On 12 Jan 2012, at 15:18, Dave Park <[email protected]> wrote:
> On Thu, Jan 12, 2012 at 8:36 AM, Dilwyn Jones > <[email protected]> wrote: >> From: "Rich Mellor" <[email protected]> >> Sent: Thursday, January 12, 2012 12:27 AM >> To: <[email protected]> >> Subject: [Ql-Users] QXT-640 Revived >> >>> I have managed to revive a Sandy QXT-640 computer - and have listed it on >>> sellmyretro.com >>> >>> Just for the fun of it, I have included a note of my trials and >>> tribulations in getting the computer back up and running. >>> Don't laugh too much !! >>> >>> >>> <url:http://www.sellmyretro.com/offer/details/RARE_Sandy_QXT-640_%28Sinclair_QL%29_Home_Computer-2082> >>> >> Wonder if Dave P. would remember the info about these as he used to work at >> Sandy? >> >> Dilwyn Jones >> _______________________________________________ >> QL-Users Mailing List >> http://www.q-v-d.demon.co.uk/smsqe.htm > > The only aspect of the QXT-640 I dealt with was that all the cards had > the 7805 regulators removed and links inserted as the boards were > given a clean 5v supply. It was a trap and bane of my existence that I > had to carefully check any card I worked on to see if it had been > adapted for a QXT-640 - inserting it in a regular QL would instantly > destroy it. > > I recall the order of cards was important, but not what order, or why > it was important - though anyone who has ever designed a backplane > knows the importance of buffering and signal integrity ;) *winks* I suppose I am a recipient of a wink. Dave is currently making up the last of my Mplane pcbs. Mplane design was strongly influenced by Nasta. There were plenty of pull- up resistors and smoothing caps. The extensive ground plane was vital. I have no solid evidence, but I always assumed SGC etc had to be closest to the motherboard. -- [email protected] http://firshman.co.uk Voice: +44(0)1442-828254 Fax: +44(0)1442-828255 Skype: tonyfirshman TF Services, 29 Longfield Road, Tring, Herts, HP23 4DG _______________________________________________ QL-Users Mailing List http://www.q-v-d.demon.co.uk/smsqe.htm
