going to a radio was melted, very hot and still pumping out energy into a short length of cable that the cat had chewed on causing a short.

These power supplies still use energy even if the apparatus is powered off. Those “green” people will tell you to unplug them when not in use as they waste energy. I would tell you to unplug them simply because “in my opinion” they are still a fire hazard.

Unplugging them can be a pain in the rear as often times they are buried behind something etc. To this I would encourage you to get a power strip that you could turn off the whole thing when not in use rather than trying to plug and unplug every time you wanted to use the device.

Case in point. My phone stopped working. When I did my “electronic technician thing” I discovered that the wall wart was dead.

Finding a similar wall wart today has not been successful. It is a 7.5 volt with a current rating of a 1000ma. The real trick is finding one with a 90 degree bend in the plug as to fit into the bottom of the base.

Looking at the wall wart “I dissected it,” the failure was a capacitor that failed. This should not be any surprise to those of us who work with electronics as there is a raft of faulty capacitors in the marketplace which are responsible for the early demise of many many things! From computer power supplies to flat screen TV’s to just about any electrical device made in China. Read all about that subject here. http://www.badcaps.net/

This too made a smell which alerted me to the fact that something was awry. The interesting part of this is the internal fuse did not blow. Had I not been home and smelled the “hot smell,” would my house still be here?

Because it is in an airtight container one has to think that any flame would have not had the oxygen to burn and eventually the fuse might have blown or the circuit breaker to the receptacle might have tripped. The short answer is “we just don’t know.”

Looking at the device you can see that they have dropped the 120V to 12V with a large 10ohm resistor. From there they have rectified it, regulated it and I would guess cleaned up the dc and even the AC with a few small components. You will note the top of the capacitor is puffed up which is a clear sign that it is defective. You will also note that the board is discolored where the devices got hot when the capacitor failed.

All Wall Warts are not the same!

I frequently am asked by different people to repair some small appliance. I enjoy doing it so it is not much of a burden. More often than not I am brought the device that no longer works with a wall wart that is not the correct wall wart for the device!

Looking at the back of the apparatus you will notice that there is just about always a picture or depiction of the place that the wall wart plugs into the unit. That depiction will usually have the voltage and current required as well as the polarity of the plug.

Back not too long ago it was anyone’s guess if the center was positive or negative and, the information about the voltage, current or even if it were AC or DC was just not there.

Looking at this early wall wart “from the 70’s” you will note that it is small in size and has a plug on it that when inserted into the radio momentarily is greeted with a short. This type of plug should not be used for power. This charger is rated at 9volts dc with just a few mils of current. The reason for this is it was designed not to run the radio but to charge the batteries inside it. While the radio that this goes to is otherwise a good radio this is a poor design. Admiral would have been far better off to include the power supply inside the radio capable of running the radio as well as charging the batteries instead of using this, (which was a cheap alternative.) Also note that the plug is broken and should be repaired before use. Interesting to note: this supply is not regulated and in fact cranks out 21volts DC with no load.

With older devices I have to check before simply plugging in some sort of power source as some of the older radios that I mess with were made before any standards were envisioned.

Some manufactures made positive the ground, which makes an interesting troubleshooting exercise for those of us who are used to negative as the ground.

We all end up with a box of these wall warts before too long and often times they are not labeled as to what they went with. My guess would be that the manufacturer of the device purchased power supplies from some vendor that would work with their device and a host of others.

It is a good idea to label what device that wall wart came with if it is not so labeled on the power supply itself. I have seen some use a silver Sharpe to label them which is a great idea!

Things to note when looking at your apparatus and trying to match up the wall wart. Voltage required, Current required, size and type of connector, polarity if DC, or is it AC?

If you have cats you might want to examine the wires from time to time as some cats or other critters like chewing on cords. For people in this predicament wrap your wires in “spaghetti.” No not pasta but something called spaghetti which is a tough plastic coiled covering designed to keep all the wires together and neat. It also deters small critters from chewing on them. Larger critters may need better solutions like Panduit. I have found some of these things at IKEA. Electrical Supply houses are another good bet and of course there is always eBay.

I would be remiss not to mention your smoke alarm at this point as many of us loose some ability to smell as we age, or have a cold, or what have you.

Feel of your wall warts from time to time, warm is normal, hot is not! Some power supplies for laptops get too warm for my taste, but I think they would tell you it is normal. If in doubt, have it checked out. Safe rather than sorry is not a shabby way to live your life.

Look under the desk from time to time and examine your wires and cords to make sure that they have not been cut by the chair rolling over them or some other heavy object sitting on them. This is especially true of your children’s room. I was in a house doing some computer work when I noticed that there was probably 30 plus amps of current being taken out of one wall receptacle. The wires under the desk looked like a bowl of spaghetti “the eating kind” and there were heavy objects sitting on the wires along with them being under the rollers of the chair.

Wall receptacles in most houses are not made for this type of use. The bedroom may be on one 15 amp breaker and the outlets wired with number 14 wire; which is basically made for lighting. These are all things to look at when putting computers in bedrooms. The good news is that again technology is becoming more efficient and less current is used with newer devices than older. It is still something to talk with an electrician about if you have the slightest cause for concern. The simple fact that this kids breaker did not blow for his room really bothered me in that he had a gaming machine, three monitors and a plasma TV… Add to this the stereo, lights,fans, guitar amp and other electrical things other than this being one spoiled child there was simply too much in that room for what the circuit should have been able to provide.

Feel the outlet covers, are they warm? They should not be….

-Best to you and those that you care about!

Electronic News

Many of you will not really have much knowledge of what I am going to talk about here as it relates to the electronic industry and your pocket book. By the time your done reading this, you will be enlightened somewhat.

Not too long ago some Chinese company produced something known to me and anyone who knows technology as a capacitor. These live in just about any electronic device that you might have.

The problem is that the formula for these was invented in Japan and it was liberated “Stolen” from the Japanese plant and sold to someone in China. Industrial espionage happens all of the time and there are many famous cases that I could site; The TV and Radio are two off the top of my head.

The problem with this formula is that they did not get all of it. They got the part for the dielectric, (the part that separates the internal plates from shorting) but they did not obtain the stabilizer for the dielectric; so after a few months to a few years the dielectric breaks down and fails. These capacitors were sold to many different manufacturers including Dell and LG to name two.

Other computer board manufacturers are also loaded with these defective capacitors. One of my LG monitors stopped working and for about $6 and change and about one hour worth of work, I replaced all of the capacitors on the power supply/ inverter board and, Viola; the monitor is as good as new. The most difficult part of the procedure was taking the monitor apart without damaging it.

Last night one of my desktop crapped out. The power supply went south. I happen to keep new power supplies on hand so I simply upgraded the power supply from 300 watts to 600 watts which also sports a larger cooling fan. It was a win win!

As the power supply houses some pretty cool parts for those of us who still build things, I took it apart and there it was, a capacitor that was bloated, standing out like a sore thumb. The fix probably would have cost me $.50 but as it was a 300 watt power supply I elected to scrap it. 300 watts is really too small, and of course much cheaper than a 600watt.

A few weeks ago I was working on a dell for a gentleman and the onboard video card was working terribly. There were lines in the picture and it was not syncing correctly. Examining the board around the GPU I noticed, you got it, puffy capacitors. I installed an inexpensive video card and turned off the internal one. Problem solved until some of the other capacitors in the box fail.

A friend of mine works for a City here in Texas and part of his job has him traveling to the Dump of all places. There in some building at the dump are flat screen TV’s microwaves and so forth that have been discarded. He picked up several flat screen TV’s that were discarded and for a few dollars repaired them. While he is the ultimate recycler, it is a shame that we do not repair things any more. One has to wonder if we are spending too much time with video games instead of tinkering. One night at dinner with some friends I was gob smacked to learn that one of the guys at the table had no idea how to change spark plugs. These are the type of people who call on people to do things for them. While it may make financial sense to do this I simply cannot pay someone to do something that I am perfectly capable of doing with a few exceptions.

This week being “earth week” I would encourage you to think about getting things repaired instead of trashing them when they break. Electronics are known in the industry as Ejunk. There are companies that specialize in recycling this type of thing but, they are becoming harder to come by. I suspect that the EPA makes this type of business a tough one to run, and not be out of compliance in some small way.

Most of us have no reason to know this but, the dumps all over the country are filling up. There is a dump not too far from me here in north Texas that at one time was low land covered in water; and is now reminding me of the foothills in NorthernCA.

A lot of this e-junk is shipped to third world countries where families hover over open fires, melting the solder with the fire, removing the parts off the circuit boards for the metals that they contain. Since it is an open fire, the board is blackened and the people doing this breath in those toxins along with their children who are helping. It does not even stop there as this residue litters the grounds, the water supply, the air, and what have you. We here in this country do not have a clue; we simply think that we do our part by most of the time, throwing that soda can in the blue bin. Once we toss stuff into the bin do we ever think about it?

I come from a time when there was not so much stuff trashed. I bought a broken TV at a garage sale for $5 as a kid; and learned how TV’s worked and for about $3.50 for a new high voltage rectifier tube, I had a nice looking portable TV at the age of 10. At 13 I wanted money to buy a new CB and antenna. Mowing lawns seemed like a good job. One could make $4 a yard…. Currently I pay $25 a week, and this is one thing that I will not give up. As I put my plan in the early 70’s together, I would first need a lawnmower as my dad was dead set about me not using the family lawn mower on others peoples yards. He was right to be concerned as I killed 3 lawnmowers on one person’s yard for $2. That is another story..

Again I went to garage sales and found a lawn mower that did not work. I pulled it through to make sure that there was compression and nothing bent, and bought it for $15. After a trip to the library checking out a book on small engines, I digested the book. Lawn mowers have points and a condenser under the flywheel and those are known to be problematic. I checked for spark and there was none. The local grocery store sold parts such as these and for a few $$ back in the day, so I now had my own lawn mower.

I purchased three lawnmowers all together in similar fashion along with an edger. Gas cost about a quarter to fill up my can and that would last me about a week. I created my fist direct marketing campaign at the age of 13 with three sheets of paper, two pieces of carbon paper and my best penmanship that I could muster.

I mow yards

Please call 242-XXXX

For an estimate, ask for Scott.

I wrote this until I filled up a sheet of paper and then cut them out much like Avery labels would look today. Armed with a shirt pocket full of “flyers” and some scotch tape I went door to door canvassing my entire neighborhood.

The interesting thing about all of this is that those types of campaigns have about a 2% return or hit rate. That was the figure 42 years ago and oddly enough, that is still the figure today! I still do direct marketing campaigns; just not to do yard work. J

I did this for several summers; it paid for my first car, and lots of photographic equipment, and oh yes a CB that quickly turned into Ham Radio equipment.

Where are those entrepreneurs today?

As you can tell, I still do this today. Not that I go buy things at garage sales to repair but, I do restore antique radios that I have purchased either online or from individuals. Some just make their way too me as friends know that I do it, and they are tired of storing it.

So when your flat screen TV dies if you know anyone with any technical prowess, have them search the web to see if someone has posted a fix. It may very have been me. Have them try it. The parts are available in the form of a kit from some people online for as little as $12.

There is a good feeling that comes from repairing something that otherwise would have been put into that growing mountain of pampers, kitchen waste, and of course defective electronic devices that needed about $6 to $10 in parts.

As a side note I did this with cars as well. At one time I had 13 cars which I bought for next to nothing as they were broken. I picked up parts from a junk yard that the owner had an old TV, which always needed fixing. I would fix them and sell them and I enjoyed the process. That was back before the computer was installed into the car which controls everything relying on sensors for information.

Like the lawnmower, back then you needed spark, gas, air and compression. Today you need an analyzer of some sort that can interrogate the onboard computer and find out what the failure is. Usually some sort of sensor that you did not know that you had.

-Best to you and those that you care about!