building an old 486 from bitz

I know this probably isn't the answer you're looking for, but it sounds to me like that hard disk controller is bad. There is nothing you can do to repair it. Replace it and chances are everything else will work just fine. If I'm understanding your question correctly, the system is booting intermittently. Try this: boot without the hard disk controller installed. If it boots reliably, then you can be sure that controller is junk. Another thing to check: look very carefully (with a flashlight!) at how the cards are seating on the motherboard. Are all of the pins on the edge of the card fitting snugly into the slots? Also (although I doubt thsi will help) try cleaning the contacts on all your cards with a pencil eraser and then wiping them with a clean piece of cloth (do not touch the contacts with your fingers!) This is an old technician's trick for cleaning metal edge contacts.

Try this:
1) Remove everything from motherboard except video card and RAM.
2) Remove all power supply leads except the motherboard's power connector.
3) Plug the monitor in and power up the computer.

Anything on the screen now?

Regards,
Ralph

thanx impaler233, but thats not what i was looking for.

Yeah, Ralph, ive done that, and both video cards i have dont work, but the thing is that when i brought the parts, i tried putting it together at the guys house, and it didnt work. Then when i got it home, i tried again, and it worked. Everything was working (cept the HDD controller, but the boot up msgs were comming up on the monitor), then i decided to try the 386 motherboard i had. I put that in, it didnt work, so i put the 486 one back in, now it doesnt work. Is it posible i fryed it during the change over or sumthin??? how do i test for that??

thanx

Try this:

Take out CPU and memory.
Put cpu in again (this helps make sure it's seated correctly)
Plug speaker onto speaker connector (so you can hear it do the POST beeps)
Connect power and turn on. You should get the 'no memory' beep-beep-beep or constant.
 - if not, see if you check your jumper settings for CPU. See if you can try another CPU.
 - if it beeps, turn off power and put memory in. Turn on.
You should get the OK beep (single beep).
 - if not, try putting memory in different slots (you may have a failed or dirty SIMM slot)
 - if it beeps, turn off power and put graphics card in. Turn on.
You should get display.
 - if not, try a different slot for graphics card. Check the card in another PC.
 - if you get display, turn off power ...

You get the idea, build it up bit by bit until it fails, then you know what caused the failure.
I would suspect you may have lost a jumper off the board (486 boards have so many!), during transit, or one of your cards/motherboard has got static damage.

If you can narrow the problem down logically using the POST beeps (that's what they are there for!), you should be able to determine what needs replacing. If it is your I/O card, you can pick them up for about £3 ($5).

phrost_byte,
I'd pull the motherboard  out of the chassis.
Perhaps you'll find that a mounting screw in the case is shorting the motherboard to ground somewhere.  
Try suggestions listed in my last comment with your board on the table top, power supply nearby.
I neglected to mention the keyboard before.  Connect it for your test as well.
Its LEDs should all flash once, indicating reset at powerup.  
Let me know how it goes.
Ralph

thanx guys, i put the speaker in, and took the motherboard of the case, and set it all up on a table. all i had in the board was the ram (all 8 slots filed) and keyboard. When i powered up, the keyboard lights (all three) flashed once, then i got three beeps from the speaker. so i altered the ram i had in there, i put only 4 in, but i keep getting two high pitched beeps, then 8 low beeps from the speaker (and all 3 keyboard lights flash), no matter which way i put the 8 different ram boards i have in the slots.

i think it was being shorted out. I put the video card in, and it boots up, but now... when i put the HDD controler card in, i get an error saying keyboard error, press f1   and when i put my HDD details (heads, sectors, cyls, etc) in the CMOS setup, it doesnt come out right in the size to what it actually is, and it wont continue booting..

thanx

Adjusted points to 20

Well, lets see.....
1) Apparently when you got the beep code, the video card was not installed. (8 beeps = video error)
2) Keyboard errors at boot-up usually indicate that a key has been pressed, (maybe stuck?) or connecter not firmly installed.
3) Insure that the HDD is cabled correctly, with master/slave jumper set properly.(Colored stripe on edge of data cable is oriented towards pin-1 at the drive and also at controller end.)
4) Has the HDD operated with this controller before?
5) Will your BIOS auto-detect the drive?
6) Don't forget to save the HDD settings when exiting the CMOS setup.
Let me know how you're progressing, and if you need more.
Ralph

ralph,
2 - no keys were pressed or stuck, that error only comes up when i have the HDD controler in, and i have tried 2 set the HDD.
3 - yep, its plugged in properly, but theres no jumpers next to the ribbon cable or the power supply, theres some at the back, but they're not labeled
4 - no, its the same controler that came with the 486 board, but the HDD drive is a different one. The heads on the HDD crashed on the drive that originally came with it. And, ive tried another controler (with the HDD that was with that originaly) and that doesnt work either.
5 - nup, bios wont autodetect it
6 - yep, i saved the settings.

1) Tell me the brand/model number of your hard drive.
2) Unplug hard drive's data cable from the controller.
3) Do you still get that keyboard error?

Ralph

k,
1 - Conner, CP30104H (121M) and i have tried a Conner CFS1275A (1.2G)
2 - k, now it holds on the wait.... bit, and comes up with 2 beeps, and says - HDD controller failure, Press F1 to resume.
if i have the data cable in, it does the same as above. And i get the same results for both HDDs i use, and for both HDD controler cards i have. (i dont get the keybaord error anymore, because i did have a key being held down, i didnt notice it at first, coz it was a lead that i had mnoved)

OK on the keyboard error!
We're getting there....  
1) Does controller card contain devices other han HDD & FDD? (Serial, LPT, game, etc.)
2) Are those devices enabled in BIOS and listed correctly on screen as the computer boots up?
Ralph

1 - yeah, it has a game port, com1, com2, and printer port, but none of those are plugged in, only the HDD one.
2 - only the HDD, and yep

I don't quite understand your response in 2) above.

1) Do you mean that COM & LPT ports are not enabled in BIOS, or not listed at bootup?
Simply unplugging the cables does not disable those ports.  If they are on the card, you must configure jumpers to disable them.
Now, if those jumpers have been incorrectly set, perhaps the ones for the hard drive are, as well.
You will need documentation to determine that.
The master/slave jumpers may not be set correctly, causing BIOS to fail to detect the hard drive.

2) Are they?
Try this site for the drive jumper configuration:

http://www.blue-planet.com/tech/no-frames.html

3) Does your floppy drive work okay?
(It is also jumpered on that card.)

Let me know how it's going.....
Ralph

i have no master/slave set on the hdd, and i went to the page, and they do have my drive, but i dont understand which jumpers to put on to set master/slave on my hdd.

3 - i havent tried my floppy (will do tho)

hey ralph, i got it all working fine now!! :) i had 2 set the jumpers to master on the HDD, and everything works. Thank u HEAPS for all youre help!! ... can u just type sumthin in the answer (not comment) box so i can give u ya points. Thanx again btw :)

Adjusted points to 40