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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: odious on August 25, 2007, 06:50:43 PM
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Hi,
Where to get a replacement or how to repair them?
I'm using liquid silver to restore some broken traces but it's not working.
I once saw someone repairing a membrane using a mixture of graphite (powder scratched from a pencil) and glue but i have tried this before without any results.
Is there any adapter for a pc keyboard that is easy to build and doesn't need software on the amiga?
Any help is appreciated.
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Liquid silver ("Leitsilber") works quite well, but you have to keep it mixed or you'll have too few silver particles on the traces (had to learn that the hard way). Also use plenty of liquid silver and paint the trace as thin as possible with a very thin brush or a toothpick.
I've repaired a few MS Natural Keyboards (damaged by Coke spills) that way (they don't make the Elite any more) and they all still work after quite a few years.
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Funny enough i used a toothpick too. I've repaired a couple of keys but i found out that there are a lot more of them. The traces over the square holes at the plate beneath the membrane are oxidyzed and break easily.
There are also traces broken beneath "bridges" (where traces cross over others) that i cant access. Unfortunatelly i will have to go in another direction.
I wish they had made the kb with a pcb. Quite chronical as i have seen some with non working keys. :(
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U can uz this very simple hack (http://aminet.net/docs/hard/ATkeyboard.lha).
The things u must have are:
- A PIC programmer board (it's bloody simple to make one, btw, and very cheap to buy one);
- A peecee OR Amiga program to save the .hex to the mini-risc cpu (16c84 or 16F84) via serial port;
- The parts listed in the archive. :roll:
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Great. I'll definitely build this. I have one doubt though: What kind of ic is the 7407 ?
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7407 - hex buffers with open collector
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7407, or 74LS07 (LS means low schottky), or 5407, or 54LS07 will do the trick.
They are TTL chips.
Prefer the ls version. IF you are a very lucky guy, you can even find the military version (5407 or 54LS07). Mil-spec jokes, here I come... :-)
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I got an LS. What is so special about those military version chips? Are they less prone to faults?
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odious wrote:
I got an LS. What is so special about those military version chips? Are they less prone to faults?
MIL-spec :-D versions are more tolerant to voltage variations (don't count on it) and heat range (no doubt about this).
They are made in ceramic dies, oposed to plastic dies in regular versions.
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Ok, I have built the board but i could only get 16F84A instead of the obsolete 16c84.
I asked a friend to program the pic and when trying to program it, he got an error. So he changed something to accept the 16f84A instead of the 16c84. He warned me it might not work and so it didn't.
I double checked all the connections and no key works at all, only the num lock led lits on/off when the num lock key is pressed.
I looked at the pinouts of the pics and they are the same but my knowledge on this stops there.
Any help would be appreciated.
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Don't be shy :)
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Buy a serial OR USB pic programmer from anywhere.
A tip: look for it on Ebay, those programmers are common as mud.
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Try building 'IBMKey25' instead - this definitely works. See - Keyboard Adapter (http://www.amiga.org/gallery/index.php?n=1551=38)
For programming the PIC16F84 I built a programmer based on the 'COM84' design - the simplest. Only suitable for old AT style motherboards as newer ATX (or laptops) can't deliver enough juice to the serial port. See - COM84 (http://www.amiga.org/gallery/index.php?n=1408=38)
PM me if you need any help or more info.
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The problem is not having not access to a programmer.
The real problem is that the .hex on those designs are for 16C84 and will not work directly on 16F84 nor 16F84A.
The code has to be assembled to work on 16F84's and i don't know how to do it.
Cheers.