Results 1 to 4 of 4

Thread: Spectrum 48k Mainboard Rev 5 or 6

  1. #1
    Only Amiga Makes it Happen Amibayer!
    Staff Moderator
    manic23's Avatar
    Join Date
    Apr 2013
    Country
    United Kingdon
    Region:
    Bromley, Kent
    Age
    49
    Posts
    2,339
    Feedback
    154 (100%)

    Default Spectrum 48k Mainboard Rev 5 or 6

    I am after a working rev 5 or 6 Spectrum 48k Mainboard for the rubber key version, does anyone have a spare for sale?
    Last edited by manic23; 3rd April 2017 at 21:28. Reason: Found
    Commodore Amiga A600 - A601 1mb RAM Upgrade
    Commodore Amiga A500
    - A501 512k RAM Upgrade
    Commodore Amiga A1200 - Blizzard 1230 IV, SCSI Kit & FPU - 128mb Fast Ram
    Commodore Amiga A4000 - Picasso IV - X-Surf 100 - Rapid Road USB - WarpEngine 4040 & 128mb Fast Ram

  2. #2
    Repairer Extraordinaire Amibayer!
    AmiDev
    Administrator
    TheCorfiot's Avatar
    Join Date
    Mar 2008
    Country
    UK
    Region:
    Wales
    Age
    52
    Posts
    8,960
    Feedback
    230 (100%)

    Default

    Whats wrong with your original board matey ?
    Ritchie Blackmore's Rainbow June 2016, I Was There

  3. #3
    Only Amiga Makes it Happen Amibayer!
    Staff Moderator
    manic23's Avatar
    Join Date
    Apr 2013
    Country
    United Kingdon
    Region:
    Bromley, Kent
    Age
    49
    Posts
    2,339
    Feedback
    154 (100%)

    Default

    Quote Originally Posted by TheCorfiot View Post
    Whats wrong with your original board matey ?
    Long story!! I have a revision 2 board at the moment that has issues with a device I use called the Spectra 128. It's an expansion devise that enables RGB out and has a rom socket on it, you can plug in a device called the ZXC4, this is a programmable ROM that has 4 mb storage.

    Games crash and hang a lot using this device with my rev 2 and apparently it is to do with the clock line on the Spectrumís expansion bus, which Spectra uses to synchronise its picture output with that of the Spectrum. This signal is notoriously poor, it should have square pulses of amplitude 5V but on some Spectrums it can be extremely low (2V or less) and very noisy. The Z80 CPU can cope but if an interface is connected that also uses the clock line then the voltage can drop lower still and potentially below the voltage level where the Z80 can reliably detect it.

    Sinclair published some fixes for this problem, but it is a BIG job, lots of components to change, I think that replacing it with a rev 5 or 6 that does not have this issue might be cheaper and easier in the long run.


    Sent from my iPad using Tapatalk
    Commodore Amiga A600 - A601 1mb RAM Upgrade
    Commodore Amiga A500
    - A501 512k RAM Upgrade
    Commodore Amiga A1200 - Blizzard 1230 IV, SCSI Kit & FPU - 128mb Fast Ram
    Commodore Amiga A4000 - Picasso IV - X-Surf 100 - Rapid Road USB - WarpEngine 4040 & 128mb Fast Ram

  4. #4
    Only Amiga Makes it Happen Amibayer!
    Staff Moderator
    manic23's Avatar
    Join Date
    Apr 2013
    Country
    United Kingdon
    Region:
    Bromley, Kent
    Age
    49
    Posts
    2,339
    Feedback
    154 (100%)

    Default

    Found elsewhere, closing thread
    Commodore Amiga A600 - A601 1mb RAM Upgrade
    Commodore Amiga A500
    - A501 512k RAM Upgrade
    Commodore Amiga A1200 - Blizzard 1230 IV, SCSI Kit & FPU - 128mb Fast Ram
    Commodore Amiga A4000 - Picasso IV - X-Surf 100 - Rapid Road USB - WarpEngine 4040 & 128mb Fast Ram

Similar Threads

  1. Closed Amiga 4000T Mainboard A4000T Mainboard
    By holzroller in forum Found Archive
    Replies: 4
    Last Post: 25th August 2015, 19:39
  2. Wanted Sinclair Spectrum ZX 48K - Mainboard Issue 3
    By YuT666 in forum Sinclair
    Replies: 0
    Last Post: 10th May 2015, 03:17
  3. Closed Spectrum 48k mainboard
    By soeter04 in forum Found Archive
    Replies: 3
    Last Post: 3rd March 2014, 10:41
  4. Replies: 7
    Last Post: 8th May 2013, 06:37
  5. Closed A600 mainboard and Two A500 mainboard
    By seko in forum Sales Archive
    Replies: 14
    Last Post: 12th March 2012, 07:28

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •