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Just reading through this thread and remembered an article in the coinslot archives section, not very readable i am afraid but you can make out the gist. Page 1 headline. 1978 17 JUN.pdf

Just recently I've had a fair bit of PC92 work coming in and with lots of new avenues I've never been down before. As always I love a challenge with a tech that I thought I knew all about but obviously didn't. As most folks are aware the Procon tech morphed from the early PCL right up to quite a few versions of PC92 and the multitude of mods inbetween is extensive! It's well known that no documentation for PC92 exists in the wild (although I bet someone is hanging on to a copy!) so the only thing to do is to try and capture all the differences and get them documented. I have collated most, but certainly not all, the differences between the released diagrams and the later versions. These I will upload soon once they are double checked. Most functions are easy to work out but I have found there are some tricky ones. The first one I came across was Theme Park which on the bench would always fire up a stake % key error (402). This could be bypassed by activating certain switch connections on the matrix. I was expecting the normal stake key board to be fitted but on the machine in question there wasn't one? This issue is still outstanding but I'm sure there's a silly reason why the key isn't fitted? The second one involves Chico and this one had me going for a bit. This game has a 4x20 VFD but it's not driven off of the VFD port on the board, maybe it wasn't fast enough, cleverer folks than me on here will probably know. In this case the VFD is driven from the 14 way DIL socket which has a feed from the SIO chip. Another thing to note is the VFD gets its 5v supply from a separate Display PSU board which is powered from a 12v feed from the same 14 way socket. This little board also has a transistor on it which reduces the 20v P2P waveform to TTL levels for the VFD. I have to say all credit goes to Magik as this was all gleaned from a PC92 video he did about a year ago where he came across this for the first time. Had his head scratching too. I will post the diagram for this board shortly. Another thing with the 14 way is it needs a link between pins 3 - 13.

bored, so started thinking about what I know, or think I know about MPU land. Heres me list: MPU TYPES: barcrest machine processor unit - MPU0 techincally, the very first controller- no ram/roms, lots of discrete DTL logic MPU1- first 6800 based unit, still running the earlier mechy reels. MPU1 second revision- diffrent flavour of the same computer- first revision in an ugly two sided case, second revision is one in your picture. MPU2 - early versions mechy reels, later versions steppers. But later programs use the lamp output for the reels, find a board cover you will see what I mean. Its also why lots of MPU2s burn out the reel drive transistors. They arent rated for it. MPU3- Even people who dont follow fruit machines know what mpu3 is- its really that famous/ notorious, a true electronic celebrity- its been around in 7 revisions, some official, some unofficial MOD0- 3 - early boards with small RAM MOD4 - prob no longer exists, had some modifications on the PCB that didnt work, so field engineers modded them back to mod3. MOD5- board revision with bigger RAM and sensitivity circuit added on the PCB. MOD6- adaption of the PCB to use small daughter card with 6116 RAM MOD7 -unnoficial update! uses ZRAM, zero power RAM , and has some other tweaks. A special revision by the meccas MDS- and also a secret, so no telling! MPU4 - 1983 to present day, co existed with MPU3 for a while in the early 80s as well. Is around in 3 versions, alougth officialy theres only 2- MOD2 - origional version (mod1 was factory develpment platform, never released) Has yamaha sound chip. MOD4- second revision (again MOD3 factory prototype and inhouse only) Sampled sound used on program card, socket left on PCB to fit sound chip if desired. MOD MECCA- well you could say that- this one is a board that we have fitted the sound chip back onto. Theres a few in circulation all over now ! MPU3 video- it did exist, but I dont know much about it. MPU4 video - a video computer that plugged into the standard MPU4 (MOD2 mpu4 btw) . Quite an impressive system! MPU5- the current standard for most arcade ops- seems more reliable than rival systems. JPM: jpm pioneered the stepper motor system at a trade show in 1978, so far, to date they have used: electromech reel processor - 1974 till about 1978- quite bellfruitish, 16 relays and 4 cam timers. And electromechanical reels, again similar to the BF unit. SRU - revisions 0-9 - all very similar, the changes to them were very suttle. JPMs first stepper motor system, quite revolutionary in its day, and all built into a handy integrated assembly that plugged into the machine. Used horrible valerco plugs tho that dont have good track record for longevity! SRU overseas revision- SRU board with diffrent layout. Program ROMs on a daughter card with a nicad and a static RAM. Seen in dutch JPM machines and others. Unlike the SRU board in the british machine, this board looks a bit like an early pinball machine processor- square board with plugs down either side. System 80 - SRU based platform with extended outputs, seperate CPU and sound cards and improved interconnects, again all in that handy integrated unit. Some very well known and well liked games on this platform. A good system from JPM and not as difficult to repair as first thought. For years when we had system80 repair threads it was thought that the CPU cards were murder to fix. Now some of them are, this being due to the freindly nicad, but lately paulgee discovered that 9 times out of 10, its nothing more than faulty RAM. He was lucky enough that I found some replacment 5114 for him, but if all else fails, you can use 2114 without a battery backup, or you can make a mod to use 6116. This system generates a lot of heat tho as all the 12v outputs are directly driven , no matrix on these! MPS1- still embracing the TMS family CPUs, but now with a lamp matrix and a number of other improvements. Good system but not a great deal of good games on it. David Powell designed this system, as well as epoch. Its the PSUs that are a minefeild on this tech. If you have an MPS1, and it has a red label PSU, change it for a yellow label. MPS2- MPS1 compressed onto a much smaller board. Lots of discrete logic replaced by 8255 PIAs, but JPM used custom made ones, so they arent marked 8255. MPS2 and MPS1 are backward compatible apart from 1 or 2 games, usuallly BWB ones. SYSTEM5- scary serial IO reel drive JPM system. Crap tech but brilliant games. 2 revisions, one had yamaha sound, one didnt. they arent interchangable. IMPACT- JPM impact is a very nearly perfect fruit machine MPU. All modular, but all contained on a motherboard with edge connectors rather than ribbon cables to off board units. This system is quite robust and has stood the test of time. Early impact machines were in ugly vogue cabinets, later ones in the electra. Impact has had 2 flavours over the years- impact 1, which is the 4 slot motherboard system, and impact 3, where all the expansion is carried out an a single card. Possibly they are compatible program wise, but I have never tested that theory out! HEBER PLUTO5/6 - when SEGA took them over, they started to use HEBER machine controllers. Dont know much about these at all apart from the fact that anyone who knows C programming could develop a heber machine- you can download the dev kit online!

Christ knows how you get to the bottom of these repairs! Quite a skill 👌

Yes, that was the Ace Coin 100 Series.

At the moment,The only early adverts with pic I can find are from 1974 showing Gemini and Kaleidoscope However I have found advertisements in 1976 with a number of listed used Barcrest's. King 40 Crackerjack Spellbound Stuntman Winnerama Solitaire Contrasts Masquerade Extravaganza

so to continue, thats the jist of some of them, theres lots more: Bellfruit Games: Probably *the* origional and best modern machine creator out there, if you take modern meaning the early 70s on. They dominated the electro market in the 70s and 80s, there wasnt an arcade anywhere that didnt embrace the bellfruit machine, but they made some pretty good electronic platforms too.... Black box revision one- Two board sandwich in a metal case, tended to heat up a lot, Could develop some strange and frustrating faults. But a compact little computer, used the standard electromechanical reel system with triacs controlling the stop solenoids. Brought us some of the best known classics like firecracker, upstairs downstairs etc. Black box revision two- Same two board system with an NVRAM card added. Used stepper motors instead of electro reels. Nice machines on this platform, usually in that BFM small cab (two step etc). The internals of these cabs were quite daunting for ops of the day, let alone us collectors! System 83- stroke of genius by BFM, brought us some of the most entertaining games of the day. Good robust tech, and indestructable cabinets! System 85- actually came out in 1984. I know this because I have a system85 machine in a system 83 cab with an 84 date on the inspection sticker. Nice reliable tech it was, straightforward PCB layout, easily repaired then and now. Unlike JPMs etc it used a MC6800 CPU which was common on several diffrent techs of the day so it was easy for arcade ops to repair these. Probably my favourite BFM tech of all of them. System 88/89 (later named scorpion1) This was BFM growing up I think. Games were more advanced, sampled sound made an appearance. Scorpion platform was again very straightforward, but I think they had one or two flaws in the design. Rattly reel motors for one, and why was there airvents cut underneath the lamp resistors? You would think they would have rated the parts accordingly. Nevertheless, scorpion machines wiped the floor with the rolltop MPU4s at the time. Scorpion 2 - came out 1991/92 I think , someone will correct me. BFM made some drastic design changes to the scorpion platform and utilised FPGA chip technology to give their system some decent security, and to simplify some of the PCB design. Ive yet to figure out what this security actually is, I think it was just a case of scrambling the ROM address and data lines or something. Scorpion 4 (scorpion3 I dunno, mabye in house revision) - One of the most bloddy unreliable power supplies in existance came with this platform. Which is a pity becuase the PCB design is straightforward, SIMPLER than scorpion 2 believe it or not, and yet still easy for the hobbyist to repair. Its that damn switching PSU that lets it down, theres scorp4s switched off all over the country that are perfectly good MPU wise but have broken PSUs. I know one arcade alone with 8 machines having this issue. You can also get reel failures through the reel power rails drifting out of range, burning up the reel transistors. Six reel scorp4s are prone to this in particular. scorp 5- too new for me to bang on about!