Disclaimer. Use these diagnostic and repair routines at your own risk. A Gathering Place or NW Computer jbstone@usa.net will assume no responsibility for damage or injury incurred from using these methods.

Symptom:

Start up problems
1. System does nothing, no lights no fan, no power.
2. System lights come on but no video display.
3. System lights and video come on but system hangs up at start up (POST) and won't boot to Windows.
4. System boots O.K. then hangs and message "Can't find boot record" appears.
5. System turns on but no Harddrive activity (light stays off.)
6. System turns boots up but an "incorrect Memory size" or Parity Error" appears on the monitor.
7. System boots up but one or all of the following error messages appear:
A. Memory address line failure at xxx read yyy expecting zzz
B. Memory data line failure at xxx read yyy expecting zzz
C. Memory high address failure at xxx read yyy expecting zzz
D. Memory logic failure etc
E. Memory odd/even logic failure etc.
F. Memory read/write failure etc
xxx refers to the address yyy refers to what is read back from that address and zzz is what was expected.

8. System boots up but "ROM error" appears on the monitor.
9. You hear a series of 'beeps' but no error code is displayed.
10. The Start up sequence (POST) stops at some code, (and probably hangs up)

Symptom 1. System does nothing, no lights, fan or power.

Make sure that the system is plugged in. If you are familiar with voltage testing procedures, test the AC voltage at the end of the cord that plugs into the computer make sure that it is between 110v and 120v but use extreme caution! Serious injury or damage can result from improper test procedures. Protect yourself from accidental electrocution. If the AC input level is acceptable then remove the case from the computer and carefully check that the power connections from the supply to the motherboard and drives are all tightly connected and not broken. Next disconnect the power lead from one of the floppy drives. Set your multimeter for D.C. voltage readings. Place the ground lead on pin 2 of the connector and the positive lead on pin 1. Power up the unit and read the voltage, it should be 12 v + next place the ground lead on pin 3 of the same connector and the positive lead on pin 4, the reading should be 5v + If these voltages are low or missing replace the power supply. If they are present at their normal value, move on and turn off the unit, then disconnect the power connector to the motherboard. There should be a legend on the actual supply stating the output voltages for each of the leads, if not then locate the black lead at the connector and connect your negative probe there. You should be able to read either 12v or 5v at each of the other leads. If any of these readings are low, replace the supply.

Symptom 2. Light on the front panel comes on but no display.

Check to make sure that your monitor is plugged in and working properly, it should have an indicator light that is lit. If possible check the monitor on another computer. Make sure that the data cable that plugs into the back of the computer is intact and not cut or broken. Inspect the connector and make sure the pins are straight and undamaged and all the same height and not pushed in. Make sure the video card is in the slot firmly and that the retaining screw is firmly in place. Make sure the female connector on the board is free of debris, corrosion and obstruction and is mounted firmly on the card. If the reset light remains brightly lit, there may be a problem with the power supply, the computer is waiting for a "power good" signal to continue the boot sequence, check the power supply (see symptom1) If there is still no video, replace the video card and try again.

Symptom 3. System lights and video come on, but system hangs at POST and won't boot to windows.

This can be a symptom of numerous problems which need to be broken down by category.

a. Are there a series of beep codes? (See 'Troubleshooting Beep Codes' in the Troubleshooting section of this department.)
b. Is there an error code displayed on the screen? (See the error code symptoms and keys in this section.)

One of the most common causes of hang up at the start sequence (POST) is an incorrect CMOS setting. The CMOS is the set of start up instructions that tell your computer what hardware and accessories are installed and how to deal with them. These instructions are kept in the CMOS's memory by using a small back-up battery, If for any reason this battery loses voltage or just gets old and fails, then the system configuration will be lost and the system will hang at the post. Replace the battery and reset your drives and system data. If you are not familiar with CMOS operation you should not attempt modifications to the setup.
Most CMOS have a "Restore defaults" setting in them. If you are not an advanced CMOS user but have reason to suspect the CMOS is a fault, you can often use this function to get the system working. Pressing the 'Delete' key (often several times) at power on accesses most CMOS set-up programs. Be careful! Incorrect CMOS setting can cause your system to stop operating completely.

Symptom 4. System boots O.K. then hangs and the message "Can't find boot record" appears.

This particular error code usually indicates a problem with the Harddrive. After the initial POST, the system asks for instructions from the harddrive to continue the boot process, and if there is a problem communicating with the drive, or if the (System) instructions are missing this message will appear.
First try to boot the computer using a start up disk or DOS disk #1 which contains the necessary (DOS) instructions (Command.Com, I/O.SYS, and MS-DOS SYS. It is best to make sure that you are Using a start up disk with the same version of DOS as the computer. If the computer will boot from the floppy, try switching to the 'C:\> prompt, if you can access the harddrive then check and make sure that your system files are in place (COOMAND.COM, I/O.SYS. MS.DOS.SYS) you will probably have to change the properties in the view tab to 'view all files' as the I/O.SYS and MS-DOS.SYS are normally hidden files. If these system files are in place and the harddrive is working properly then check the boot-up sequence located in the CMOS and make sure that the C:/ drive (or whatever drive contains the boot record) is in the sequence and is listed and the number 2 device to search.

Symptom 5. System turns on, but there is no harddrive activity (light stays off.) If this problem begins suddenly and nothing new has been added or no new software has been recently installed, then turn off the system and turn it back on, and listen very carefully to the case, you should be able to hear the harddrive clicking rapidly inside. If no sound is present and no harddrive light comes on, then first check the CMOS configuration and make sure that the drive is configured correctly. If you are not familiar with CMOS operation, do NOT attempt this procedure. First reboot the computer and press the DEL key until the CMOS program comes up. Look for: “Standard setup” or “Drive configuration” it may be listed under this or a similar title, the proper section will list the harddrive, floppy’s, and the CD-ROM in the same section. After the setup parameters are located check that the listing is the same as your harddrive. If you aren’t sure what size of drive you have then open the case and look at the label, many drives have the size and configuration information listed on a label on the drives case. If not then read the model number and manufacturer name and call a computer repair shop who has a reference guide (most shops do) or see your local library’s reference section. Determine if the drive is the same as the one installed in the CMOS, if your drive is a newer one, larger than 2 Gigs, your “user setting” may be set at “AUTO” in which case a Dynamic overlay program may be controlling the drive. (this is a program which fools the system BIOS into letting it run larger harddrives) This overlay program should pop up at the initial start up, and say something about managing the “BIOS” (like: “EZ BIOS is managing harddrive controller 1” etc) If you already know which dynamic overlay program you are using, check it to make sure it is functioning correctly. It may need to be reinstalled. If the drive is functioning correctly but still won’t boot the system files, try running SCANDISK from the DOS prompt or some other disk utility program, there may be damaged files which are preventing access.

Symptom 6. The system boots up but an “incorrect Memory Size” or “Parity Error” appears on the monitor.

This is a common error code when the user has recently added additional RAM memory to the system or a memory IC has failed. These are the (normally) 72 pin plugin chips that determine your system’s RAM. (note, you must use static protection when working with SIMMs or other memory IC’s. Ground your skin to the chassis of the computer by any means necessary.) ( I use an alligator clip jumper wire to my metal watch band, and the other end to the metal of the power supply chassis.)
Make sure that the SIMM’s chips are properly seated in the sockets and facing the proper direction. Note that there is a notched end on each one of the chips and that it must corespond to the notch in the socket for proper operation. All chips should install easily without forcing and they should all face the same direction.
Next take a known-good SIMM and step thru each occupied SIMM socket until the problem disappears. You may need to alter the CMOS setup as you alter memory settings in the computer as the wrong setting can cause problems during system initialization.

Symptom 7.

You might see any one of the following general RAM errors a. Memory address line failure at XXXX, read YYYY, expecting ZZZZ b. Memory data line failure at XXXX, read YYYY, expecting ZZZZ c. Memory high address failure at XXXX, read YYYY, expecting ZZZZ d. Memory logic failure at XXXX, read YYYY, expecting ZZZZ e. Memory odd/even logic failure at XXXX, read YYYY, expecting ZZZZ f. Memory parity failure at XXXX, read YYYY, expecting ZZZZ g. Memory read/write failure at XXXX, read YYYY, expecting ZZZZ Each of the errors shown are general RAM error messages indicating a problem in base or extended/expanded RAM. The code XXXX is the failure segment ad-dress-an offset address might be included. The word YYYY is what was read back from the address, and ZZZZ is the word that was expected. The difference between these read and expected words is what precipitated the error. In general, these errors indicate that at least one base RAM IC or at least one SIMM has failed. A trial-and-error approach is usually the least expensive route in finding the problem. First, reseat each SIMM and retest the system to be sure that each SIMM is inserted and secured properly. Rotate a known-good SIMM through each occupied SIMM socket in sequence. If the error disappears when the known-good SIMM is in a slot, the old SIMM that had been displaced 'is probably faulty. You can go on to use specialized SIMM troubleshooting equipment to identify the defective IC, but such equipment is rather expensive unless you intend to repair a large volume of SIMMs to the IC level. If the problem remains unchanged even though every SIMM has been checked, the error is probably in the motherboard RAM or RAM support circuitry. Run a thorough system diagnostic if possible, and check for failures in other areas of the motherboard that affect memory (such as the interrupt controller, cache controller, DMA controller, or memory management chips. If the problem prohibits a software diagnostic, use a POST board and try identifying any hexadecimal error code. If a support IC is identified, you can replace the defective IC, or replace the motherboard outright. If RAM continues to be the problem, try replacing the motherboard RAM (or replace the entire motherboard), and retest the system.

Symptom 8. System boots up but “ROM ERROR” is all that appears on the screen.

This is the error code that usually indicates that there are no system files on the harddrive, (COMMAND.COM, I/O SYS, MS-DOS.SYS) the computer scans the drive looking for further bootup instructions and when it dosen’t find them it brings up this error. This sometimes happens when you format a drive and forget to add the ”/s” command, after the format command. Try reformatting the drive with the command: format c:\ /s

Symptom 9. You hear a series of ‘Beeps’ but no error code is displayed.

Any beep code other than just the short ‘beep’ at the post indicates a serious problem. See the “Troubleshooting beep codes” article in this section.

Symptom 10. The system start up sequence (POST) hangs up on some code.

Your system BIOS (Basic Input Output System) has a problem. POST codes vary widely for different BIOS manufacturers first you need to determine what type of BIOS is installed in your computer. In order to do this you must open the case and look at the IC chips installed on the motherboard the traditional BIOS chip is a 28 pin (per side) dual in line IC, mounted in a socket which allows it to be removed and replaced. This chip may have a small square or round window in the middle and should have a sticker on the top which tells exactly what type of BIOS chip it is and the manufacturer . Armed with this information, go the BIOS section of this website and look under “BIOS manufacturers” and see if you can match the chip to the manfacturer on the list. Since there are so many types it should be quicker and easier to contact the manufacturer’s website and look up the appropriate beep code.