Leaderboard

A quick fix that took an awful lot longer than it should of done. The board was alarming and the watchdog was tripping. You have to be careful with these boards as it's so easy to go chasing your tail all over the place and end up getting nowhere. Ater wasting many hours looking for a watchdog fault it was nothing to do with it, the watchdog failure was a symptom not a cause. You can disable the watchdog with a link (refer to the diagram). After a bit of sanity returned I eventually found that EN2 which is fed from IC16 (74LS139) showed no output. Once this was swapped out it all burst into life.

The ghost from Christmas past visited the other day in the shape of SYS83 board and it's been giving me nightmares ever since. This particular board I worked on a while back (on the previous page) and I did a repair to the track. The board was returned with a fault of almost booting but not completely. On test it would come out of RESET OK and boot up to all the lockouts energising and then immediately going back into RESET ad infinitum! The problem was the watchdog was firing off but it's taken me the best part of a week to find out why. I changed all the components in the watchdog circuit but it didn't cure the fault. After chasing my tail for a few days I noted that the watchdog 100Hz waveform became very noisy as soon as the boot cycle completed and this is what tripped the RESET. This all happens in a fraction of a second so the only way to monitor it was to disable the watchdog by shorting out the base of TR3 to ground. It was then apparent there was another wave form on top of the watchdog one which was tripping the RESET. Next step was to trace it back and find out where it was coming from. The watchdog pulse is generated from IC43 and it was noisy leaving this chip. This chip had already been changed from the last repair and of course a new one made no difference. Attention was then directed to the supply rails of the chip which were also very noisy! Suspecting there could be a bad supply rail somewhere the scope was moved to the cap in the pic and guess what, no noise? Moving the ground lead of the scope to the left where the repair was done and the noise was then showing. A quick check with the Ohm meter showed it was 0 Ohms but the scope said it wasn't directly connected! So to cut a very long story short what had happened was the copper by the cap was obviously still rotting so a link wire was put across from the cap lead to the new piece of track. When checked again the noise was minimal and what do ya know it didn't trip the watchdog any more. Job done. When Jacob Marley visits again I'll repent all my sins after that one.

Hi Guys I am pleased to release my redraw of the old 2p Silver Shuffle. This was our favorite 2p machine back in 82 and is still a really great game by today's standards. Unfortunately nobody ever found a picture of the original machine, until the George Wilson arcade pictures turned up, and even then the view of this machine was sideways on. Anyway, after drawing the Red shuffle, and converting it back to the original blue version, I only had to use my memory to convert that to the Silver Shuffle that I remember. Hopefully you will enjoy giving this some play! Thanks to @launton for the extremely rare 2p ROMS, @alex74 for play testing, and Wizard for his MFME:) Here is the download: Silver Shuffle v1.0.zip Have fun everybody.

I ordered a box of 5 tubes from China off of Ebay years ago. Curable solder mask is the stuff, comes in lots of colours now and there's lots of UK sellers too.