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Can you help save “Made in U.S.A. 486” ?

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First post, by Intel486dx33

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I have a “Made in U.S.A.” VLB 486 motherboard I want to save from the recycle bin.
It is going to go in my “All USA parts 486 build”

Motherboard model - Vega VS486F-3VL
Manual:
http://www.elhvb.com/webhq/models/486vlb3/vs486f.html

Currently it does not boot up ?
No beeps?
Non responsive.
Keyboard lights do light up on power-on.

I hooked up a PC analyzer card with no readings. Non responsive motherboard.
The PSU is working fine and the motherboard is getting power.
New Dallas battery.
I tried several CPU’s( AMD, Intel Cyrix) and several Video cards( VLB and ISA ) with no video.
I get no Video output.
I double checked the display on another 486 just to make sure it is working okay.
So basically, I performed a process of elimination to rule out bad components.

Currently, I only have a video card hooked up to the motherboard.
FPM ram 16mb. and Intel 486dx2-50 CPU, 256kb. Cache.

Any Ideas ?
Can Vogons community save made in U.S.A. 486 ?

++++++++++++++++++++++++++++++++++++++++++++++++++++++
VEGA VS486F-3VL Motherboard

- AMIBIOS ID string 40-0700-006259-00101111-111192-SYMP-F
- 8-30 pin SIMM slots (1-32meg FPM DRAM)
- 3-32bit VESA Local Bus slots
- 8-16bit ISA slots
- 64k-1024k CACHE support in 8-32pin sockets + 1 TAG RAM socket
- AMI BIOS American Megatrends 486DX
- Symphony Chipset (MB-SYP243LV-V12)
- ZIF 3 CPU socket which supports these processors:
INTEL 80486SX/DX/DX2, ODP586SX
- Supports speeds of 25/33/40/50/66 MHz.
- manufactured by: ????????????? unknown

------------------------------------------------------------------------
CONNECTIONS
------------------------------------------------------------------------
Purpose Location Purpose Location
------------------------------------------------------------------------
External battery J1 Turbo LED JP23
Power LED + keylock JP20 Turbo switch JP24
Speaker JP21 32-bit VL bus slots S1,S2 + S3
Reset switch JP22

------------------------------------------------------------------------
USER CONFIGURABLE SETTINGS
------------------------------------------------------------------------
Function Jumper Position
------------------------------------------------------------------------
CMOS memory normal operation J2 1 + 2
CMOS memory clear J2 3 + 4
BIOS type select regular (27C512) JP2 1 + 2
BIOS type select flash (28F001BX) JP2 2 + 3
Battery select internal JP3 Closed
Battery select external JP3 Open
Factory configured - do not alter JP12 Closed
Factory configured - do not alter JP15 Open

------------------------------------------------------------------------
DRAM CONFIGURATION
------------------------------------------------------------------------
Size Bank 0 Bank 1
------------------------------------------------------------------------
1MB (4) 256K x 9 NONE
2MB (4) 256K x 9 (4) 256K x 9
4MB (4) 1M x 9 NONE
5MB (4) 256K x 9 (4) 1M x 9
8MB (4) 1M x 9 (4) 1M x 9
17MB (4) 256K x 9 (4) 4M x 9
16MB (4) 4M x 9 NONE
20MB (4) 1M x 9 (4) 4M x 9
32MB (4) 4M x 9 (4) 4M x 9

------------------------------------------------------------------------
SRAM JUMPER CONFIGURATION
------------------------------------------------------------------------
Size JP8 JP9 JP19 JP25 JP26
------------------------------------------------------------------------
64KB 1 + 2 1 + 2 1 + 2 1 + 2 1 + 2
256KB 1 + 2 1 + 2 2 + 3 2 + 3 2 + 3
1MB 2 + 3 2 + 3 2 + 3 2 + 3 2 + 3

------------------------------------------------------------------------
SRAM CONFIGURATION
------------------------------------------------------------------------
Size Max Cachable Cache TAG
------------------------------------------------------------------------
64KB 8MB (8) 8K x 8 (1) 8K x 8
256KB 32MB (8) 32K x 8 (1) 32K x 8
1MB 64MB (8) 128K x 8 (1) 128K x 8

------------------------------------------------------------------------
CPU TYPE CONFIGURATION
------------------------------------------------------------------------
CPU JP7 JP10 JP17
------------------------------------------------------------------------
80486SX Open 2 + 3 Open
All others Closed 1 + 2 Closed

------------------------------------------------------------------------
CPU SPEED CONFIGURATION
------------------------------------------------------------------------
Speed JA1 JP4 JP5 JP6 JP11
------------------------------------------------------------------------
25/50iMHz 2+3 2+3 Open Closed 2+3
33/66iMHz 2+3 2+3 Closed Open 2+3
50MHz 1+2 1+2 Open Closed 1+2

------------------------------------------------------------------------
Speed JP13 JP14 JP16 JP18
------------------------------------------------------------------------
25/50iMHz Open Closed Open Open
33/66iMHz Open Closed Open Open
50MHz Closed Open Closed Closed

===================END OF DATA ON VEGA VS486F-3VL======================

+++++++++++++++++++++++++++++++++++++++++++++++++++++++

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Last edited by Intel486dx33 on 2019-04-14, 16:52. Edited 7 times in total.

Reply 1 of 41, by Keith1212

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Possibly a bad bios since no code is shown.

Commodore PC-10
NEC 8088 Processor - 8087 Math CoPro - 640k Ram - DOS 3.3
IBM Aptiva 2144-M51
Socket 7 Pentium 166MHz MMX - 128MB Ram - Voodoo 1 - Windows 95
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Reply 2 of 41, by Dominus

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What is it with the topics today that are obvious moderator bait 😉

Windows 3.1x guide for DOSBox
60 seconds guide to DOSBox
DOSBox SVN snapshot for macOS (10.4-11.x ppc/intel 32/64bit) notarized for gatekeeper

Reply 3 of 41, by dkarguth

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Is the clock oscillating? There should be lights on the POST card that flash if the clock is running.

"And remember, this fix is only temporary, unless it works." -Red Green

Reply 4 of 41, by Intel486dx33

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Keith1212 wrote:

Possibly a bad bios since no code is shown.

The motherboard does have a jumper to use regular bios ( 27c512 ) or flash bios 28f001bx ).

I have it set to use regular bios.

Reply 5 of 41, by Intel486dx33

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dkarguth wrote:

Is the clock oscillating? There should be lights on the POST card that flash if the clock is running.

Yes, when I turn on the computer the PC analyzer card lights to blink for a couple seconds and then stop with 5 lights turned on and 3 lights turned off.
I do not know what each light on the PC analyzed card represent.

Reply 6 of 41, by dkarguth

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The lights should flash continuously if the clock is oscillating. There should be two lights on the card that alternate blinking the entire time the computer is on. If they stop for any reason, that means the clock has stopped. Do you think you could post a short video of what the computer is doing?

"And remember, this fix is only temporary, unless it works." -Red Green

Reply 7 of 41, by Intel486dx33

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Okay, I am waiting for YouTube to approve video.
In the mean time. I have the Dallas Clock battery removed. Does it need to be installed for the motherboard to work?
If so which way do I install it?
It is a new battery but it does not have any notch indicator to indicate in which way to installing.
Do I just install it with the lettering right side up ?
The notch on the battery connector on the motherboard is on the left.
But the battery itself has no notch to indicate in which way to install it.
The notch on the motherboard connector is indicated by the red mark on the diagram.

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Reply 8 of 41, by Deksor

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As it also stores the CMOS settings, you probably need it to POST.

Trying to identify old hardware ? Visit The retro web - Project's thread The Retro Web project - a stason.org/TH99 alternative

Reply 10 of 41, by Deksor

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Look here, page 20 the "EDIP" model : https://datasheets.maximintegrated.com/en/ds/ … 5-DS12C887A.pdf

Trying to identify old hardware ? Visit The retro web - Project's thread The Retro Web project - a stason.org/TH99 alternative

Reply 11 of 41, by Intel486dx33

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Okay thanks, Let me test the battery with a meter and then install it I will see if anything changes.

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Reply 12 of 41, by Vynix

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Maybe a long shot but have you tried using the 2nd BIOS (since you mentioned this mobo has a 2nd bios... It's possible that the main one got "corrupted" somehow)?

Proud owner of a Shuttle HOT-555A 430VX motherboard and two wonderful retro laptops, namely a Compaq Armada 1700 [nonfunctional] and a HP Omnibook XE3-GC [fully working :p]

Reply 13 of 41, by Intel486dx33

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Okay, I put another new Dallas battery in the motherboard. I tested it first with a meter to make sure it was working okay.

No luck. Same results.
The motherboard is unresponsive.
I hooked up the IDE controller to see if the motherboard was seeking the drives but it is not.
It just performs a keyboard check and then stops working.
No video and no beep error codes.
I tried both bios jumper setting and still the motherboard is unresponsive.

Reply 14 of 41, by Deunan

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Keyboard LEDs will blink once on their own as long as power is applied - there is another MCU in there that does that as a part of it's own init sequence. So that's is no indication of any motherboard activity. In fact, unless you have some serious ISA slot issues, the test card not showing any codes at all suggest the mobo is not running.

Since it can be re-jumpered to a different BIOS chip, double check that the settings are applied correctly. The mobo should at least init the CPU and only then complain about the missing parts. So remove everything, cards (except the test one), RAM, even RTC chip, disconnect any and all cables other than PSU ones. And I mean any cables, turbo LEDs and whatnot as well. Then power up and see if you get any codes on the test card.

If not, that's bad and doesn't bode well. Put in a different, 5V 486 CPU with no clock multiplier, jumper it to lowest speed you can (20 or 25MHz), try again. If there's no codes still I think you should give up on this mobo.

EDIT: I forgot, take it out of the case! Test just the mobo+CPU, PSU and test card on a desk.

Reply 15 of 41, by Intel486dx33

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Here is a video of what is happening:
https://drive.google.com/file/d/1a6s66EZ1GJos … iew?usp=sharing

I just noticed that who ever had this motherboard before removed the original Dallas and barrel battery.
It should post without a barrel battery right ?

Is there anywhere where I can get a bios ROM for this motherboard ?
Also it looks like a component may be missing next to where the barrel battery was.
Maybe the barrel battery burst and leaked on the motherboard damaging a component.

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Reply 16 of 41, by Deksor

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The DS12887A has a integrated battery already, so the board must have come in two "flavours", one with a dallas chip without internal battery and one with it.

Trying to identify old hardware ? Visit The retro web - Project's thread The Retro Web project - a stason.org/TH99 alternative

Reply 17 of 41, by Intel486dx33

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I think I am going to take out the motherboard and perform a thorough inspection of this board.
I am trying to rush this build thinking there is nothing wrong with this board. i bought this board because the seller said it was working. But obviously something happened to this board and it was not working.

Reply 18 of 41, by Intel486dx33

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Update:

Okay, I put another vlb 486 motherboard in the case to test and it also does not work.
Does the same as the other one. No video and only keyboard check lights.
It stops working after keyboard lights check. Just like the other Motherboard.

Could it be there is something wrong with my power supply or AT adapter ?
I am using a standard ATX power supply and this adapter.

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Reply 19 of 41, by Vynix

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Most likely the mobo requires -5V, which most ATX power supplies seems to ommit, unless your adapter does have a regulator for the negative 5V, I have a hunch that your problem might be caused by that.

Another hypothesis albeit an unlikely one would be that something is shorting the mobo. Try also breadboarding the mobo (running it outside the case on a cardboard sheet to avoid any shorts) to rule out something potentially shorting it.

Although I'm certain that the ATX to AT adapter that you have is to blame for this issue.

Edit: looking at the picture of your adapter, it does not seem to have a voltage regulator for the -5V.

Proud owner of a Shuttle HOT-555A 430VX motherboard and two wonderful retro laptops, namely a Compaq Armada 1700 [nonfunctional] and a HP Omnibook XE3-GC [fully working :p]

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