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Author Topic: Videopac +G7400 bad keyboard keys  (Read 164 times)
Dr.Wily
Trying to get the cartridge in...
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Posts: 3


« on: May 10, 2017, 11:16:01 PM »

Hello ! My first post here  Cheesy

I have a very anoying problem with my Videopac +G7400. All is in good working order, I found this beast at 5 and I restored it. A memory IC was bad, RGB cable totaly wear by rust and PSU have worn capacitors. I replaced the RAM IC, made a new RGB cable and changed the cap on PSU.

The Videopac turn on and work flawlessly with a bright and stable picture... but I cant start many game beacause of a defect keyboard.

Some keys work and others not. For example when I press "/\" key I have "which game ?" screen but I cant select a level because of no working numbers keys. Only 8 and 9 keys work (it produce sound when I press it). I have the chess module C7010 and I can't start the game. It use 1 or 2 key + 1 to 6 keys.

I check the membrane of the keyboard, and I notice some trace are bad, thre are crumbled and it's impossible to fix because if I unstick the membrane all trace will be damaged. Strangely, there is no real fix for this issue on the web and I am astonished the is no replacement part for this.

Have you some tips ti fix or replace this keyboard ? I have a perfectly working Videopac but unusable because of a bad keyboard... too bad.
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Rene_G7400
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« Reply #1 on: May 11, 2017, 09:31:13 AM »

Are you sure that the keyboard itself is causing the problems and not one of the two keyboard decoding ICs?
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Dr.Wily
Trying to get the cartridge in...
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Posts: 3


« Reply #2 on: May 11, 2017, 10:05:57 AM »

Not sure that it's not decoding ICs. But When I remove keyboard from the case, some traces detach from the keyboard membrane.

EDIT :confirm, this is not the keyboard decoding ICs. I tested by shorting pins on keyboard's connector and it works.

Pins 1 to 18 :

1+8 = key "1"
1+9 = key "2"
1+10 = key "3"
1+11 = key "4"
1+12 = key "5"
1+13 = key "6"
...and so on

15+14 = key "/\"

If someone hardy can make the matrix of the keyboard...  Roll Eyes

I back to my firsts questions :

- Why is there no real fix for this issue on the web ? (maybe I have badly searched)
- Where to find replacement ou fix parts ?

« Last Edit: May 12, 2017, 09:48:07 AM by Dr.Wily » Logged
gertk
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« Reply #3 on: May 12, 2017, 06:51:03 PM »

The flexcable from the keyboard is normally quite long and you can simply cut of a small piece at the end and try to insert it again.
 
Another approach, when the flexcable from the keyboard is broken halfway for example, is to desolder the connector from the PCB, attach some 'normal' flatcable between the connector and the PCB and just shorten the flexcable up to the point where the 'breach' is and insert it into the connector . Not pretty but it does the job.

If just a single conductor is broken you can try and fix it with conductive glue, the silver based glues work best. The cheaper black conductive glue is not very 'sticky' and breaks off easily.
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>>G7000 G7200(P+S) G7400 N60 JET27 VG5000 MINITEL P2000T ZX80 ZX81 ORIC-1 COMX35 Aquarius<<
Dr.Wily
Trying to get the cartridge in...
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Posts: 3


« Reply #4 on: May 12, 2017, 07:53:37 PM »

OK found the issue. Flat cable pin 1 is worn and lost it conductivity.

If just a single conductor is broken you can try and fix it with conductive glue, the silver based glues work best. The cheaper black conductive glue is not very 'sticky' and breaks off easily.

It's that. Did you some glue brand  to advise me?
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gertk
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« Reply #5 on: May 18, 2017, 12:23:25 PM »

Bison Electro works ok but is quite expensive..

Conrad has something called 'Wire Glue' but I have no experience with it.

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>>G7000 G7200(P+S) G7400 N60 JET27 VG5000 MINITEL P2000T ZX80 ZX81 ORIC-1 COMX35 Aquarius<<
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