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Critical Problems

(common problems which stop a PC operating or operating correctly)

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PC Start-Up

Windows Start-up/Re-install

Hardware Tips

No Power Up

Invalid CDRom Drive

 Hardware Tips

Hard Drives

Startup Disk

POWER SUPPLY SETTINGS

Hang up Before Starting Windows

Setting up Windows on a new Hard Drive

Illegal Operation Errors

Lost Setup Password

Windows has no device conflicts but won't start up

Beep Signals - Meanings

Device Conflicts

 Power Cables

Keeping a Hard Drive healthy

 

 

Errors & Hangups due to Bad Memory, Bad CPU Fan, Corrupted Files

 

 

 

Start-Up

Password on Setup not known/lost

Several times every year I am approached by people who want to get into the computer's Setup (386 PCs and above), but who cannot do so because a password has been set which they have forgotten or never known, here are some resolutions:

  1. Most modern motherboard have a CLEAR CMOS pins which when shorted with a jumper will clear old BIOS user settings. Enable this and then restart. In BIOS setup re-detect your hard drive(s) and save-restart.

In cases of old motherboards:

  1. If the setup uses American Megatrends BIOS, try AMI as the password.
  2. If the CMOS battery is removable, then remove it and leave the PC for 24hrs, reboot and you will be able to access Setup.
  3. If the battery is not removable:
    1. Check the motherboard manual for the clearing CMOS.
    2. If the motherboard is very old, it may have a dip-switch for this purpose.
    3. If neither 1 or 2 above applies:
      1. You can use Qbasic or Basic to POKE 0's (Zeros) into the area of memory holding SETUP data.
      2. Or... place a wire at the negative end of the battery and on the case and leave overnight. This should cause Setup info to be lost, including the password).
      3. Or...quite often if you take out a major component e.g. the Hard Drive and replace this with a totally different drive, the PC will automatically present or ask for Setup (irrespective of any previous password).
    4. On re-entering Setup, if all settings have been lost, you should re-detect the hard drive and ensure that the floppy is 3.5" 1.45MB, and reset the date and time.
      1. If you have no autodetect for the hard drive, then take the drive details (it's drive number and any other data specified on the drive), then use the Internet to contact the manufacturer (e.g: for a Seagate or Connor drive, use Seagate.com). Once at the site got to technical or drivers page and download the driver which has that drive number.

(whilst the methods above have proved successful on many occasions, PC Relief are not liable for any problems caused by the use of this information)

 

 

 

 

Windows95/98 won't load & can't re-install because system says 'Invalid Drive Specification' for CD Rom Drive (usually D Drive)

The problem here is not that your CD Rom driver has suddenly gone missing but that your Config.sys file is not calling for it.

When a CD Rom is first added to a system, a CD command is placed in the Config.sys file. However once Win95 has received this information and setup the CDRom, it then REM's the command out (puts 'rem by Windows95' in front of the Config.sys command - why - because it is not need for subsequent re-boots of Win95.).

Edit your Config.sys (in DOS, Edit Config.sys) and take out the remark in front of the command, (leaving the command to be used again), reboot and re-install Win95 using the CD Rom Drive.

 NOTE: Windows98 will boot from the CDRom and bring in an Oak Technology CDRom driver. To use this facility, set the boot up sequence in your BIOS Setup to 'CDRom' as the first device in the string. After Windows98 is installed fully don't forget to put the setting back to A,C,CDRom.

 

Drive Problems

Mixing old drives with new drives:

You can have real problems if you add a new drive as a slave to an old drive, if the old drive has a NON-DOS Partition. Compaq drives usually have one which is used as a dianostics partition. The Non-Dos partition can not only slow the whole PC system down but because it is not a DOS Fat 16 or Fat32 partition, it can seriously damage the new drive.

Resolution: Back up the old hard drive then use Fdisk to remove the Non-DOS partition. You will find Fdisk on any Win95/98 Startup disk (see below).

 

 

Making a Startup Disk

A Startup disk will typically contain the Win95/98 start programs (e.g: Command.com, Msdos.sys, Lo.sys) to re-start the PC in Windows 95/98 mode, to the DOS 7 level. It will then have all the programs necessary to carryout diagnostics / repairs so that the Win95 interface can be resumed (e.g: Edit.com - to edit autoexec.bat and config.sys, scandisk.exe - to fix hard drive/file problems) - and should everything need restoring - Fdisk and Format.

To make the CD Rom drive active in DOS:

Edit the diskette's copy of the config.sys and autoexec.bat's and take out the rem's for the CD Rom commands,

 

It would be a good idea to have a copy of any IDE CDRom Setup disk, so that it can be re-installed if necessary. You may also need to copy Mscdex.exe to the root of the diskette, and edit the CD Rom command in autoexec.bat to C:\mscdex.exe /D: <Name> e.g:MSCD000.

 

If you don't have a Windows95/98 Startup Disk then use Start, Settings, Control Panel, Add/Remove Programs, Create Startup Disk. Place a floppy disk in the drive and click the create button.

 

 

 

 

Windows has no device conflicts but won't start up

The PC may not start up Windows95 (or Windows98), so you try F5 on start up of Windows and find that in Safe Mode, there are NO devices conflicts (Start,Settings,Control Panel,Device Manager) - yet on restart Windows still will not start up ?????? - all you get is a blank black screen.

This problem is likely to be caused not by any devices not working properly BUT BECAUSE YOU ARE ASKING A DEVICE TO DO SOMETHING IT CANNOT DO. In most cases this is likely to be a screen setting that your graphics card cannot perform, such as a screen size of 1024 X 768. In Safe Mode, right click the Desktop, click Properties, Settings and adjust the screen size. Restart the PC and it will finally arrive at the Desktop without being in Safe Mode.

 

 

  

PC Starts but hangs up before starting Windows

If after starting the PC it hangs up without even counting the memory - this is likely to be a conflict between the BIOS on the Motherboard, and the BIOS of the graphics card (If not this, then you could have a fault processor).

Example: A Pentium 2 motherboard has a AGP graphics card slot but you can use a PCI graphics card in many cases. However a PCI S3 Virge card may have a BIOS which is not compatible with an Pentium 2 AGP motherboard.

Solution to this problem - Buy an AGP graphics card, take out the PCI graphics card, and place the AGP card into the AGP slot. On the next boot up, the memory should count up and the system will start and complete Windows startup.

 

 

No Power to PC

Normal causes:

DETAILS

If the screen powers up (screen light goes on):

If the screen draws it's supply from the PC desktop or tower but remains black, then in order of probability it is likely that::

Note: If the screen powers up, does not report memory or reports memory and then immediately hangs up, it is likely you have CPU (processor) problem.

If the screen powers up with memory reported and it goes on to report other details then waits - leave the PC alone until you get a message. It is likely that the BIOS has lost hard drive settings or the hard drive has failed (primary hard drive failure), or that the floppy drive has failed, due to bad connection of it's data cable.

If the fan is blowing hot immediately after power up, replace the Power Supply Unit.

Note: On an ATX case the main power switch (hard power) is on the Power Supply Unit with the front power switch on the PC case being 'soft power'. There is a soft power jumper on the motherboard which if not shorted by a jumper, will disable both the soft and hard power switches.

 

If the screen light goes on, the power fan is blowing, the memory is OK and the floppy power cable is on 4 pins, then it is likely to be a motherboard fault, or less likely a power output fault from the Power Supply Unit. If you are able, use a separate Power Supply Unit you know is working, attach it to the motherboard and if have no results, it's the motherboard.

If the screen does not power up (no screen light):

If it has an independent power cable check firstly check to see that it is fully in at the back of the screen, then check the cable's fuse and/or remove the cable and check it on another device e.g Electric Kettle. If the cable is OK then if you hear the drives being accessed /see the drive lights flickering, then it is likely that the screen is faulty. If the fan is not blowing, it's the Power Supply unit..

If the screen power runs from the PC Supply Unit, then firstly check that the cable is correctly in at both the PC and screen. If the cable is fitted correctly and the PC Supply fan is not running then the Power Supply fan or the whole Power Supply is faulty, if the power supply is running then it could be the screen that is faulty. Before assuming this as fact, try the screen on another PC.

Note: Never run a PC for any substantial period when you know it's Power Supply Unit fan is not working.

 

 

 Power Supply Settings

United Kingdom:

In the UK we use a 230/240v supply and 3 pin plugs, ensure that:

United States & most other counties

Countries other than the UK usually have 115v supply with a 2 pin plug. Again a normal case should only have a 5amp fuse in the power lead plug. If you have any doubts, consult your local PC shop or electrician. 

ALWAYS CHECK THE LOCAL POWER SUPPLY RATINGS BEFORE STARTING UP A PC WHICH WAS MADE/SETUP IN ANOTHER COUNTRY. For example a PC from the United States: At the back of the case you should find a power rating switch, ensure that this is flipped up to 230v for UK usage. Failure to do so WILL result in hardware failure and the cost to you of replacing components.

 

Illegal Operation Errors - bad memory

Whilst an infrequent illegal operation error may be just a 'glitch' and can usually be ignored, you should restart your PC should one occur. However, If your PC is performing these errors:

Then, the most likely cause is a fault in one of the memory modules.

You will need to take all the memory chips out and re-introduce them one by one (DIMM) or in pairs (SIMM). See below:

The SIMM type of memory is fitted into 4 possible slots, in banks of two. The slots are usually white in colour and are usually situated near the power unit. So that you do not mistake the white PCI slots for these, each slot has a clip at either end. A Bank is 2 slots which each slot having the same size of memory.

Example:

Slot 1 - 16MB

Slot 2 - 16MB

Slot 3 - 32MB

Slot 4 - 32MB

Installing/re-installing memory

SIMM memory has 72 gold pins at the card edge and a notch in the middle of the card edge. The notch in the card edge will match a gap in the middle of the slot. At one side of the chip is another notch or cut out which matches a block at one end of the slot where the clip is.

You can easily tell which way round is correct because the card edge middle notch will match exactly the middle gap in the memory slot.

Insert the chip in the centre groove of the slot at a 45 degree angle. When you feel that the memory card edge had gone into this grove, push the chip up to a vertical position. You will hear the clips at each side engage with a small clicking or snapping sound. Check each side to ensure each clip is engaged properly. Put a finger on the top edge of the memory card and if there is little or no movement laterally then the memory card is fitted correctly.

Note: slots can take 8MB, 16MB, 32MB or even 64MB (consult your motherboard manual for the maximum amount of memory, but do not mix memory size in the same bank.

DIMM memory has two notches on the card edge and two gaps in the slot. Make sure the memory card is oriented to match the slot. Ease back the two white levers at the ends of the slot. Push the card in vertically until the white levers snap into the cut-outs at each end of the memory card. If the levers are fully in the cut-outs then the memory is fitted correctly. DO NOT USE EXCESSIVE FORCE WHEN PUSHING THE CARD DOWN INTO THE SLOT.

Important experience note:

Before replacing the system unit cover, check that all cables and connectors from the motherboards and to drives etc., are correctly in place. You could have pulled out or partially pulled out a connection whilst trying to get the memory installed. When you are sure all connections and memory is fitted correctly then and only then replace the system cover. This checking only takes a few seconds which is better than having to take the cover back off and start again.

 

 

The DIMM type of memory is fitted into 1 or more possible slots. The slots are usually black in colour. So that you do not mistake any black ISA slots for these, each slot has a white clip at either end.

Usually DIMM memory is not in banks so each slot can have a different memory sized chip in it

Important Notes:

 

 

Power Cables

I have encountered problems with PCs due to the power cables used on them. The tower or desktop case power cable has a shorter head than the power cable for a screen (the head being the end that fits into the power unit of the case). If a screen power cable is used, there is a tendency for the long head to flop down and it definitely does not fit firmly. Should such a cable be moved by say the mouse or other cable, then power could be temporarily interrupted / or shorting could occur, causing damage to the system, particularly the hard drive. So, screen power cables for screens, system unit cables for system units. Also check that your system unit power cable plug fuse is 5amp only (UK standard..for other countries, check manuals or seek advise from your manufacturer).