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ZX48K: KILLING keyboard membrane?

Mister BeepMister Beep
edited November 2010 in Hardware
Hi.

My friend - JAD - decided to get back from C64 to ZX Spectrum 48K after some break
(that's the man who coded this program http://www.pouet.net/prod.php?which=52155 ),
and hi discovered his Rubber's keyboard got broken.

He bought the new popular membrane, beeing also sold by Rwap (but he bought it from the producer or something like that).

He's kind of 'electronic/soldering' animal, so it wasn't problem for him to replace the membrane. But it wasn't working and the seller said that "it's good for 100% and they're tested before selling, thet he should keep trying" and so on. The usual.

And while next attemptst the ZX48 has died totally. Now he can see only colorlful rubbish on the scren, when he turn the Spectrum on.

1) What could be broken, in your opinion?
2) Can faulty membrane kill such things like converter/transverter or RAM?

Thanks in advance,
MB
Post edited by Mister Beep on
ZX Spectrum 48K BEEPER Music:
http://mister_beep.republika.pl/

Comments

  • WinstonWinston
    edited November 2010
    1. Likely, lower RAM and/or the internal switch mode power supply (the -12v/-5v supply). Look at the data sheet for the 4116 RAM and test the voltages to the supply pins. If the voltages are OK, it's still possible that you have dead 4116 memory.
    2. Less likely, but possible: bad ULA. See an earlier post in this forum about a keyboard not working due to a ULA fault. This is easy to test if you have another ULA handy because they are socketed. (Just make sure you swap with like types: the 5C ULA is different to the 6C).

    It's unlikely in the extreme that replacing a membrane could accidentally kill something else, except in the case of static discharge. Carpeted room? Dry atmosphere? Static tends to be a bigger problem in the winter in the continent where the air can be very dry especially in a heated building. (Less of a problem in soggy Britain).
  • Mister BeepMister Beep
    edited November 2010
    Thanks a lot Winston, I do appreciate your help. I forwared all of this to JAD. He will make more experiments soon.
    Thanks again!
    MB
    ZX Spectrum 48K BEEPER Music:
    http://mister_beep.republika.pl/
  • rwaprwap
    edited November 2010
    Just as an aside - if he did not purchase the keyboard membrane from me or Sintech, then it is likely that he purchased it from a certain manufacturer in Poland (not the one that produces our membranes).

    I have heard some poor comments about the quality of his membranes, although I have not checked them myself.
    Supporting Sinclairs since 1986 !

    www.rwapsoftware.co.uk
    www.sellmyretro.com
  • -Micky-Micky
    edited November 2010
    rwap wrote: »
    I have heard some poor comments about the quality of his membranes, although I have not checked them myself.
    And who is this seller?


    Micky
  • Mister BeepMister Beep
    edited November 2010
    Sadly I know only a nickname of the man who seels it in PL.
    And it would rather say nothing to you.
    He doesn't reveals the manufacturer however I assumed only one company in PL produces the membranes.
    Anyway. It might be even not be related with the broken Spectrum after all.
    We were only guessing.
    ZX Spectrum 48K BEEPER Music:
    http://mister_beep.republika.pl/
  • -Micky-Micky
    edited November 2010
    I bought 2 ZX 48K membrans in Poland and the works very well.


    Micky
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