SouthMissDJ wrote:

I recently found this motherboard in a system being thrown away. I took this photo to document all of the jumpers before giving the board a bath. The settings pictured are for the Intel 486DX2-66. I have since upgraded CPUs to the AMD 5X86-133, an undocumented processor for this board. The closest settings get it to either 120 or 150 mhz. Good luck with yours!

what jumper setting did you use to set it at 120mhz or 150mhz
(im talking about an AMDX5 133mhz cpu)

because that is not tocumented anywhere.

Hi
What should go there in RN13, RN14, RN16?
Is it some resistors leader?

RN=resistor network

PcBytes wrote on 2022-08-09, 21:51:

RN=resistor network

Ok, but could You measure values?

I don't have the board but figured it would be one of those SIPP styled resistor networks.

Although, most of the photos I see over Google show them as being left empty, except this one which appears to have what I think is a dummy resistor network (000J means 0 ohm, I guess?) so probably those sockets are unused altogether.

Yes FIC used 0 ohm arrays instead of jumpers on many 486 boards, somewhere here is a post about them showing 0 ohms and their layout.
Basically there are 5 loops of wire inside pins 1-2, 3-4, 5-6, 7-8,9-10.....
like in this topic: Thoughts on how to go about fixing this?

Horun wrote on 2022-08-09, 22:45:

Yes FIC used 0 ohm arrays instead of jumpers on many 486 boards, somewhere here is a post about them showing 0 ohms and their layout.
Basically there are 5 loops of wire inside pins 1-2, 3-4, 5-6, 7-8,9-10.....
like in this topic: Thoughts on how to go about fixing this?

Thanks, That would be easy to make.

DeafPK wrote on 2018-02-09, 13:03:

I am currently working on one of these mobos - it goes through its POST, it can auto detect a 500 meg HDD over a Goldstar ISA I/ […]
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I am currently working on one of these mobos - it goes through its POST, it can auto detect a 500 meg HDD over a Goldstar ISA I/O controller, but it won't boot. Not from anything. The floppy does not search for disks after POST but it reacts during the POST. CMOS battery has been replaced with CR2032 mod and it works.

What happens is POST does its things, seemingly successful, then the screen clears and there is just a single flashing underscore in the top of the screen, like _
I gave it 15 minutes once, no gain. The stuff connected to the system are parts known to be OK. I have to say that the mobo was pulled from a dumpster and I've cleaned it with isopropanol alcohol and had it drying for months. Who knows really what is has been through.. I just don't feel like giving it up when I'm getting so close.

BTW if anyone still wonders, J7 gives a message before POST that BIOS passwords are disabled.

I know it's been a while but just to add some clues for future readers: I had the *exact* same setup and symptoms, and eventually found the ISA FDD/HDD controller to be the culprit. Exchanging it for a Winbond ISA controller card solved the issue on the spot.

Finally the full user manual for 486-GVT-2 is available on TRW site. Unfortunately it contains no descriptions of the jumper settings for any of the AMD 486 CPUs.