News:

Printed Amstrad Addict magazine announced, check it out here!

Main Menu
avatar_talrek

Keyboard or Mainboard problem

Started by talrek, 15:57, 21 October 14

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

talrek

Hi,
here is my problem, i hope someone will be able to help me.


I have a Qwerty CPC6128 which has "Keyboard" problems, in fact i think it isn't a keyboard problem.
When I hit the DEL key for example, it makes a lot of strange characters on the screen, other keys are OK.
And when i use a joystick i don't have the Arrow characters, but strange characters instead.


I changed the Z80, I change the keyboard to see if it was related.
Every thing else is working great : Disc, Parados, Megaflash when connected.


Any clues ?  :'(




CraigsBar

Can you swap the ay? I had a similar issue once, and a new ay fixed it.
IRC:  #Retro4All on Freenode

Bryce

Dodgy Firmware ROM?

Bryce.

talrek


Quote from: CraigsBar on 16:11, 21 October 14Can you swap the ay? I had a similar issue once, and a new ay fixed it.



Ok, i will try tomorrow with a new AY (if i have one...)

Quote from: Bryce on 16:11, 21 October 14
Dodgy Firmware ROM?

Bryce.



I will try also ;-) , i must have a Parados Eprom somewhere  ::)


Bryce

It's very unlikely to be the AY, no AY failure could cause those effects. Only try a different AY if it's already socketed. It's also more likely to be the Firmware/BASIC ROM, not the AmsDOS (where ParaDOS goes).

Bryce.

talrek

Ok,
i'm going to desolder the Basic ROM first just to try a "good" one !
Thank you again :)

TFM

If it isn't the ROM or the AY, then it could be the PIO8255.


Good luck!

TFM of FutureSoft
Also visit the CPC and Plus users favorite OS: FutureOS - The Revolution on CPC6128 and 6128Plus

talrek

Well in order :
The basic, the AY and then the PIO
Got a lot of work ;-)


Thank you

TFM

Yes, but later you got a socket for all of them! And that's awesome!  8)
TFM of FutureSoft
Also visit the CPC and Plus users favorite OS: FutureOS - The Revolution on CPC6128 and 6128Plus

Bryce

Quote from: TFM on 17:12, 23 October 14
Yes, but later you got a socket for all of them! And that's awesome!  8)

Yes, but it also means that you have destroyed perfectly good hard to get parts if you just blindly swap them all.

Bryce.

TFM

Quote from: Bryce on 18:35, 23 October 14
Yes, but it also means that you have destroyed perfectly good hard to get parts if you just blindly swap them all.

Bryce.


He only swaps the broken parts.[nb]Or the parts having been suggested here.[/nb]
TFM of FutureSoft
Also visit the CPC and Plus users favorite OS: FutureOS - The Revolution on CPC6128 and 6128Plus

Bryce

Quote from: TFM on 19:57, 23 October 14

He only swaps the broken parts.[nb]Or the parts having been suggested here.[/nb]

Not all the parts suggested here are broken. The AY is very unlikely to be broken.

Bryce.

TFM

Well, we will see at the end... we could actually do some bets  ;)


I guess the AY has a bigger chance to be broken than the PIO. Also if the Basic-ROM would be broken, you would rater get random effects or just altered keys, but the way he describes it the problem is located in key scanning, in particular the AY reports a bunch of keys not pressed.


One quid on the AY  ;)
TFM of FutureSoft
Also visit the CPC and Plus users favorite OS: FutureOS - The Revolution on CPC6128 and 6128Plus

Bryce

He says the DEL key produces "lots of characters". Any AY problem can give you wrong or no character, but no AY failure would cause lots of characters to appear. You get two characters if an AY internal pull-up resistor fails, but it still gives the correct character first. Even if they all failed, I don't think it would cause that and it would effect all keys the same.

Bryce.

robcfg

Dirty keyboard membrane or failing membrane contact to the motherboard, maybe?

Bryce

Quote from: robcfg on 14:41, 24 October 14
Dirty keyboard membrane or failing membrane contact to the motherboard, maybe?

That still wouldn't cause multiple strange characters to appear.

Bryce.

ZbyniuR

My friend once repaired 464 and 6128 which had problems with kays with bigger numbers than 70. Sequences of characters on screen in each of them were different, but, after changed AY problem disappeared.
He said that it looks like AY had a gates that PIO uses to operate the keyboard and joystick. But such AY which making problem in CPC still playing well in sound cards for ZX Spectrum.
I guess cause was test connecting something strange to joystick port.
In STARS, TREK is better than WARS.

TFM

Quote from: Bryce on 21:12, 23 October 14
He says the DEL key produces "lots of characters". Any AY problem can give you wrong or no character, but no AY failure would cause lots of characters to appear. You get two characters if an AY internal pull-up resistor fails, but it still gives the correct character first. Even if they all failed, I don't think it would cause that and it would effect all keys the same.

Bryce.



I bet you a beer it's the AY! Because if it fails, it can start delivering random bits so you get lots of characters when pressing one key.  ;)


Quote from: robcfg on 14:41, 24 October 14Dirty keyboard membrane or failing membrane contact to the motherboard, maybe?



He exchanged the keyboard already.  :)
TFM of FutureSoft
Also visit the CPC and Plus users favorite OS: FutureOS - The Revolution on CPC6128 and 6128Plus

talrek

yes i tested the keyboard, so it is not that.I just removed the 40025 today, so i will solder the socket tomorrow and test it  8)  First answer tomorrow  8)   Who will win ?  ;D 

TFM

My best wishes! Hope it will work again soon!
TFM of FutureSoft
Also visit the CPC and Plus users favorite OS: FutureOS - The Revolution on CPC6128 and 6128Plus

Bryce

Hi Talrek,
     just fixing a CPC+ at the moment and it has a similar problem to what you describe. Is this the series of characters you get when you press DEL? If so, changing the AY doesn't solve the problem, nor does changing the ROMs. Unfortunately, this is a plus, so it doesn't have a 8255 PIO, but I'll let you know as soon as I've found the issue...

Bryce.



talrek

 :laugh:  I was just going to reply that i changed the Basic and AY and it doesn't work  :laugh: :laugh:


All this work for "almost" nothing  (in fact i have the luck to have now a CPC with two more sockets  ;D [size=78%])[/size]



Then i saw your message : it is EXACTLY the same characters when i hit the DEL key.


Do you want that i try to change the 8255 PIO (even if i think it isn't the cause...) ??




CraigsBar

Quote from: Bryce on 14:39, 25 October 14
Hi Talrek,
     just fixing a CPC+ at the moment and it has a similar problem to what you describe. Is this the series of characters you get when you press DEL? If so, changing the AY doesn't solve the problem, nor does changing the ROMs. Unfortunately, this is a plus, so it doesn't have a 8255 PIO, but I'll let you know as soon as I've found the issue...

Bryce.
If that was one of the boards I sent you then it looks like the AY swap did not fix it for me 7 years ago and my memory is failing :(


Sorry.
IRC:  #Retro4All on Freenode

Bryce

Quote from: talrek on 17:43, 25 October 14
:laugh:  I was just going to reply that i changed the Basic and AY and it doesn't work  :laugh: :laugh:


All this work for "almost" nothing  (in fact i have the luck to have now a CPC with two more sockets  ;D [size=78%])[/size]



Then i saw your message : it is EXACTLY the same characters when i hit the DEL key.


Do you want that i try to change the 8255 PIO (even if i think it isn't the cause...) ??

Ok, so we have exactly the same issue, good to know. The plus doesn't have a PIO, so that's not going to be the issue. However, I have noticed that this PCB also has problems with the floppy drive, does yours too? Also one other thing that I noticed. Mine has a French keyboard and an English ROM, what about yours?

Hopefully I can check it some more today and maybe find the solution.

Bryce.

arnoldemu

Bit 7 or D7 is stuck. All these keys are on the same bit but over multiple keyboard columns. Is there a short somewhere between keyboard and ay?
My games. My Games
My website with coding examples: Unofficial Amstrad WWW Resource

Powered by SMFPacks Menu Editor Mod