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PC Repairs

Please note I take no responsibility for any damages caused by people using the following advice.

Please note I take no responsibility for any damages caused by people using the following advice.


  1. Cleaning contacts. As a PC gets older you my find it develops the odd problem, sometimes it might not boot up, or it might even boot at all. Sometimes it can be down bad contacts, or peripherals working themselves lose. While you can try re-seating some of the components, sometimes it might be necessary to clean the edge contacts with a pencil rubber.

  2. Dusting PC – Dust can be a bit of a problem when it gets into contacts and when it gets damp. Often you will find it tends to collect around were the cooling fans are. You will sometimes see dust building up around and outside the CPU fan, if the RAM is nearby

  3. Re-seating RAM and CPUs – Warning – NEVER START UP YOUR PC WITHOUT THE CPU HAVING IT’S COOLING ASSEMBLY IN PLACE.

  4. Right and wrong way to put on a CPU heat sink assembly

  5. Connecting on-board USB – Most boards after Pentium 1 have USB interface that just needs to be enabled in the BIOS and then a connector needs to be fitted to the motherboard. You can normally pick these up from your local supplier for about the price of a five-litre box of wine. The problem is how to connected it, while most manufacturers have standardised their connections now, it does not help if you have a board that is older. Luckily there are only two sets of four wires that need to be connected. They are Ground, +5 Volts, -Data and +Data. So what you need to do first is to work out were the Ground and +5 Volts are. You will need a Volt meter for this, set the meter to a DC voltage higher than you need, in this case above 12V DC will be fine. With the PC switched off, take one of the DC connectors that are used to power a hard drive or CD ROM – you will notice it has two black wires in the middle and a Yellow and Red wire on either end. Put you Negative (black probe) into one of the black connectors, it should fit with a bit of play, do not force it in. Switch the PC on, you can now measure the Voltage of the Yellow and Red Wire on the connector using the Red probe on the meter. Then Red wire should read +5 Volts, and the Yellow wire +12 Volts. Now you are ready to try and read the pins on the USB connector. With a steady hand see if you get a reading on the last and first in line of the pins, you might want to make a note of your reading on a piece of paper, those that you get a reading from should be the +5 Volts. Now put the red probe into the red connector hole, and use the black probe to check the pins of the USB connector on the motherboard, again the ones that give you a reading should be the ground connectors. Now here’s a tip, I have yet to meet a connector that was not connected this way, the pin next to the ground is Data+ (White) and the pin next to the +5V is Data- (green) Sometimes the connections are the same both sides, sometimes they are in the opposite direction (but in the same order) Have a look at the pictures and diagrams to give you a better idea. One of the problems PCs suffered from was the lack of ports available for other devices to be connected to the PC. Generally you had two serial ports and one printer port. If you had a modem and a serial mouse connected there was not much else you could add on, also these connections were slow by today’s standards, also IRQs (Interrupt Requests) were limited. The USB (Universal Serial Bus) solved this problem, most motherboards these days have two or six USB ports which you can connect cameras, printers, scanners and so on. USB 1 has a speed of 14 Megs per second and USB 2 is about 480 Megs per second. (a note on USB 2 – While it runs on Windows 98 once it has a driver installed, it does not run at full potential, for this you need to use either Windows 2000, XP or Linux)

  6. Connecting PS2 mouse – This is much like connecting the USB connector, but you might find getting hold of the connector a bit harder. Again you only have four wires to connect, and you find the Ground and +5V the same way, however some boards have five pins, and there is no easy way of finding which wire is which, you can try and look it up in the manual of the motherboard, if you do not have it, try and get it off the Internet.

  7. Power connectors – On PC there are two main types, the Old AT power supply and on most new PCs it is the ATX power supply. The main difference is that the ATX power supply does not require a power switch, and can be switched on and off by the motherboard, it should be noted however that this type of power supply is never really off, you will notice on a lot of motherboards that there is a LED that is on even when the system is not powered up, this is to warn you that the power supply is not on, but there is still power in the system, you should not really remove devices when it is in this state.

  8. Feeling the bevel in the HD power cable

  9. Care with VGA cables and PS2 mouse / KB

  10. Caps on motherboards

  11. No oil on printer

  12. Hard Drive and floppy drive cable. If one looks at the Ribbon conector (Normally flat Grey data cable) unless it has a key which is like a raised square on the black plastic conector) there could be two ways that it could be fitted. Normally Pin one is marked with a red line or red dashes. On the Hard drive pin one is normally nearest the power connector, you will notice that the cable has a twist, the twist goes to the floppy. On the floppy (stiffy) drive it is on the same side as the eject button. If the connector is the wrong way around on the floppy drive you will find the drive light stays on all the time

  13. Different type of screws. For most systems there are two different types of screw, the metric screw which has a fine thread and the Imperial which has a course thread. The metric screw is used for mounting the floppy drive or CD ROM and the Imperial screws are normally used for the hard drives and outer casing, the casing screws are normally cross recess (+) with a nut head. You need to be careful sometimes with regards to the length of the screw used, too long a screw can see you damaging the workings inside.

  14. Anti Static

  15. Flat Battery. PC systems these days have a battery that keeps the NV RAM settings, the date and time, together with what hard drive and other peripherals are installed. Over time the battery will lose power (after two years or so)

  16. The 1.44 Disk drive is a Floppy drive, although a lot of people refer to it as a Stiffy drive (Mainly in SA) if you look in My Computer the Icon says 3 ½ Floppy.

  17. What tools you will need, two rubbers, two brushes, small Philips, large Philips, Small flat, large flat, nut drivers.

  18. How to Solder and what Irons to use

  19. Double up on things so it is easy when things go wrong, for example a full house of RAM eliminates the dust in the slot problem.

  20. Do not use rubber bands to tie up cables, they turn to jelly, I had one that fell apart and ended up in the AGP slot, when the user came to up-date the system with a AGP card it did not work, they then went on to up-date the BIOS and made a mess of it thus rendering the motherboard useless.

  21. Up-dating the BIOS. DO NOT DO THIS UNLESS YOU HAVE TO – If you mess it up you motherboard will be useless as the BIOS (Basic Instruction Operating System) is needed for the computer to start. Here are a few good tips to avoid disasters. Go to the manufacture’s website, this is normally listed in the book or manual that came with the board, however if you do not have these you might have to look on the motherboard for these details, you need the Make and Model. For example Make: Gigabyte Model: GA-7VKML To fine the home page I normally do a Yahoo or Google search and type in the name of the manufacturer and then the words Home Page. Once you are there you can look for the downloads of the BIOS up-dates. Print out the Instructions for up-dating the BIOS and make sure you know exactly what to do. Most BIOS up-dates are done in DOS Mode and require you to boot up with a 1.44 Disk. Use a new, good name brand, DO NOT use a old disk. If you need to make a bootable disk this can be done in Windows by right clicking on the 3.5 Inch floppy and choosing the Format option, tick the Copy System files only box and click on Start. If you are doing it in DOS mode it will be Format A:/s - Once you have done that you normally have to copy onto this disk the BIOS up-dates and maybe the manufacture flash program, again follow the Instructions you have been given. Once you have your disk ready, run scandisk on it (Start / Programs / System Tools / Scandisk) Do a thorough scan on the disk and make sure it has not errors. If you are going to be running this disk on another PC, make sure that the drive is working properly and run scandisk (Thorough) on that PC in Windows before attempting the up-date. Remember that you have to boot from the disk that you have made, this means having the disk inserted in the drive and switching on, if the system does not boot of the disk check that the CMOS is set to pick it up as the first boot device, press Del(ete) or F2 when the system is starting up to get into the CMOS set-up. You will find the Boot order in either the Advanced set-up or in Boot up. You should be able to do the Up-dates using CD ROMS, for example you could boot with a Windows 98 Set-up Disk, remember it has to be done in DOS mode so you would have to select the Start from CD ROM and then Start with CD ROM Support. Just like the floppy drive the CD ROM needs to be set in the CMOS as the first boot Drive. Also note that some system have special boot disks that are needed to get into your CMOS set-up again check with the manufactures website. If things do go wrong there are a few ways you can get your motherboard running again. If you have a dual BIOS you can switch to the second BIOS. If the BIOS is removable, you can try and get another one from your PC supplier. If it a fixed BIOS – that is it is soldered onto the motherboard, you will have a problem, you would need to take this to a hardware repair centre were they can remove the chip and fit a holder, then the BIOS could be reprogrammed and fitted back. A very risky fix and one that I do not recommend that you try is to hot swoop the BIOS this requires a working board. Be warned that there are Viruses that can flash (Blank) your BIOS

  22. Putting a PC together or up-grading: The cardboard box test. LED the reset, Earth or short problem when mounting the motherboard in the case. Un-seating the RAM when putting in the power connector.

  23. Re-filling Ink cartridges. HP

  24. Bent pins on VGA cable, and PS2 connectors.

  25. Caps blowing their heads

  26. Don’t mix Windows 98 (First Edition) and Windows 98 SE (Second Edition) disks

  27. Disk Cleaning kits. Make sure your drives are cleaned and working, floppy drives should be cleaned with a disk cleaning kit, there is also a cleaning kit available for CD ROMs – When copying Data it is always a good idea to use the verify option, this checks that the data written is actually there. Floppy disk these days are not considered a good method of backing up data.

  28. Use a CDRW to test that a disk copies properly

  29. Dust in the heat sinks

  30. Check the fans are turning, oil noisy fans but better to replace

  31. AMD vs Intel CPUs – VIA 686 problem.

  32. Cleaning the optics of a Scanner

  33. Try looking on the Internet to see if anyone else has the same problem

  34. How Electronics work. To best to understand computers, it is an idea to understand a bit about electronics. This is a very simple overview of how things work to give you an idea of what is going on. Your main working element in electronics is the transistor. In PCs it is mostly used as a switch

  35. DVDs and CDs – Two problems I have noticed are that the Drive does not open.


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