68kMLA Classic Interface

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512k keyboard not working - where to start troubleshooting?
Posted by: JC8080 on 2020-04-17 20:40:56
I recently picked up a 512k complete with the keyboard and mouse.  It appears to be the original keyboard, the type without the 10-key.  A guy was nice enough to send me a boot disk so I was able to get it up and running, and after I booted it up I found the keyboard does not work at all.  None of the keys work, jiggling the cable at either end has no effect.  The keyboard cable looks like the original cable and appears to be in good condition, it doesn't appear to be a phone cord that maybe someone tossed in the box not knowing better, but I can't say for sure.  The computer and keyboard don't appear to have lived a rough life.  The keyboard had a bit of sticky gunk on a couple keys when I got it, but there was no obvious sign that anything had been spilled on it.

Are these keyboards known to fail?  Any thoughts on where to start troubleshooting?  This is the first classic Mac I've owned in many years so I really have no background on them.  Unfortunately I don't have access to a known-good keyboard or known-good machine to swap with.

Thanks for any help
Posted by: bibilit on 2020-04-17 23:43:32
If none of the keys are working, probably a bad solder joint in the keyboard side. 

Open the keyboard casing and have a look inside. 

You should see the connector. 
Posted by: JC8080 on 2020-04-18 12:10:43
If none of the keys are working, probably a bad solder joint in the keyboard side. 

Open the keyboard casing and have a look inside. 

You should see the connector. 
Thanks for the suggestion.  I opened it up and everything looked ok.  I checked the continuity between each of the pins inside the connector to the corresponding point on the board (circled in red in the image), and everything looked good.  Granted I'm far from an expert, but my multimeter went to zero, which seems to indicate no breaks.

Thanks

Keyboard_Inside.jpg
Posted by: Dog Cow on 2020-04-18 13:34:50
This may be a long-shot, but I'll post it here because it happened to me. If the keyboard mapping software on your startup disk is corrupted, the keyboard won't work. There are two INIT resources in the system file, one for the main keyboard, the other for the numeric keypad. If these INITs don't load right, either your keyboard or keypad won't work.
Posted by: JC8080 on 2020-04-18 13:47:36
This may be a long-shot, but I'll post it here because it happened to me. If the keyboard mapping software on your startup disk is corrupted, the keyboard won't work. There are two INIT resources in the system file, one for the main keyboard, the other for the numeric keypad. If these INITs don't load right, either your keyboard or keypad won't work.
It crossed my mind it could be a software issue, but I don't know much about how these systems work, so I wasn't sure if that was a possibility., it seems odd a keyboard would fail completely.  Unfortunately I only have the one boot disk at the moment, so troubleshooting the software further might have to wait until I get a FloppyEmu.  If anyone is in the Seattle area I'd happily buy a 6-pack in exchange for another copy of the OS or a chance to try a different keyboard.
Posted by: Dog Cow on 2020-04-18 13:53:20
Yeah, there's not a whole lot to go on at this point. My next thought is the keyboard cable, but you say it appears to be a genuine Apple cable.
Posted by: JC8080 on 2020-04-18 14:04:25
Yeah, there's not a whole lot to go on at this point. My next thought is the keyboard cable, but you say it appears to be a genuine Apple cable.
Yeah it looks identical to the photos online, and given the condition and completeness of the machine I suspect it probably is.  Unfortunately the probes of my multimeter aren't pointy enough to get in and reach the contacts to check for continuity.
Posted by: bibilit on 2020-04-18 23:43:32
You can use paper clips on each end of your probes to get a better access. 
Posted by: bibilit on 2020-04-19 08:31:27
Also a phone cable can be modified to suit a Macintosh. 

And the standard phone cable won’t work the Macintosh, it will not harm it. 
Posted by: JC8080 on 2020-04-19 09:33:31
You can use paper clips on each end of your probes to get a better access. 
Thanks, I'll have to look into a multimeter that's more versatile, mine is a cheap harbor freight one that doesn't have clips or anything to hold paperclips, just the two leads it came with.
Posted by: bibilit on 2020-04-19 09:44:34
You just can twist the paper clip around each probe. 
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