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Amptron 386DX-40 motherboard

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k2x4b524[

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That is not recognizing ANY keyboard i feed it, ANY, XT AT or Autoswitching, it refuses to see any keyboards. I have replaced the keyboard rom aswell, i'm not sure what is going on here. Anyone else have this type of symptom?
 
Is the battery leaking? How do the traces look around the keyboard connector?
 
Keyboard ROM? Isn't that usually a pre-programmed 8042-family MCU?

Stupid question:

You don't accidentally have the keyboard lock on the motherboard jumpered so it inhibits the keyboard, do you?
 
It has one, it's yellow, and intact, i also just noticed this problem crop up on a couple of my 486 boards too. This is a really puzzling thing, could the keyboards i'm trying to use just too old? I fed it a generic dell quietkey, an IBM autoswitching, a Tandy autoswitching and a digital at-keyboard..
 
k2x4b524[ said:
, i also just noticed this problem crop up on a couple of my 486 boards too.
Click to expand...
So this is not the key lock issue raised by Chuck?

A lot of these motherboards have a pair of pins to which the front panel 'keylock' switch is connected.
And in a lot of those, the switch shorts the pins allowing the keyboard to work.
When the motherboard is removed from its case (and switch removed), one has to short the pins with a jumper to allow the keyboard to work.
 
The thing is, I've owned lots of motherboards, including Amptron (P1s mostly) and I can't ever recall one where the keyboard didn't work and everything else did.

A keyboard controller is a pretty dumb device (very dumb on the 5150/5160) and it's pretty hard wreck it, although I've always wondered what would happen if you plugged a MIDI device into it.

Some Amptron boards have a miniature 6-pin DIN for a mouse and a standard 5-pin DIN for keyboard. You can't plug a PS/2 keyboard into those without an adapter (mini-DIN-to-DIN). A keyboard plugged into the mouse connector will definitely not work.

Dunno if this helps, but take it FWIW.
 
In my experience, it's always been battery leakage (I've never misjumpered a board in my life <T uncrosses fingers>), which sometimes shorts and takes out the fuse as well. You may not be able to see it, but it's there (under a chip socket, etc.).

--T
 
so wait, the keylock leads have to be shorted?! Went and did it, and it said the keyboard is locked, unlock it. So its either i got a run of bad board all of a sudden, or something is wrong with ALL my keyboards. What else could cause this?
 
Last edited:
k2x4b524[ said:
so wait, the keylock leads have to be shorted?!
Click to expand...
Depends on the motherboard. For some, the behaviour is opposite - short to disable. That is why I used, "And in a lot of those".

k2x4b524[ said:
Went and did it, and it said the keyboard is locked, unlock it.
Click to expand...
So the keylock issue is ruled out. Well, for the subject motherboard anyway. Some of the other motherboards may be of the type that require their keylock pins to be shorted.

At least your BIOS/POST indicated that the keyboard was locked. Some give no indication at all.
 
k2x4b524[ said:
What else could cause this?
Click to expand...

Well hidden battery damage (see above). That battery goo is insidious. Sometimes it'll breach the soldermask 'barrier' and creep along a trace or traces until it finds a spot that it can burn thru the trace and *poof*...invisible damage. This can be confirmed, but only recommended as a postmortem procedure (IOW, don't try this if you're still trying to save the board). Use an exacto knife or similar to carefully scrape away the coating till you find the trace(s) that easily pull away (fall off, literally) from the board, and underneath you'll see the burned and blackened looking damage.

--T
 
i'm hoping to save the board, it's my best 386 board, 256kb cache, 32mb ram, 40mhz 386 coupled to a 33mhz green-math co proc that handles 40mhz like cake, this sucker can keep up with a 486-66, passing it in some cases. I don't know why, but it's just a very well built board. *update* i got my bioteq 486-33 to come to life with my model m, as well as 3 of my k6-2s and my pentium pro, so i'm almost sure it's the 386 board, if i can save it, i very much would love that, if not, anyone here got an Amptron 5500DX?
 
Applying Holmesian methodology, all other things being eliminated (if this is actually so), that which remains must be the answer, no matter how impossible.
So, I am calling it the keyboard connector on the mobo check the female pin inputs and the solder connections underneath.

I did like Chuck's answer though, thought for sure that would be it.

I'm a big fan of the 386/40DX myself, so...

Good Luck!
 
Exact same thing! I had this problem with a 486 upgrade (386 board) and I used a dell quietkey also, but I tried many keyboards. Can you post pictures? Even if the battery just starts leAking the etching near the keyboard connector is ruined first. Very importantly, are the keyboard lights flashing then you turn on the computer? If they Are then you only need to check 2 traces on the board near the connector
http://pinouts.ru/Inputs/KeyboardPC5_pinout.shtml
 
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