Powerbook 3400c : keyboard issue

[CedsRepairs]

Hey,

Just got a Powerbook 3400c/200

It runs fine, screen fine, expect that... The keyboard does not work,

Or even weirder : only 4 "control" keys work (according to the keyboard app) : shift; shoft lock , alt and Apple. (both lower left corner)

I tried repluuing the flat cable, didn't work.

I'd like to be sure this is not a software issue ( pram is also dead, as the laptop boots as soon as it's plugged in)

Is there a wxay for me to boot the thing" before macos" (in kind of a bios ?)
Is there anything else than a hardware problem that could lead to this ?

 

[GiGaBiTe]

There is a firmware console available on some old world PowerPC Macintosh machines, but it's not going to help you with a keyboard problem. The average user is really not supposed to be messing around in the firmware, it's really only intended for hardware and driver development and low level debugging. Not that you could get there anyway, you need to press a specific key combination (Command-Option-O-F) to access it at boot, and since your keyboard is dead, you have a chicken and egg problem. The PB 3400c does have an ADB port so you can attach an external keyboard, but I'm guessing you don't have one, and they're not exactly cheap.

If the PRAM battery is dead, I'd recommend replacing it because some Macintosh machines either won't work at all, or have erratic behavior with a dead PRAM battery.

 

[Timo W.]

A non-working keyboard is not a software issue.

The keyboard on these units is completely dumb, it's just the foils with no electronics whatsoever. So there are two possibilities: either the contacts are bad or the flex cable is damaged, so the keypresses never reach the system; or the chip that handles the keyboard is bad. The later is easy to test by attaching an ADB keyboard.

 

[CedsRepairs]

Just a follow up on this,

This keyboard behaviour is clearly a problem of leaked battery,
It seems to PRAM battery (varta 3 cells) leaked just a tiny but (more like emitted gases that attacked the tracks) you can barely see it with a microscope,
It seems it leaks right on top of "something" related to the keyboard (the board is extremely densely populated)

The PRAM battery actually sits on top of the keyboard connectors.
But don't expect" "visible" leaks, really. But it's there.

Good news ; coming from "no keys working at all expect 4", now I got "all my keys working except 4" after completely disassembling the unit (which is very difficult), clean it with vingar, let it soak in vinegar, clean it with IPH99 and put it back together.

I'll try disassembling it again, and clean it this time with vinegar (for salts) and them with baking soda (for corrosion) and probably let it soak an hour or so.

This is not for the faint hearted, this disassembly is probably the most complex I've ever seen...

I'm sure this is not a keyboard problem (in my case) as I've bought a new replacement keyboard ( azerty->qwerty) and it displayed the same problem. nd now, only has 4 keys no working, like the original. So both keyboards are OK and affected by" something" going wrong on the logic board, which I 90% fixed .

hope this helps someone.