"ghost" keypresses on cpc 6128

[trabitboy]

Hello,
I recently had a terrible urge to ( at last, after 20+ years ) learn z80 ,
and port a very simple game of mine to it.


I got quite far developing on winape,
now before I integrate tricky stuff like "timing",
I thought I would need to pick up a real cpc 6128 to test my work.


Sadly, I could get an hxc to work on the machine I picked up,
but it has "ghost keypresses " in a random way ( sometimes a press every few seconds , sometimes doesn't stop typing, see screenshot )


I was wondering if any of you had encountered this problem,
and is there a fix ?

[Bryce]

Most likely just dirt on the membrane and under the keys. Disassemble the keyboard, wipe the membrane with a soft cloth and warm water on a flat surface. Remove all the gunk from under the keys and it should work fine again.

Bryce.

[trabitboy]

Thank you!
Will try that next weekend. 

[TFM]

Good luck with the keyboard 


And welcome here btw 




I'm looking forward to read / see more about your game.

[Gryzor]

Damn, Bryce, can you stop answering first to every question, even the simple ones others can answer as well?


Welcome, man, and good luck with that membrane and your game! Let us know!

[TFM]

Damn right! And then he tells that he would be too busy to do a 4 TB RAM expansion for the CPC 

[Bryce]

It's your fault Gryzor. since I got Tapatalk I can answer hardware questions in a taxi, waiting at the airport, sitting bored in yet another hotel. All places where I can't do much in the way of 4MB RAM expansions

Bryce.

[trabitboy]

thanks for the friendly welcome ! 
I eventually finish all my project ...
... even if they take many years !

[Gryzor]

@Bryce: you mean you can't draw schematics on your knee, on a napkin or something? Come on!


@trabitboy: best of luck to you mate!

[trabitboy]

Hello!
Beware of a noob question : 

A few weeks back I attempted to open the keyboard ,
but I didn't understand how to unlock the ribbon cable from the motherboard ( see pic )
It look very fragile, and I remember on amigas, there was a small clip to move first before moving the ribbon.
Am I really supposed to just pull it?


Also, I'm still making progress on my noob assembly project,
and I don't know it is is "customary" here to do a progress topic
( a lot of these on cpc rulez for instance )
which section of the topic should it be in ?


Have a nice day ! 

[00WReX]

Yes, for the CPC 464 & 6128 simply slide / pull each ribbon out...there is no clip / lock.
For the CPC 664 there is a clip / lock type arrangement.

Cheers,
Shane

[wilco2009]

Additionally to clean the membrane, could be necessary to bend the membrane a bit, repeatedly to unstick the membrane contacts.

Sometimes some of the membrane contacts get stuck.

[Gryzor]

Just make sure you're extra gentle with it and you'll be fine.


And yes, you're in the right place, please post away!

[trabitboy]

Hello,
I finally got around my fear of breaking the ribbon cables and took apart for the keyboard
to give it a good cleaning .
I noticed that :
- the amount of dirt was unbelievable.
- the double membrane seemed a bit sticky  ( so I tried to bend it gently a couple of times.

Upon re-assembly however,
the problem is still there .
Also only some keys seem affected ( the numer row  " # è (  and the left arrow key  ).

It seems attaching my home-made joystick also alters the random keypresses,
so I'm quite inclined to think it is more than the membrane .

Isn't the same chip driving the keyboard and the joystick port since they are both in the keyboard matrix ? ( noob alert  )

It's truly a shame, I couldn't refrain from using this machine since I got it from ebay one year ago ( gets used several times a week ),
but I still couldn't fix it .

[Bryce]

I've just fixed a 6128 with exactly the same problem. IC101 (74LS145) had failed and was causing this.

Bryce.

[trabitboy]

I'll check if it is socketed .


Do you know where I can get one ?
Also, would you be interested in doing the repair work ? ( PM ? )


Thanks for the answer already

[CraigsBar]

I'll check if it is socketed .


Do you know where I can get one ?
Also, would you be interested in doing the repair work ? ( PM ? )


Thanks for the answer already

tee hee hee. There is a waiting list for bryces time. :-)

Get in the queue ;-)

[Bryce]

It won't be socketed. As far as repairing, no problem, send it over it's a 5 Minute Job. You seem to be relatively local to me too.

@Craig: Your request is a little more complicated (Time consuming), which is why I needed to delay it. But you can send it over any time you like and I'll start it as soon as I can.

Bryce.

[trabitboy]

Thank you very much,
PM it is then 

[CraigsBar]

It won't be socketed. As far as repairing, no problem, send it over it's a 5 Minute Job. You seem to be relatively local to me too.

@Craig: Your request is a little more complicated (Time consuming), which is why I needed to delay it. But you can send it over any time you like and I'll start it as soon as I can.

Bryce.

Hehe I know, I was using the chance for some humour to mention that you are a very busy man. Like I said before I am in no real hurry. I have 2 working 6128 pluses at the moment and a x-mem to play with lol.
Craig.

[EgoTrip]

Hehe I know, I was using the chance for some humour to mention that you are a very busy man. Like I said before I am in no real hurry. I have 2 working 6128 pluses at the moment and a x-mem to play with lol.
Craig.

That's greeedy. You should let me have one of them.

[CraigsBar]

That's greeedy. You should let me have one of them.

my spare one (that is currently hosting the x-mem until Bryce has time to upgrade my 464plus) you would not want. It looks like it's spent an age with a 30 a day smoker it's so yellowed. Oddly the cm14 that came with it is still mostly white.

Craig

[trabitboy]

Hello,
my machine is back in full working order,
thanks to a repair from Bryce.


I wanted to thank him publicly for his patience and skill 


Good day to all!

[Bryce]

Hello,
my machine is back in full working order,
thanks to a repair from Bryce.


I wanted to thank him publicly for his patience and skill 


Good day to all!

Hi trabitboy,
      no problem. Glad I could bring yet another CPC back to life Many happy hours with it.

Bryce.