Leaderboard

Another odd one... After doing the usual component replacements, firing up and running the diags all was good. After this and before the soak test on my Cabaret machine I plug in the 'Strike it rich' game as it uses an alpha. Just to note you can't do this on the earlier mod MPU3's as they don't have enough RAM unless they have the daughterboard with extra wires but that's another story! So back at the ranch, switch on and no boot??? The alpha backlight comes on but no characters also there's no reel spin. What's going on here? Next thing to try was 'Line up' as this is an intermediate game that should run with earlier Mods. This boots and sometimes the reels don't spin properly but then it just alarms. Back in with the diags and everything is 100%? When I first looked at the board it had already been repaired at some stage and IC4 & 5 (6821) had been changed but not using proper IC sockets just single strips. I hate repairs done like this so out they came and new sockets fitted. Looking closely at the 6821 chips I could see they both had exactly the same markings which I seem to recall from pictures on Ebay of Chinese 6821's. A quick rub on one of them with acetone proved they were 'blacktopped' and sanded down so impossible to say what they were originally. Most unscrupulous sellers sell these remarked as 68B21's whereas they are really 6821's and slower so in this case I couldn't see what the point was?? Replacing these with a couple of known good test chips and switching on........exactly the same. So it's off to wild goose territory and because the alpha didn't come on I thought I'd swap out IC6 (6821) and of course it was innocent. After a fair bit of head scratching I started testing with the alpha game again and noticed that when it tried to boot everything on the CPU was running and then just stopped? No reason for it so the only thing I could think of was to change the CPU. Blow me it all worked, I've not come across that before and probably never will again. The two 6821's of dubious parentage were put back in and appeared to run OK. Time will tell on that one.

Hi Alain, The RESET LED should go off after approx 4 seconds. If it doesn't there are many causes as to why. I think most of them will be in my workshop thread. The main thing is that you understand how the RESET circuit works otherwise you'll be going round in circles. Thanks for trying to post the ROMs although the attachment is empty? Keep posting your progress as it will no doubt help others in future. Salut Bob

Hi everyone. Using the parts list, I ordered the components I needed. I'm waiting for them. Meanwhile, I read topics about system one, so many things to read... I removed all the questionable components with damaged legs and I redid the copper tracks with copper in rolls. I hope i will be OK. If I understood correctly what I read, le led on the CPU must firstly light up and then go off if the reboot is correct, is that right ? I was happy to see le led on all the time 😂 The card that I try to restore uses only two eproms. They are OK, a friend of mine tested and copy them. Here are the bin files, maybe useful for someone. Jolly Imperial V.zip

Watch out for the tracks near the battery area being eaten away. It might look good with the solder mask covering it but you may find there's no copper underneath. Crazy but true. Always good to tap out the connections to confirm. Don't want you saying 'zut alors'! Here's one I did a while back with the track repaired and rivets fitted. If your PSU connector sockets are contaminated I would get new ones otherwise you'll end up with many intermittent RESET problems. Bon chance.

Not written up an MPU4 for a while so .... This one came in doing all sorts of odd things before it died so I suggested sending the PSU as well just in case. The PSU was fine and all the caps had a good ESR so that rules that one out. Moving on to the board, most of the components around the battery area needed replacing and anything else with green legs. On switch on it did boot but with garbage on the alpha and then nothing. Luckily there was no track damage which was confirmed by tap'ing out the tracks to the alpha. In fact the only track damage was the negative battery pin which had become isolated. A rivet and some copper sorted that. So where do we go next? The first diag test is the triacs and all was good in that dept being as I'd alread swapped out all driver transistors, the 1nF caps and the zener diodes. This comes from IC8 which also has a drive to the alpha. The other drives to the alpha come from IC3 (68B21) so out she comes, in with a socket and a new one and bingo it now says MPU4 ALPHATEST OK. Are we done? Don't be silly, up comes the 7 seg display then it alarms with something like @@@@@ALARM 7xxxx (some other odd characters). Usually once the alpha is working it will tell you what the next error is but in this case it was garbage. The next thing the diags test is the RS232 and the meters (could be the other way round I can't remember) so I blindly changed the two IC's responsible as neither of them were producing the required outputs (IC7 + IC5 68B21). Next boot up and it's still the same.OK, I have seen a 6840 ALARM around this stage so a quick swap out and ....nope! Next thing switch on again and nothing??? The RESET circuit has failed. Should have swapped out these transistors originally, ho hum. So I'm running out of IC's to change so where next? After being on a few minutes with the alarm sound driving me mental I noticed IC6 was cold whereas all the other PIO's were warm. Hmmm, in with a new one and everything sprang to life. That was a relief.

we have now thanks to @fruitsnappa and @slotsmagic sounds within this layout The Woolpack £10 Dx.zip