Posted By
Plus4Vampyre
on 2003-10-18
 |  Keyboard failure
Hi,
I bought a C116 at ebay it is working but the keyboard has a failure. The first key line F1 to Del/inst is working also Return,Q and one of the shift keys. Is there somebody how knows what could be wrong with these c116? Is it the keyboard or one of the chips inside? Thanks a lot.
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Posted By
Ulysses777
on 2003-10-18
| Re: Keyboard failure
First thing to check is the ribbon cable connecting the keyboard to the main PCB, either a loose connection or a damaged cable.
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Posted By
Plus4Vampyre
on 2003-10-18
| Re: Keyboard failure
the connection cable looks ok - no optical damage visible
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Posted By
JamesC
on 2003-10-18
| Re: Keyboard failure
I think the C116 and the Plus/4 share the same keyboard ribbon. Do you have a Plus/4 that you could put the keyboard onto the C116 for testing?
The keyboard scan lines are read by TED, so if swapping keyboards doesn't work, replace TED.
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Posted By
Plus4Vampyre
on 2003-10-18
| Re: Keyboard failure
Yes I have two Plus/4's and a C16 so I can test the keyboard with the C116 I bougth
I am not into the c16/c116 / Plus4 hardware, but I can that there is the TED Basic and the TED Kernel - I think you mean the TED kernel - can you tell me the description of the TED ? What is printed on the chip? Thank you very much.
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Posted By
JamesC
on 2003-10-18
| Re: Keyboard failure
TED is the name of the all-purpose graphic and sound chip that the whole series was built around. So when we refer to TED we're talking about the chip in the metal cage on the motherboard, marked 7501 or 8501.
Kernal and BASIC are support (software) chips, ROMs, that in this circumstance are customized to work with TED to produce a working input/output system. Therefore these particular ones might be called TED BASIC and TED Kernal, but here we simply refer to them as BASIC 3.5 and Kernal. If we're talking about another computer like a VIC or a C64 then we're be more specific.
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Posted By
Ulysses777
on 2003-10-19
| Re: Keyboard failure
Correction to JamesC's post: the TED chip is actually labelled 7360 or 8360.
Also, the metal cage is only present on the Plus4, it's not on the C16. On the C16, the TED chip is the largest one, and it's positioned near dead centre of the board.
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Posted By
Plus4Vampyre
on 2003-10-19
| Re: Keyboard failure
the fuse was brigded so maybe that damaged the TED - I am going to replace the TED and try it again - if it wasn't the TED I have a reserve for my plus4's and c16. Thanks a lot
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Posted By
SVS
on 2003-10-22
 | Re: Keyboard failure
---> Plus4Vampyre: Be sure you'll try inserting the suspected-burn TED into a well working Plus4/C16, and not the contrary!
>>"the fuse was brigded"
I don't understand who works in this way 
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Posted By
Noro
on 2003-10-22
| Re: Keyboard failure
I would suggest to check the down side of the rubber keys first.
The C116 keyboard is made of one pressed piece of rubber with some sort of conductive material on the down side of the keys which wears off quite quickly.
I had this problem with my C116 too and I solved it by sticking the aluminium foil from chewing gum packages with the paper side on the down side of the keys.
To reach the rubber keyboard you have to screw the board off the top keyboard case.
-> Ulysses777 the C116 indeed has a metal cage as the Plus/4 in contrast of the C16
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Posted By
Plus4Vampyre
on 2003-10-22
| Re: Keyboard failure
First thanks to all for the usefull hints. Brigding a fuse with a conductor or aluminium foil seams popular "method" yesterday I got a C64 and the fuse was also bridged. I don't work in this was so I replaced the fuse in my c116. The TED chip seems to be ok. Noro is right the problem is the keyboard and the rubber keys. I pressed one rubber key for a long time relasing it and pressing it again and releasing it and pressing it .....- in this way some of the keys are working again. So the problem here is the rubber keyboard
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