Amiga 2000 keyboard schematics

Brannigan · 07 February 2014, 12:03

I've rewired an Amiga 2000 keyboard to replace the keyboard for my Amiga 1000 (approx 1/3 of the keys are working). The modification was successful, no magic smoke and I could type. However, a couple of keys doesn't work, like '2' on the numerical pad and 'd'. Also, the whole qwerty row desn't work, from tab to the brackets on the right side. Since the whole row is off I suspect something else that bad switches.

But before I unscrew the internal case and really have a go with this I'd like to have a look at the schematics so I at least know what I'm doing. All those diodes on the backside and I have no idea where they are connected. I have been unable to find any schematics for an A2000 keyboard so my question is, does anyone here have the schematics or ood understadning of how this keyboard works? Big thanks!

davideo · 07 February 2014, 12:05

I've got a 2000 manual at home that includes the schematics for the MB.

I'm not sure if it includes the keyboard as well but I can have a look later and let you know.

If it does I should be able to scan it in for you.

Loedown · 07 February 2014, 13:32

I can't find one online.

Logic dictates that it's using a grid and the keys are divided into that grid. If you open the keyboard and have a poke around then you'll quickly find the arrangement. I just haven't needed to know before now.

mark_k · 07 February 2014, 14:26

It could be one or more traces on the plastic sheets inside have cracked or degraded due to age. Several keys on my original A2000 keyboard stopped working a few years ago. Though I did open the keyboard up at least once and clean the insides with detergent years before that. Maybe that had something to do with it failing.

Jope · 07 February 2014, 18:31

The A2000 keyboard usually doesn't have a plastic sheet, it has a single sided PCB instead.

Perhaps one of the diodes or jumpers have a bad solder joint or perhaps one of the traces on the copper side has broken.

Don't be tempted to remove the black blobs on the contact side, just clean them off with rubbing alcohol.

davideo · 07 February 2014, 22:12

Although the manual includes schematics for the MB it doesn't have anything for the keyboard.

Brannigan · 07 February 2014, 23:41

I removed the shield and it looks like there is corrosion. I do not get a connection from the solder joint on the first photo and num. 2 key. The second photo is the line going to the enter key (which doesn't work either). Here it seems that the pad has been corroded as well. I haven't managed to find anything regarding the 'd' key. I cleaned the whole PCB with IPA so at least it's clean now.

Brannigan · 08 February 2014, 01:49

Ok, I managed to get '2' to work by adding a 'bypass' wire over the damaged are to the joint. Right side of the joint is ok, even if it looks bad. I'm really not proud of my solder job so I won't post a photo. But it works and you can't argue with success, right? I did check all traces for the 'd' key and nothing! It turned out to be dust on the foot of the key. Some rubbing with IPA and now it's ok.

The real problem is near the enter key. The copper near the pad is ruined. In fact, it's ruined all the way to the pad and so is part of the pad it seems. So a bypass solution seems unlikely.

What are these pads made of? It seems to be resisive so I guess leave them untouched if possible. Is it possible to solder onto them? Is it possible to solder a bypass wire ontop of the pad and it will work? Without knowing the properties of the pad, or what the switch is doing andhow the detection is done I can't continue.

Loedown · 08 February 2014, 02:27

Run a bypass from the left track to the right track using mod wire as the right side looks like it's connected well to the pad. Just make sure the mod wire won't foul with the keyboard plate.

Brannigan · 08 February 2014, 04:54

I did it and all keys work except enter. It seems that the corrosion has damaged the pad. I get a reading of 1.1kOhm from the pad to a nearby solder joint. From good pads to a nearby solder joints I get a reading of around 30-80 Ohm.

I need to change the pad or create a work around. I tried to have some wire on the pad but it doesn't work that well. I guess I need more surface area. And I guess it has to be flat. Btw, from foot to foot under the key the resistance is around 200 Ohm. What about conductive tape? Or is there some kind of conductive paint available?

Loedown · 08 February 2014, 05:35

There is conductive paint. Redo your solder connections on the tracks and scrape more resist off each side first, the right hand one looks to be a bit hit and miss.

http://www.amazon.com/Keypad-Restore.../dp/B0026PRMVM

Something like that perhaps.

Brannigan · 10 February 2014, 08:24

Success! I used some wire on top of the pad and it works ok. I have to press the button fairly firmly all the way down, a bit annoying to be honest. But then I tested other buttons and they behave the same, probaly a 'feature' of these rubber feet so I guess it's all good

07 February 2014, 12:03	#1
Brannigan Registered User Join Date: Jan 2014 Location: Melbourne, Australia Posts: 40	Amiga 2000 keyboard schematics I've rewired an Amiga 2000 keyboard to replace the keyboard for my Amiga 1000 (approx 1/3 of the keys are working). The modification was successful, no magic smoke and I could type. However, a couple of keys doesn't work, like '2' on the numerical pad and 'd'. Also, the whole qwerty row desn't work, from tab to the brackets on the right side. Since the whole row is off I suspect something else that bad switches. But before I unscrew the internal case and really have a go with this I'd like to have a look at the schematics so I at least know what I'm doing. All those diodes on the backside and I have no idea where they are connected. I have been unable to find any schematics for an A2000 keyboard so my question is, does anyone here have the schematics or ood understadning of how this keyboard works? Big thanks!

07 February 2014, 23:41	#7
Brannigan Registered User Join Date: Jan 2014 Location: Melbourne, Australia Posts: 40	I removed the shield and it looks like there is corrosion. I do not get a connection from the solder joint on the first photo and num. 2 key. The second photo is the line going to the enter key (which doesn't work either). Here it seems that the pad has been corroded as well. I haven't managed to find anything regarding the 'd' key. I cleaned the whole PCB with IPA so at least it's clean now. Attached Thumbnails

08 February 2014, 01:49	#8
Brannigan Registered User Join Date: Jan 2014 Location: Melbourne, Australia Posts: 40	Ok, I managed to get '2' to work by adding a 'bypass' wire over the damaged are to the joint. Right side of the joint is ok, even if it looks bad. I'm really not proud of my solder job so I won't post a photo. But it works and you can't argue with success, right? I did check all traces for the 'd' key and nothing! It turned out to be dust on the foot of the key. Some rubbing with IPA and now it's ok. The real problem is near the enter key. The copper near the pad is ruined. In fact, it's ruined all the way to the pad and so is part of the pad it seems. So a bypass solution seems unlikely. What are these pads made of? It seems to be resisive so I guess leave them untouched if possible. Is it possible to solder onto them? Is it possible to solder a bypass wire ontop of the pad and it will work? Without knowing the properties of the pad, or what the switch is doing andhow the detection is done I can't continue. Attached Thumbnails

08 February 2014, 04:54	#10
Brannigan Registered User Join Date: Jan 2014 Location: Melbourne, Australia Posts: 40	I did it and all keys work except enter. It seems that the corrosion has damaged the pad. I get a reading of 1.1kOhm from the pad to a nearby solder joint. From good pads to a nearby solder joints I get a reading of around 30-80 Ohm. I need to change the pad or create a work around. I tried to have some wire on the pad but it doesn't work that well. I guess I need more surface area. And I guess it has to be flat. Btw, from foot to foot under the key the resistance is around 200 Ohm. What about conductive tape? Or is there some kind of conductive paint available? Attached Thumbnails

10 February 2014, 08:24	#12
Brannigan Registered User Join Date: Jan 2014 Location: Melbourne, Australia Posts: 40	Success! I used some wire on top of the pad and it works ok. I have to press the button fairly firmly all the way down, a bit annoying to be honest. But then I tested other buttons and they behave the same, probaly a 'feature' of these rubber feet so I guess it's all good Attached Thumbnails

07 February 2014, 12:05	#2
davideo Amiga Tomcat Join Date: Sep 2007 Location: Boston Lincs Posts: 1,500	I've got a 2000 manual at home that includes the schematics for the MB. I'm not sure if it includes the keyboard as well but I can have a look later and let you know. If it does I should be able to scan it in for you.

07 February 2014, 13:32	#3
Loedown Precious & fragile things Join Date: Feb 2009 Location: Victoria, Australia Posts: 1,946	I can't find one online. Logic dictates that it's using a grid and the keys are divided into that grid. If you open the keyboard and have a poke around then you'll quickly find the arrangement. I just haven't needed to know before now.

07 February 2014, 14:26	#4
mark_k Registered User Join Date: Aug 2004 Location: Posts: 3,337	It could be one or more traces on the plastic sheets inside have cracked or degraded due to age. Several keys on my original A2000 keyboard stopped working a few years ago. Though I did open the keyboard up at least once and clean the insides with detergent years before that. Maybe that had something to do with it failing.

07 February 2014, 18:31	#5
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,861	The A2000 keyboard usually doesn't have a plastic sheet, it has a single sided PCB instead. Perhaps one of the diodes or jumpers have a bad solder joint or perhaps one of the traces on the copper side has broken. Don't be tempted to remove the black blobs on the contact side, just clean them off with rubbing alcohol.

07 February 2014, 22:12	#6
davideo Amiga Tomcat Join Date: Sep 2007 Location: Boston Lincs Posts: 1,500	Although the manual includes schematics for the MB it doesn't have anything for the keyboard.

08 February 2014, 02:27	#9
Loedown Precious & fragile things Join Date: Feb 2009 Location: Victoria, Australia Posts: 1,946	Run a bypass from the left track to the right track using mod wire as the right side looks like it's connected well to the pad. Just make sure the mod wire won't foul with the keyboard plate.

08 February 2014, 05:35	#11
Loedown Precious & fragile things Join Date: Feb 2009 Location: Victoria, Australia Posts: 1,946	There is conductive paint. Redo your solder connections on the tracks and scrape more resist off each side first, the right hand one looks to be a bit hit and miss. http://www.amazon.com/Keypad-Restore.../dp/B0026PRMVM Something like that perhaps.

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