Training session 13: Fixing Hardware
Learn how to fix 'broken' Hardware
However rich you are, there is still a point to being able to fix your own hardware. For the less rich, you can save yourself money from having to buy new parts, and even make money from selling parts you have found and fixed. For the rich and usually stubborn, it gives you the skill's you require to 'tweak' or 'mod' your hardware, would you fancy a blue light on your monitor rather than that boring old green one? or would you prefer an LCD panel on the front of your box that tells you the temperature? Well then you could still gain from learning a little about fixing computers.
I cant keep count of how many times ive been going down the road, seen a monitor sitting there because the owner thinks it is beyond repair, or the times when i have found a mate with twenty 'broken' monitors in his back shed, and offered them all for a carton of beer, or even when i have walked into a second hand shop, seen a monitor sitting there for the cost of two cans of coke, with a sticker on it saying it is blurred and therefore worth hardly anything. How stupid are these people...
First thing to do is take the monitor and plug it in, if it starts great, if nothing happens dont start abusing it. Turn the monitor on and take the cover off, dont worry about the power, just dont touch the big red wire above the tube, and try not to touch anything metallic, normally the cover is only held on by four screws and maybe a clip if the monitor is a crappy custom brand like acer. First thing is to look for the fuse, 50% of monitors that are chucked out merely have a blown fuse. Replace it with another one and try again, if it turns on laugh at the person who ditched it. If it doesnt pull out the trusdt multimeter and do a check on the switch, quite often a wire on it has just worn out, or the switch itself has worn out. If you dont have a multimeter just short the two wires, if it still doesnt work the monitor is pretty much dead, i dont recommend fixing the circuit board, but it can be done, but is normally not worth it unless it is a nice 21 inch FD Trinitron, but people who pay that much for a monitor normally wont chuck it out. If you wish to try to fix the circuit board, read ahead and continue as if it was a power supply, as monitors obviously have them, they normally can be fixed. The following bit only applies if the monitor turns on, but is either got stuffed up colours, is missing a colour, or is blurry. If you look around the inside of the monitor you will notice atleast three screws that dont hold anything in place, if you are lucky they will be labelled, but quite often arent. If the monitor is missing colour, or has too much of one colour, slowly turn these screws. Labelled screws will normally read, red, green and blue. Turn them extremely slowly and you will notice colour is removed and added. With a little playing your monitor will look right. Now if one of the colours appears to be off centre, in other words you see one screen that appears to be red and green, and another copy of the exact same screen a few millimetres away that is only blue, you can also fix this. There are normally three or so levers that rotate around the back of the tube. Turn these slowly until you find which one is the colour that if off centre and you should be able to fix your prob. Lastly if the monitor is blurry, look around the monitor for a screw name sharpness, it is normally grouped with contrast and a reasonable distance away from most other screws. Turn this extremely slowly and voila, no more blurry picture. How easy was that to fix.
CD Drives are normally rather reliable, but they are known to sometimes 'wear out'. Most people are surprised to find out they are rather easy to fix in most cases. Let me first explain basically how one works, a laser is fired into a mirror, which is reflected thru a lense, which hits the CD. If the laser is reflected the value of that part of the CD is a binary one, if it refracts and does not reflect properly, the value is a binary zero. Contrary to most peoples beliefs, the laser never actually moves, it is safely secured near the back of the drive, the lense and mirror move, which are both driven by a small survo motor. Take the drive apart and clean the lense, be careful not to apply much pressure on it. Turn the thing on, if you have the case off, make sure you dont look at the laser, even tho it is rather weak, it can still do damage. You may be lucky and it will work, if not, and the drive is detected by the computer, just no CD's can be read, open the thing up and check that the servo motor is actually working, going back and forth to read the CD, if it isnt, all you have to do it get another servo of the same voltage, a soldering iron, and solder the servo into place. If it still doesnt work, check to see if the laser is actually emitting something, hold it infront of a piece of paper, turn it on, and see if the laser can be seen on the paper. If the drive just wont open this can be easy to fix, check the switch on the drive, short it to see if it still works, check the servo that moves the tray to see if it still works. A nice place to get servo's from is old broken floppy drives, quite often they are just the right size. You can always try fixing the circuit board if you have no luck, but please refer to the power supply section as this is not an easy task.
Have you ever walked into a music CD shop and seen a CD cleaning kit on the counter and thought, "hmmm, that could come in handy..." Well if so you need a lesson in how CD's are made, and the budget way to clean them. Basically What a CD is, is a piece of plastic, with an aliminium coating on one side which is the side that is actually burnt onto, and a protective coating over this. The colourful picture side of the CD is really the side that holds the data, and is therefore more important than the plastic. You can pay larger ammounts of money and get the plasic side replaced, but why bother. When a CD is playing up, check the picture side, if it is scratched to hell and you can see the plastic, then even those expensive CD cleaning kits are a waste of time. But if that side is fine the following will work quite nicelly. The plastic often gets scratched alot, you lend a CD to a friend and when you get it back, his little brother decided that it works better on the floor than in the CD Drive. Go into the garage and find some Car Polish, check the label to see whether it contains abrasives, if it doesnt go look for another bottle, or look for some other cleaning agent you have lying around that contains abrasives. Put a little on the CD plastic side, and use a rag to rub it in, do it for a few minutes if the CD is in really bad condition, try not to get any one the other side. Use a clean cloth to wipe off the Car Polish, the scratches should have magically disapeared, if not do it again. Put the CD back in the drive and check to see if it reads properly now, if not clean it again. So howcome Car Polish is cleans more than cars, and actually cleans my CD's? Basically what those CD Cleaner kits do it cut away the top layer of the CD, making the laser bounce back properly instead of refracting, deaper scratches need more layers removed. What your Car Polish does to your car is exactly the same thing, it removes a layer of paint from the shell of your car. That is why you need to use Polish that contains abrasive or cutting agents, so it removes the top layer off the CD. Now dont you think a bottle of Car Polish is much cheaper than those piddly little bottles of CD Cleaner when they are nearly the exact same thing? If your CD has deep scratching, and after a few coats of Carl Polish, you still cant read anything here is a method that sometimes works. Take your CD and put it in the freazer, thats right, freaze it dont worry about damaging the CD, just make sure you freaze it nicely for five or ten minutes. Take it straight from the freazer, quickly wipe down the CD with a cloth and put it in the CD Drive and immediately make an image or copy it as soon as possible. The moisture from the fridge acts to fill the scratch's, since the moisture is frozen in place, it gives you enough time to quickly make a copy of the CD and retrieve your almost lost data.
Power supplies are a little bitch, they are always blowing up, normally that broken scanner in the corner of you room isnt actually broken, just the power supply it uses has stuffed itself. Too many people seem to believe that the tiny transformer inside it has blown, i would really like to know how a coil of wire blows up, or how a piece of ceramic formed into a resitor blows up, it does happen, but very rarely. A tranformer takes a high AC voltage, and step it down to around the 12 volt DC current. Power supplies for computers, scanners, monitors or basically anything with large ammounts of circuitry have to regulate the power supply. This means that the Power Supply with only allow a set ammount of current and voltage flow thru it. The basic cicuit for a power supply consists of four diodes, one filter cap capacitor, a 7805 IC and another standard capacitor, which would output +5v and have a ground lead. The 7805 IC is diferent depending on the desired Voltage, if a diferent voltage is required, the IC is either going to be a 78XX or 79XX, where XX stands for a number, and the circuit requires two resistors. To increase the current, the circuit requires a transistor, a resistor, and another capacitor to be added. So from this we can say that the circuit in the power suplly we are trying to fix will contain the following:
Filter Cap Capacitor
78XX or 78XX IC
You will probably fins a variance in IC's but the rest of the components should be on the board somewhere. Quite often a Zener Diode or Signal Diode is also used, and a fuse. First thing to do is obviously check the fuse and the switch. Every Power supply that is gives a Variable Regulated Voltage output requires as voltage regulator, this is the component that creates the most heat on the board, and therefore is the most likely to break. If the fuse isnt blown i recommend checking this next. It looks similar to a transistor, but it has a hole in the top which is normally screwed into a small heatsink. Use the trusty multimeter to check any transistors, as they are often at fault, also check the standard diodes. The signal or zener diode are also quite often at fault. The zener diode acts as a secondary fuse on the ciruit to protect the IC's in most cases. To check a transistor you have to apply the correct ammount of volts down the correct two wires, and the third should emit power. If you have little electronic knowledge you should know a transistor acts as a switch. Check the capacitors by applying the correct voltage down the wires. If there is a rather large transitors on the circuit, that often has a piece of metal behind it acting as a heat sink, this is what is called a voltage regulator. It is used in voltage regulated Power Supplies. Basically any power supply that outputs more than one diferent voltage. Check all the componets that are either capacitors, transistors, or diodes before checking any of the resistors as they have little chance of blowing up. Hopefull with a bit of soldering and tinkering you should have a working Power Supply. This knowledge can also be applied to fixing other circuits, chips can sometimes be replaced, but are tricky to solder in. I do not recommend soldering motherboards, or PCI cards. This is because most of the time it uses two or more layer curcuits, this means it has one circuit, and then another directly under it. So if you solder and fix the top circuit, you could easily damage the bottom circuit. But if the device is totally stuffed, and you feel lucky, have a go, you might be lucky, just some advice, the circuits on these two or more layer boards are quire often very receptive to heat and can easily be munted even more.
Hopefully now you should have a simple grasp of how to fix electonic devices, all of this applies to nearly everything, TV's, VCR's, Stereos and basically anything electronic. Rubbish chuckout days are often a good place to find things that can be easily fixed. Look around for things that are supposedly broken in the local second hand shop. Maybe even go thru a few dumpsters of computer repair places, they normally dont even try to fix stuff, just chuck it out and get new stuff. Every once and i while i go round to places finding blown and 'blurry' monitors, take them home, fix them, take them to a second hand shop or sell them in the paper and make more money in one day doing stuff that is half interesting than if i go to work for two days doing something i hate. Have fun and make yourself some cash on other people stupidity and slackness to get something fixed or do it themselves.