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Sid1968

Alpha Lock / Joystick Fix

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Hello Mates,

 

i want to do the Alpha Lock / Joystick Fix as described here on my TI-99/4A: Alpha Lock / Joystick Fix

 

The Problem is, that the Backsite of my Keyboard looks so totally different, that i dont know where i have to cut

the conduction path and from where to where i have to wire the diode.

 

I show you the fotos of my keyboards backside. Can you please sign in the foto where to cut and where to use the diode?

 

Kind Regards

Sid1968

 

 

 

IMG_20190911_190930208.jpg

IMG_20190911_190943956.jpg

IMG_20190911_190954829.jpg

IMG_20190911_191005553.jpg

IMG_20190911_191026553.jpg

Edited by Sid1968

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keyboardr_01.jpg

like it says "The keyboard attaches to the TI motherboard with a 15 pin connector. The above picture shows the solder side of that connector. The yellow arrow is pointing at the number "6" connector. This is important because it this connector that the diode needs to be soldered too, and is the pin that one side of the alpha-lock switch connects to."

 

so the number 6 connector on the top connects to the alpha lock at the bottom.. either meter it out (continuity tester?) to determine which trace it is or just put the diode near the plug at the top (I've done this) 

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Thanks for the Foto and your advices. It would be nice if you would add one or two fotos that decribes what you talked about. If you want take my fotos to draw in.

Edited by Sid1968

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16 minutes ago, Sid1968 said:

Thanks for the Foto and your advices. It would be nice if you would add one or two fotos that decribes what you talked about. If you want take my fotos to draw in.

see that wire with the arrow pointed at it?  unsolder that wire there, install diode in the solder hole, trim wire back a bit, strip it, solder stripe side of diode to wire..done   much easier than trying to find the trace on that keyboard

 

keyboardr_04.jpg

 

 

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I remember doing this as a kid and it worked for about 10 minutes.  Once the computer was running for about 10 minutes, the fix would fail.  IIRC, the keyboard would just go to all lowercase.  So, I removed the fix.

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Per Greg’s posts, check that there is continuity between one of the solder points above or below the trace pointed to in the first picture and the solder point pointed to in the second. If that is OK, cut the trace pointed to in the first picture and bridge the cut trace with the diode as shown by the magenta diode graphic.

 

kbd3.png.94922084197040b678e169270b712f67.png

 

kbd2.png.dab325e61c1841c74fe62ab2b447eebd.png

 

,,,lee

 

Edited by Lee Stewart
clarification
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1 hour ago, unhuman said:

I remember doing this as a kid and it worked for about 10 minutes.  Once the computer was running for about 10 minutes, the fix would fail.  IIRC, the keyboard would just go to all lowercase.  So, I removed the fix.

sounds like a poor solder joint

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Thank you folks for the kind advices. The last night where looong... and i read your adviced not until now. I measured and came to this fully functional solution. I cutted the very short conduction path between the two points, where i soldered the diode. 🙂

 

 

IMG_20190912_090441611.jpg

Edited by Sid1968
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18 hours ago, unhuman said:

I remember doing this as a kid and it worked for about 10 minutes.  Once the computer was running for about 10 minutes, the fix would fail.  IIRC, the keyboard would just go to all lowercase.  So, I removed the fix.

With the fix the TI-Keyboard behaves like a normal PC-Keyboard.... Press a Key and its lowercased... use it with SHIFT and you get the uppercase... 😎

Edited by Sid1968

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That's true also without the fix. The fix takes care of the fact that the joysticks don't work in all directions if Alpha lock is down.

I installed the diode almost 35 years ago, or so. It still works.

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