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Re: Dot crawl and keyboard membrane.

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I'm not sure if the dot crawl was so bad before I replaced the keyboard 
membrane. I'd only really fired it up long enough to find out the keys 
were not working. 

It is probably an issue 2, as it has the shiny circuit board traces 
without solder resist. I also upgraded the ram to 48K by putting chips in 
the sockets. I changed the video out to composite too, so it's probably 
not interference from the monitor. The monitor is a Sony PVM, and they 
are normally quite well behaved.

Replacing some decoupling capacitors sounds like it might help. It does 
look like the interference is quite related to what the computer is 
doing, rather than being the slow steady crawl that I remember from my 
Spectrum when I was young. 

I bought this one second hand, so it might not have been used for years. 
The other spectrum I posted here about is still not working. (I got the 
power supply and inverter going, but I think ULA or lower 16K might be 
broken.) Oh well, I've enjoyed fixing it that far anyway. 

Thanks for the ideas. 

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Thread

Dot crawl and keyboard membrane. philicorda <philicorda@sorrynospam.com> - 2014-01-24 21:26 +0000
  Re: Dot crawl and keyboard membrane. "Brian Gaff" <briang1@blueyonder.co.uk> - 2014-01-25 05:07 +0000
    Re: Dot crawl and keyboard membrane. philicorda <philicorda@sorrynospam.com> - 2014-01-26 22:36 +0000
    Re: Dot crawl and keyboard membrane. Robert Newson <nothanks@bullet3.fsnet.oc.ku> - 2014-02-09 16:39 +0000
      Re: Dot crawl and keyboard membrane. greenaum@gmail.com (greenaum) - 2014-05-21 18:59 +0000
        Re: Dot crawl and keyboard membrane. "Brian Gaff" <brian1gaff@gmail.com> - 2014-05-25 23:58 +0100
          Re: Dot crawl and keyboard membrane. Hanno Foest <hurga-news2@tigress.com> - 2014-06-01 20:35 +0200

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