FS Very early serial ZX81

edited December 2013 in Sales
Sorry in advance if I have put this in the wrong section, please move if wrong!

ZX81
Post edited by Macc on

Comments

  • edited December 2013
    A Zeddy with a serial number :o.

    All my Zeddies lack any form of serial number, and I have issue 1 and issue 3 boards, and one of my issue one boards has a ULA with a date code of 8111, so week 11 of 1981.

    Does anyone know when Sinclair started using serial numbers on ZX81's?

    Mark
  • edited December 2013
    I haven't opened this one up to see what the date code is (I always seem to tear the membranes, no matter how carefully I do it!)
    Ive had quite a few without serials too, did they count do you think?
  • edited December 2013
    You can remove the bottom half of the case without affecting the membrane, as the PCB is screwed to the top half of the case.

    However, some of the case screws are under the rubber feet, which after 30+ years sometimes don't stick back afterwards :(

    With the case bottom removed you can see which issue PCB it is (one or three, there was no issue two as far as anyone can tell) but it is very unlikely that you will be able to see the ULA date code (or indeed any of the other chip date codes) as the chips are mounted on the side of the PCB that is covered by the case top.

    Mark
  • edited December 2013
    There are a small number of 81s with serial numbers on my list:-
    ZX81
    
    001-012464	050311 ?155 (sold with 16K RAM & ZX Printer)
    001-013155	180808 ?16.01
    003-004322	080908 ?20.05
    003-001863	300309 ?16 (1xZX81,1xrubber key,1x48+,1x+2)
    081-016852	281110 ?17.55
    081-020376	060410 ?30
    

    I think serial numbers were only added in later production runs though.
  • edited December 2013
    I have a few here and bit the bullet and opened them up, so far one with a serial 001-09(something) was an issue 1, then an issue 3 no serial followed by an issue 1 no serial.

    Could it be that the ones without a serial are the kits? The ones with, factory produced for retail?

    Btw, that ZX81 I had for sale is now sold
  • edited December 2013
    Hard to tell. For what it's worth, my Issue 1 ZX81 (ULA datecode 8130) with no serial on the case looks to be factory soldered.

    B
    The Spectrum Resuscitation Thread - bringing dead Spectrums back to life
    zx-diagnostics - Fixing ZX Spectrums in the 21st Century (wiki)
    Sinclair FAQ Wiki
  • edited December 2013
    Macc wrote: »
    Could it be that the ones without a serial are the kits? The ones with, factory produced for retail?
    Looking at the soldering on some of mine, no, they look like they were properly soldered. It could be that there was more than one factory, and one factory added serial numbers while the other factory did not.
    Or the ones with serial numbers were originally going to be exported maybe?

    Mark
  • edited December 2013
    I think the different factory theory might have legs, considering like you say, the quality of the work done and Issue 1's and 3's in serial/unserial case combos
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