Leaderboard

I miss my fringe and younger minge.

Going back to the previous board that needed the two darlington driver chips replaced (ULN2823) I managed to source some equivalents, more of this in a mo. Anyway, new chips arrived, plugged in and all lamps were restored which was a relief. On soak test though things started going wonky eventually ending up with intermittent then no reel drive! When running the diagnostics this shows up not only by trying to run the reel tests but also the switch tests. Basically the software just locks up and a reset/power cycle is the only way to get it to start again. All the other tests run OK. So what's going on here? The reels are controlled by the TMS7041 CPU which talks to the main CPU through the aysnc controller chip TMS9902 via the peripheral communication link. After swapping out the 9902 the fault was still present so that was a relief. Real 9902's are getting very difficult to source for a reasonable price. Next I got the scope out which I should of done originally and stuck it on the peripheral com line. Data should be flowing both ways on this link but it was only going in one direction from the main CPU to the reel CPU. This proved to be IC17 (74LS09) having a bad gate. The chip looked absolutely perfect and had been running fine ever since I started on this board? Just goes to show. Putting in a replacement and things were back to being hunky dory. Going back to the ULN2823's, these were like the proverbial hens teeth and with a price to match! After a bit of web surfing I came across an ST device L603 which is exactly the same spec and these are a lot cheaper. I got some from a Polish seller on Ebay and the chips look good (and work) so I'm happy about that. As far as repairs go I'm switching off for the rest of the day and putting on my Bob the Builder hat for house refurbishing. There's no peace for the wicked!!

Donations help....in more ways than one. Like everything else in life though..... What you put in depends on what you get out. If you are serious about joining the forum and not just for repair advice etc,there is a mountain of advice and help if you are willing to contribute yourself.

All minge😆😂😆😂🤣😆🤣😂

...and being put into storage without taking the batteries off!

Its a forum!!!! people have lives! people have the choice of weather they answer a particular question or not!! It is not a requirement!! good luck in your quest