• CIA Chip hack

    From Allen Prunty@1:2320/100 to Dave Drum on Mon Jun 6 03:48:50 2016

    On Jun 05, 2016 07:09pm, Dave Drum wrote to Mark Lewis:

    Dave,

    I don't know if this will fix it but I have access to a couple of broken C64s that may fit the bill.

    Allen

    ---

    This text file describes what to do in order to fix Amiga 500(if one
    of the CIA's is dead) with the parts taken from broken Commodore 64.

    I SHALL STATE THAT THIS IS A HACK, ITS A HACK! ITS A HACK!!! HOWEVER
    CONFIRMED, IT WORKS FOR ME.

    ---

    OPERATION:

    So lets start. If your Amiga 500 has one of the two CIA's dead then you
    can fix it for OS use and some rare NDOS games/demos. There are two such chips(8520A), one labelled ODD CIA (A) at U7 and the second one EVEN CIA
    (B) at U8, they are both socketed. The simpliest method to check which
    one is dead, if Miggy does not start at all, is to remove the B one and
    power it on. If it does start and shows up the so famous floppy screen,
    then its obvious B died. But if it does not display anything then you put
    B in place of A and try again, and if it does start then you leave it
    there and go to strip the replacement chip from broken Commodore 64.

    Note, if swapping chips does not work then you can stop doing anything
    further as this may not
  • From Dave Drum@1:261/38 to Allen Prunty on Mon Jun 6 07:44:24 2016
    Allen Prunty wrote to Dave Drum <=-

    I don't know if this will fix it but I have access to a couple of
    broken C64s that may fit the bill.

    Allen

    ---

    This text file describes what to do in order to fix Amiga 500(if one
    of the CIA's is dead) with the parts taken from broken Commodore 64.

    I SHALL STATE THAT THIS IS A HACK, ITS A HACK! ITS A HACK!!! HOWEVER CONFIRMED, IT WORKS FOR ME.

    8<------- EDITING BEING DONE HERE ----->B

    In C 64 there are also two CIA's and they are at (locations according
    to new pcb) U1 and U2 they have printed 6526B on them. So now you just need to desolder one of them or both, clean up the pins and put in your Amiga in place of B one. The pinouts are same so nothing can go wrong.

    Unless you leave the hot iron on them too long. Many of the chips from the C=64 era were VERY heat sensitive. And never mind how I know that.

    There are several mothods to strip the chip from pcb. I used ordinary soldering iron and the simple sucking device to pick the tin. If you
    got no such tools then you may use simple handy gas burner directly on
    the pins from some distance. But before doing this set the nozzle not
    to cut but to distribute the heat smoothly. Then try to toggle the
    burner form one side to another and if you notice tin melting grab the
    ic - be cautious its hot! Also, dont heat the chip too long!

    As I said above. Bv)=

    DOWNSIDES:

    This, of course, if for an A-500. It seems to me that I was told the A-4000 has soldered in CIAs - and it may well be touchier on its specs. I did a newbie trick of plugging a printer into the parallel port whilst the Miggy was "live". And then it was dead. FEH. Stupid bastard.

    Anyway - thanks for the info. I have several C=64s laying about. Most work .... but, how many 64s does a sane person need?

    ... "All constants are variables." - Murphy's Law of Mathematics

    --- BBBS/Li6 v4.10 Dada-2
    * Origin: Prism bbs (1:261/38)