Author Topic: 464Plus membrane  (Read 655 times)

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Offline Beaps

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464Plus membrane
« on: 23:40, 14 November 18 »
Hi All


I checked continuity on my 464plus membrane and it's not good :-(


Are they easy to fix or should I just replace, if so where can I get one as I ant see em on eBay


Ta
B

Offline Bryce

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Re: 464Plus membrane
« Reply #1 on: 10:02, 15 November 18 »
Hi Beaps,
           the plus membranes are relatively robust, are you sure it's damaged? It can be very difficult to measure the continuity on membranes as they tend to oxidise all over. Are certain keys not working or what issue are you having?

I don't know is anyone has created replacements. If it really is broken, I have a replacement keyboard I could send you. It's a French AWERTY version, but the membrane is good and could be swapped over (they all use the same membrane).

Bryce.

Offline Beaps

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Re: 464Plus membrane
« Reply #2 on: 10:23, 15 November 18 »
Hello again buddy,


I get double key inputs, and its always around the letter B, if I press V I get V&B, press C I get C&B. Also if I press DEL I get nothing.


 

Offline Bryce

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Re: 464Plus membrane
« Reply #3 on: 10:59, 15 November 18 »
The DEL problem could be a damaged track, but double keys are a dirt issue.

Bryce.
 

Offline mr_lou

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Re: 464Plus membrane
« Reply #4 on: 11:04, 15 November 18 »
I had issues with my CPC plus a while back too. Certain keys suddenly didn't work.
Then I bought a new membrane and replaced the old one. Everything worked again then.
But recently I've noticed that the same keys that were dead with the old membrane has started giving trouble again. Sometimes they don't work again. So I guess the problem was probably something else.

Offline Beaps

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Re: 464Plus membrane
« Reply #5 on: 11:28, 15 November 18 »
I've cleaned the membrane and it looks like new, so doubt it's a dust issue. Someone said it's a AY38912A issue which I did think was weird as I thought that took care of the sound. I did order one of those and replace it, but it's the same issue. Not sure what else to try only a different membrane.

Offline Bryce

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Re: 464Plus membrane
« Reply #6 on: 11:34, 15 November 18 »
The AY has an 8-bit GPIO port which the CPC uses to read the Keyboard. The other half of the circuit (the keyboard scanning) is done by the ASIC.

Bryce.

Offline Beaps

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Re: 464Plus membrane
« Reply #7 on: 11:46, 15 November 18 »
Ah ok that's most probally why someone said that would be the issue, but it's the same still grrrrrrr

Offline Dr Tiger Ninestein

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Re: 464Plus membrane
« Reply #8 on: 12:18, 15 November 18 »
I had this issue with a 464 plus that i bought. I cleaned the membrane and it still didnt work so i had to buy a replacement membrane.


I got my replacement from trade in post, that was a couple of years ago now but they might still have some in stock.





Offline Bryce

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Re: 464Plus membrane
« Reply #9 on: 12:28, 15 November 18 »
Ah ok that's most probally why someone said that would be the issue, but it's the same still grrrrrrr
When the AY fails, the syptoms are usually random characters appearing at startup or a whole row of keys not working. However, from memory, I think the DEL key is on a row of its own.

Bryce.

Offline Beaps

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Re: 464Plus membrane
« Reply #10 on: 13:00, 16 November 18 »
Any chance I can get that membrane from you mate, I think that will solve my issue.

Offline Bryce

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Re: 464Plus membrane
« Reply #11 on: 13:12, 16 November 18 »
Yeah. I'll get it out at the weekend and check that it still works fully and get back to you.

Bryce.

Offline Beaps

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Re: 464Plus membrane
« Reply #12 on: 14:26, 16 November 18 »
Top man, thanks dude

Offline remax

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Re: 464Plus membrane
« Reply #13 on: 16:46, 17 November 18 »
It's a French AWERTY version





All the time, it was... We finally really did it.
You Maniacs! You blew it up! Ah, damn you! God damn you all to hell!
AWERTY... What kind of bastard have you dooooone !


[Planet of the AZERTYs]

Offline chinnyhill10

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Re: 464Plus membrane
« Reply #14 on: 21:35, 17 November 18 »
I've cleaned the membrane and it looks like new, so doubt it's a dust issue.


I pulled a membrane from a 48k Spectrum last week. Looked as good as the day it was made but it was totally screwed. Visual indicators are of very little use when trying to diagnose faults with membranes.
--
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chinnyhill10 - YouTube

Offline Bryce

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Re: 464Plus membrane
« Reply #15 on: 09:35, 19 November 18 »
Top man, thanks dude

Unfortunately, after tearing the place apart, I can't find the Keyboard anywhere. I suspect I must have given it away at some stage. The box that I thought contained it, now holds an Amstrad EuroPC keyboard, not a plus keyboard :(

Sorry beaps, you're going to have to look further.

Bryce.

Offline Beaps

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Re: 464Plus membrane
« Reply #16 on: 09:49, 19 November 18 »
No worries mate, thanks for looking I really appreciate it