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486 Turning on, I hear the disk drives start, then nothing

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Smack2k

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Got my 486 up and running (kind of) with power...

Now, when it starts, I hear the machine come on, the MOBO starts to do its thing, I hear the CD-ROM / [2] Floppy drives make their starts and then it just sits there running...and I dont get any video out of my VGA card...

I used a monitor that I know worked on a 286 so I'd imagine it would work on a 486...but still, no video on screen...

What to try next?

GMB-486UNP MOBO

Trident grapics card
 
Reseat ram and cards, clear CMOS, disconnect everything from the motherboard except video card, keyboard, and minimal amount of ram. Also might want to test the PSU.

EDIT: Forgot to ask, does the system beep at all?
 
No beeps at all...will do the other tests and let you know.

The PSU seems to work as the thing does power on....not sure what that says!!
 
There's battery leak?

This system was working in past?

The speaker is good and correctly connected?

Put a Hard Drive as dummy load (only connect the power molex, not the flat).

Could you post a pic of the motherboard connections?

The jumpers are in correct positon?

The CPU is getting warm?
 
Will answer all of these for you later with details..

Thanks for the help...will let you know

Again, appreciate it!
 
Common causes for a refresh failure include incorrectly inserted RAM, bad RAM socket, excessive bus speed, or incorrect wait states. I would try making sure that only one RAM bank is filled (with however many sockets that is). If it fails in one bank, try filling just one different bank. If any RAM socket feels loose, then you may have to ignore that bank or resolder the RAM socket in place.

For a complex set of troubleshooting directions, look at http://www.pcguide.com/ts/x/sys/beep/amiB1-c.html
 
Tried just 1 RAM stick - no luck - 1 beep

Tried filling Bank 0 - no luck - 1 beep

Tried filling Bank 1 - no luck - 1 beep

Checking out that guide...I was testing with Video Card / RAM / MOBO / Keyboard / Monitor...

If this ends up bad MOBO...anyone got a decent 486 MOBO they'd like to get rid of?!!

Next stop is jumpers..will clearing CMOS help?
 
Last edited:
Smack2k said:
Tried just 1 RAM stick - no luck - 1 beep

Tried filling Bank 0 - no luck - 1 beep

Tried filling Bank 1 - no luck - 1 beep

Checking out that guide...I was testing with Video Card / RAM / MOBO / Keyboard / Monitor...

If this ends up bad MOBO...anyone got a decent 486 MOBO they'd like to get rid of?!!

Next stop is jumpers..will clearing CMOS help?
Click to expand...

Looks like this is your board. Check every jumper! Also clean your RAM sticks, and the sockets.
 
Checked all the jumpers on the board, all but one were set correct...

I fixed that one...still 1 beep!!

Thinking its shot as I am out of ideas....
 
I have a bead on one for 10 dollars that is just the MOBO on Ebay...if that fails, then I will be contacting Cudasales in the morning...

Thanks...
 
Are there any electrolytic capacitors? If so, it's possible some of them dried out. That can cause RAM refresh failures. (Tiny caps are not immune to this problem.) After all, it's assumed those caps are upwards of 13 years old.
 
Did you try with another video-card? If you hear the drives initializing, it seems that the board is working and for some reason you don't get video
 
I see where you swapped your RAM and tried a few different configurations. If possible, try altogether different RAM. Also, while wringing the board out, use only a minimum hardware configuration; i.e. video card only.
 
Not too few BIOSes produce one beep at startup without any error condition met. If it proceeds to seek on the floppy drives the RAM should be functional.

Does the monitor make syncing noises? Your power supply provides -5V? Many older VGA cards need -5V for the video DAC. The other option is your video card or only the DAC is dead.
 
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