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Spectrum+ Question

kev1049kev1049
edited June 2013 in Hardware
Just bought an "as is" Spectrum+ from eBay. It has "upgraded" stamped in red on the underside on the expansion port. Does this mean someone has upgraded their old rubber key model?

Upon plugging it in, not all the keys work. There seems to be a group not working in the lower half of the keyboard - b, n, m etc. plus a couple of others.

Also the " key does a 'P' and the ; does an 'O'. Does this sound like a membrane problem? Has it not been upgraded properly?

Any ideas?
Post edited by kev1049 on

Comments

  • Battle BunnyBattle Bunny
    edited June 2013
    This article Adding the Plus from ZX Computing gives a detailed description of the Spectrum+ upgrade kit, so you can compare it with yours. It certainly had "UPGRADE" stamped on the back. In Stage 4 it mentions that the keyboard might partially work if all the ribbon connections aren't secure; it could also be damage to the membrane or the ribbons or their connections. The only option is to take it apart and have a look.
  • fogfog
    edited June 2013
    the membranes do age / stop working.. but the issue is , the membrane for the + is the same as the 128 , and not as cheap as the 48k rubber key one

    with regard to loading, instead of using the P to do the " on the keyboard for load "" , look on the bottom row and you should see a " key that you can use, hopefully

    QAOPM were the most used keys on my spectrum , and others I guess :)

    you can buy new membranes.. RWAP sells em for a start.
  • kev1049kev1049
    edited June 2013
    Thanks for the advice. I think it needs a new membrane however the fact that when i press the dedicated " key on the bottom row a 'p' is produced suggests a problem with the ribbon?
  • JeffBJeffB
    edited June 2013
    Yeah the " key effectively presses both P and symbol shift at the same time (it's a multi-layered membrane) - the bit that presses "P" works, but not symbol shift - which makes sense when you know that symbol shift shares a line with the other keys you have that don't work.

    There are two ribbon 'tails' that come from the membrane down to the PCB - the one that has 8 lines on it is broken somewhere. If you're lucky, it'll be right at the end that plugs into the PCB - you can trim 5 or 10 mils of the end of the ribbin and still plug it in... If it's higher up, then I'm afraid it's new membrane time.
  • kev1049kev1049
    edited June 2013
    Thanks Jeff. That's really helpful. Ill take a look at the connector. I'd like to avoid buying a new membrane if possible seeing as I only paid a fiver for the computer!
  • JeffBJeffB
    edited June 2013
    Just go careful when opening the machine - as you can probably gather from the fault, the membrane's "ribbon tails" get brittle with age and if you're not careful you can yank them around when opening the case up.
  • PierrePierre
    edited June 2013
    Just some advice for newcomers from my experience with replacing keyboard membranes on the ZX Spectrum. The original membranes are fitted with plastic inserts on the connector sides. They ensure a tight fit in the connector which minimise the chance of bad contact between the connection side and the connectors on the motherboard. They also strengthen the membrane connections when it is inserted and when you remove the membrane from the motherboard. During the long time that the keyboards are inserted into the plugs, the connection points in the plugs are forced open by the insert. When the old membrane is removed, the connection points are wider open than when it was manufactured. When fitting a new membrane, the new membranes do not always make good contact because the connection side of the membrane are thinner on the new membrane as with the old membrane with the inserts. To ensure a tight finish, remove the plastic inserts from the old membrane connector and fit it to the new membrane contacts.

    Original Connection Insert and connectors on motherboard

    Membrane Old.JPG

    Keybord 1.JPG

    Keybord 2.JPG

    New RWAP keyboard membrane with inserts from old membrane

    Membrane new 1.JPG

    Membrane new2.JPG
  • kev1049kev1049
    edited June 2013
    Update: Just opened up the Speccy and trimmed the 8 line ribbon as described by Jeff. It wasn't broken but had bent over a bit. Anyway after reinserting I now have a fully functioning keyboard!

    I now have a 48k rubber key model and the Spectrum+. Hmmm someone's selling a +2 on eBay....
  • pkerseypkersey
    edited June 2013
    kev1049 wrote: »
    Update: Just opened up the Speccy and trimmed the 8 line ribbon as described by Jeff. It wasn't broken but had bent over a bit. Anyway after reinserting I now have a fully functioning keyboard!

    I now have a 48k rubber key model and the Spectrum+. Hmmm someone's selling a +2 on eBay....

    Congratulations!
  • napoleonblownapartenapoleonblownaparte
    edited June 2013
    I have a case with 'Upgraded' on it, stupidly it was the one I used for my Raspberry Pi project but didn't realise 'till it was too late - it really is upgraded now though...
  • JeffBJeffB
    edited June 2013
    kev1049 wrote: »
    Update: Just opened up the Speccy and trimmed the 8 line ribbon as described by Jeff. It wasn't broken but had bent over a bit. Anyway after reinserting I now have a fully functioning keyboard!

    I now have a 48k rubber key model and the Spectrum+. Hmmm someone's selling a +2 on eBay....

    Ace! Glad I could help :)
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