Re: Dead keyboard!

[Tristan Mumford <xtristan.xmumford@xgmail.xcom>]

Michael J. Mahon wrote:

> Tristan Mumford wrote:
>> Tristan Mumford wrote:
>> 
>> 
>>>Hello,
>>>
>>>As you may have seen I just succeeded in resurrecting my clone.
>>>It has one remaining issue. The keyboard doesn't work.
>>>Well, to be more precise the LED button (control?) + Reset button combo
>>>still works fine, and the LED on aforementioned button stays lit merrily,
>>>but nothing else works.
>>>What's wrong with it?
>>>
>>>By the by, The Apple][ boot text was replaced by "APCOM".
>>>
>>>Tristan.
>>>
>>>
>> 
>> I was just going to pull out the keyboard to find out what's happening.
>> 
>> This isn't normal, right? Please tell me it's not!
>> 
>>
http://members.dodo.com.au/~izabellion1/tristan/fullsize/clone_keyboard.jpg
>> 
>> It's a big picture, so be warned.
> 
> Amazing!  I presume that's stick-on copper foil?

Possibly. But it seems a more like thin copper sheet with glue underneath to
me. I kind of had a bit of a look at it, stared in disbelief for a while,
took the photo and put it away. From what I could see on the edge of a
couple of chips there was some very noticeable sanding of the ICs to rough
them up enough for adhesion.

> 
> Apparently someone was *very* worried about ESD--and in the process
> created a real "ESD antenna" if the ground lug isn't connected.  ;-)

Because I had never looked under the keyboard I always made sure that ground
lead was connected. Although I did question it being anchored by solder to
a user-made hole in the power supply case.

> 
> Frankly, I'd be very surprised if this did anything to improve the
> resistance of the keyboard to ESD anyway.  Providing a lower impedance
> path to ground for discharges coupled to the *pins* of the chips won't
> help.  ;-)
> 
> It *does* make me wonder about the environment in which it was used...

You and me both. I know where I got it from at least. There was a man who
sold all sorts of computer gear and miscellany out of his back shed. It was
a part of an appeasement load of things he gave to me after I bought a
notebook off him that catastrophically exploded. There was a lot of other
weird unidentified gear in that lot too.

Anyway, looks like I have a real problem with the keyboard then. Perhaps. I
still haven't stepped through diagnosis. The 'ESD mod' kind of stopped me
dead.

Tristan.


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