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ASUS VL/I 486SV2G v2.0 problem (converted to X4) - Solved!

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First post, by airs

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Hi all, I'm looking for some assistance troubleshooting a PS2 mouse issue with this board. I'd really love to get it working as it's been my holy grail for a long time!

History

  • Received board with destroyed C10 capacitor - perhaps power supply was connected incorrectly?
  • Replaced C10 with 50v 10uf cap (orange color) - my understanding is that the higher voltage rating is OK
  • Tested with Intel DX33 - SUCCESS, but no keyboard detected (IBM Model M PS2)
  • Swapped keyboard to Dell AT101 PS2 - SUCCESS
  • Ordered new EEPROM, programmed it with latest BIOS, replaced existing EEPROM
  • Performed X4 conversion (thanks d0pefish!)
  • Tested with Intel DX33 and AMD Am5x86 133 P75 - SUCCESS
  • Ordered Startech PS2 bracket, used multimeter to move pins to correct locations
  • Tested with Microsoft PS2 Intellimouse - FAIL - no error about keyboard on boot, I can get into BIOS with Delete key but then keyboard does not work. Keyboard also does not work at DOS prompt and mouse is not detected (cutemouse in autoexec)

Tests

  • Multimeter shows 5v at PS2 mouse header
  • Multimeter shows continuity between Clock and Data pins on PS2 mouse header and pins on AMIKEY-2
  • Logitech MX500 connected with USB -> PS2 adapter - LED on bottom of mouse lights up red, but no mouse detected
  • Microsoft Basic Wheel mouse connected with USB -> PS2 adapter - LED on bottom of mouse does not light up, no mouse detected
  • Logitech G403 connected with USB -> PS2 adapter - LED on bottom of mouse does not light up, but no mouse detected
  • Using a modern HP PS2 keyboard instead of the Dell AT101 has same result as tests above

Does anyone have ideas about further tests to run? Perhaps the mouse and keyboard aren't getting enough power? I'm wondering if more than just the C10 capacitor was damaged, but I'm not sure how to check for that. Physically the board looks ok to me, but I'm attaching some high resolution photos of the board in case I've missed anything.

Thanks for your time!

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Last edited by airs on 2019-11-07, 18:43. Edited 4 times in total.

Reply 1 of 13, by airs

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Reply 2 of 13, by Horun

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Everything looks good. J7 is set correct. Are you sure you have the PS/2 port wired correct ? I have a pinout from Asus that shows their 6/8 pin PS2 port for most 486 and pentiums like this:
1 2 3 4 : 1 =Gnd, 2 = Data, 3 = NC, 4 =VCC, 5 = Clk, 8 =NC
0 0 0 0
0 - - 0
5 6 7 8

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 3 of 13, by airs

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Horun wrote:
Everything looks good. J7 is set correct. Are you sure you have the PS/2 port wired correct ? I have a pinout from Asus that sho […]
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Everything looks good. J7 is set correct. Are you sure you have the PS/2 port wired correct ? I have a pinout from Asus that shows their 6/8 pin PS2 port for most 486 and pentiums like this:
1 2 3 4 : 1 =Gnd, 2 = Data, 3 = NC, 4 =VCC, 5 = Clk, 8 =NC
0 0 0 0
0 - - 0
5 6 7 8

Yep, triple checked my wiring.

Reply 4 of 13, by Doornkaat

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Have you tried bridging the fuse at the top left corner?
This fuse is meant to prevent overcurrent from hot plugging keyboard or mouse. Sometimes it semi breaks, creating enough resistance that some devices work and some don't.
If bridging the fuse helps don't forget to replace it with a new one. 😀
Oh and of course no hot plugging mouse or keyboard especially while the fuse is bridged. 😁

Reply 5 of 13, by airs

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Doornkaat wrote:
Have you tried bridging the fuse at the top left corner? This fuse is meant to prevent overcurrent from hot plugging keyboard or […]
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Have you tried bridging the fuse at the top left corner?
This fuse is meant to prevent overcurrent from hot plugging keyboard or mouse. Sometimes it semi breaks, creating enough resistance that some devices work and some don't.
If bridging the fuse helps don't forget to replace it with a new one. 😀
Oh and of course no hot plugging mouse or keyboard especially while the fuse is bridged. 😁

Thanks for the reply - do you mean bridging it like this?

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Reply 6 of 13, by Doornkaat

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Exactly - assuming those are both ends of the same yellow wire.
(Although I would have just soldered a small wire in parallel but your approach is probably more professional. 😁 )
Any luck with this so far?

Reply 7 of 13, by airs

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Doornkaat wrote:

Exactly - assuming those are both ends of the same yellow wire.
(Although I would have just soldered a small wire in parallel but your approach is probably more professional. 😁 )
Any luck with this so far?

No luck - powered it on with the bridge in place but no change in behavior 😐

Reply 8 of 13, by Doornkaat

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Too bad. 😒
One more thing: Does your BIOS support PS/2 mice and have you enabled IRQ 12 for mouse in BIOS under Power Management Setup?

Reply 9 of 13, by airs

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I think it supports PS2 mice since the BIOS I programmed was the latest one from Phil’s website. I did enable IRQ 12 in power management.

I ordered a replacement AMIKEY-2 chip yesterday. My plan at this point is to use a logic analyzer and oscilloscope connected to the ps2 header to try and capture what’s happening. Based on that I may desolder the AMIKEY-2 and replace it. I’m also considering recapping the entire board. Uggggh.

Reply 10 of 13, by airs

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Still haven't solved this unfortunately. I find it interesting that I can enter BIOS by pressing the delete key, but then the keyboard stops working once in the BIOS..

Does anyone know what pins on the AMIKEY-2 go to the chipset that would relate to PS2 functionality? I'd like to check continuity. Also would appreciate any other ideas people have for troubleshooting!

Updates

  • Replaced most of the through hole tantalum capacitors on the board (haven't done any of the SMD ones)
  • Verified 5v is being supplied to the PS2 connector after boot with a mouse and keyboard connected
  • Bypassed main fuse (top left of board) with soldered wire - no effect

Reply 11 of 13, by Doornkaat

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Other than replacing the controller like you plan to do I only have a few crapshots left:
Try flashing the BIOS again. Maybe it's partially corrupted?
If you're currently using the latest beta BIOS use the latest official one or vice versa.
Remove all cache and try again.

Reply 12 of 13, by airs

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Got the mouse working! Desoldering the AMIKEY-2 and replacing with one I got from eBay did the trick 😀

Reply 13 of 13, by Horun

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Great job ! Would not have thought the KB controller was the problem but it was

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

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