unwilling keyboard on toastrack 128

For experts to discuss very technical stuff and newbies to ask why the Spectrum they bought off ebay doesn't work.
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jojo
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unwilling keyboard on toastrack 128

Post by jojo »

Hi forum ,

looking through the schematics of my unwilling toastrack 128 , i would assume
for a non working keyboard the first would be ula .............

correct me if i am searching the wrong direction.

unit completes the first tests of the "smart-card" without error , but there is no response from the keyboard at all .

tried new and old membrane to no avail


any suggestions welcome
- Zx81-16k exp.- Spectrum 48 - Spectrum 128- Interface 1& 2 - DIVide - Zx flashcard- Zx printer - Ram turbo-Velleman interface system - Currah microspeech - Ql - 512k exp.- Ql printer - Cst floppy interf.- Double 3.5 fd- Minerva - Qimi-and much more .
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1024MAK
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Re: unwilling keyboard on toastrack 128

Post by 1024MAK »

Have you checked tested the diodes between the Z80 address lines and the 8 way keyboard connector, the pull up resistors between the 5 way keyboard connector and the ULA and the connectors themselves (no ribbon remains in them, solder connections).

Have you tried using a length of thin solid core wire to simulate the keyboard, by touching one end in one keyboard connector (any contact) and the other keyboard connector (again any contact).

Do you have a joystick interface that uses the Sinclair protocol (Interface 1, or similar)? Does the machine respond to joystick inputs?

Mark
:!: Standby alert :!:
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :dance
Looking forward to summer later in the year.
jojo
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Re: unwilling keyboard on toastrack 128

Post by jojo »

smart card with joystick , and wire to touch all kb pins reveals its alive !!

but with both old membrane and new NO action at all....................
- Zx81-16k exp.- Spectrum 48 - Spectrum 128- Interface 1& 2 - DIVide - Zx flashcard- Zx printer - Ram turbo-Velleman interface system - Currah microspeech - Ql - 512k exp.- Ql printer - Cst floppy interf.- Double 3.5 fd- Minerva - Qimi-and much more .
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1024MAK
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Re: unwilling keyboard on toastrack 128

Post by 1024MAK »

Are the metal contacts in the keyboard connectors no longer springy enough to make good contact with the membrane. This is normally a problem with machines that have been rehoused in a third party replacement case with replacement keyboard.

The other possible problem is where the membrane tails (ribbons) are clamped in the keyboard assembly. If the clamps are either not tight enough, the metal layers don’t make good contact. But if the screws are tightened too much, either the thread strips the plastic screw hole or the clamp distorts or breaks.

Do you have a rubber key keyboard to test with (or just a rubber key membrane)?

Mark
:!: Standby alert :!:
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :dance
Looking forward to summer later in the year.
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1024MAK
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Re: unwilling keyboard on toastrack 128

Post by 1024MAK »

Also have a read of this web page.

Mark
:!: Standby alert :!:
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :dance
Looking forward to summer later in the year.
jojo
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Joined: Sun Jun 14, 2020 4:04 pm

Re: unwilling keyboard on toastrack 128

Post by jojo »

SOLVED !!

apparently storing the new membrane for a long time in the attick did cause some contact problems ,

a very gentle clean with alcohol solved the problem .

another lesson learnt .....


jojo
- Zx81-16k exp.- Spectrum 48 - Spectrum 128- Interface 1& 2 - DIVide - Zx flashcard- Zx printer - Ram turbo-Velleman interface system - Currah microspeech - Ql - 512k exp.- Ql printer - Cst floppy interf.- Double 3.5 fd- Minerva - Qimi-and much more .
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ianace
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Re: unwilling keyboard on toastrack 128

Post by ianace »

Not being daft, but is there any of the original membrane ribbon stuck in the Connecter housing just out of sight?

Happened to me once
jojo
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Re: unwilling keyboard on toastrack 128

Post by jojo »

@ ianace ,

happened to me on an old rubberkey version , so started with that check .

but in this case the membrane was stored for some hot/wet periods , and a little cleaning of the contacts ( the extra ones underneath ) solved the problem .
- Zx81-16k exp.- Spectrum 48 - Spectrum 128- Interface 1& 2 - DIVide - Zx flashcard- Zx printer - Ram turbo-Velleman interface system - Currah microspeech - Ql - 512k exp.- Ql printer - Cst floppy interf.- Double 3.5 fd- Minerva - Qimi-and much more .
User avatar
1024MAK
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Joined: Wed Nov 15, 2017 2:52 pm
Location: Sunny Somerset in the U.K. in Europe

Re: unwilling keyboard on toastrack 128

Post by 1024MAK »

Well, that’s an unusual problem, definitely not heard of that with membranes before...

Mark
:!: Standby alert :!:
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :dance
Looking forward to summer later in the year.
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