Leaderboard

Another couple of 12K CPU's have landed on the bench and as per usual they are driving me demented. The first one had more faults on it than you could shake a stick at! Both boards had already been got at which always sets the alarm bells off. Well to cut a really long story short, and it was long I can tell you, the first board had an intermittent CPU, a broken track by it's via, one bad RAM chip, a 74LS245 that had already been replaced but was faulty and lots more crusty components. Each time I found a fault I thought, 'that's it it'll work now'. how wrong I was. Anyway once I got to the end of the list I was greeted with a functioning board. The next board had SIP strips fitted to replace all the IC sockets! This is one of my pet hates and as there were various patch wires on the underside of the board I decided to remove them all so I could see what might be missing underneath. 4 rivets later and some connecting wires to adjacent tracks and with all new proper sockets fitted, a few new resistors things were looking much nicer. Still not booting though. After many hours of checking for shorts, open circuits and general continuity I was still scratching my head. Another fault was hiding and I didn't notice it until I was holding the board and thought, 'my fingers getting hot'! One of the bypass caps on the CPU was leaking and it was getting quite warm. You couldn't make it up... So, I hear you all asking, does it run now? Well unfortunately the answer is no, everything looks like its running but nothing is happening. I must have tapped out nearly every track and checked for shorts everywhere and found nothing untowards. There's always tomorrow and if that fails the Thames is only down the road so I might jump in!!!