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midibob

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midibob last won the day on November 7

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About midibob

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  1. midibob

    2732 ROM burning HELP!

    I can always burn you a set if needs be. How many ROMs are there as I can't find that file in downloads? (MPU3/4)
  2. midibob

    Scorpion 1

    Scorpion, 'sting in the tail'. Scorp 1 audio faults have brought many a man to tears!
  3. midibob

    Mpu3 Alpha issues

    Watch out, the Oki version doesn't have the £ sign if I recall.
  4. midibob

    MPU1 reel deck logic

    Thanks guys for that. Dan, that's a bit more advanced than these decks, but good info none the less. Wizard has hit the nail on the head. You know I didn't see the binary representation of the studs although I did guess it was binary. The two wins I've found so far were :- Reel A Reel B Reel C 01000 01000 don't care = 10p (unless it's 11000) (the three MS bits are also don't care) 01000 01000 11000 = 50p LS-MS order. Still yet to find the 20p and £1. Logic would dictate the wins are just on the 2 low order bits but I don't think that was the case? Knowing what I know now I'll check it again. The feature reel (the one in the pic) just has numbers 0-9. This one is a bit more tricky as I suspect it needs to re-read the reel after every step when it does a countdown? For the testing though just the 4 payouts will suffice. Doh! it's just occured to me there's 0-9 twice on the reel which is 20 so that reel makes perfect sense. The other reels may be different, I can't remember as it's a long while since I had my hands on one. Not having a reel set to play with is why I needed the pics. I'm in awe of the guys (or gals) who designed these, simple when it's explained but clever.
  5. midibob

    MPU1 reel deck logic

    Thanks for that Rich, yes I do remember Danno's home brew electro. That was a stunning bit of work. Let's see if he replies. Cheers Bob
  6. midibob

    MPU1 reel deck logic

    Hi chaps, Here's an unusual request. I looking for some pics of the reels of a Bell Fruit deck as used in the MPU1. This is what it looks like. The deck has 6 wipers on each reel, the earlier types only have 4 which I've seen in Ron's electro area. The actual bit I'm interested in is the logic wiring on the back of the reels so I can work out the payout combinations (how all the studs are connected). The end result is to build a reel faker unit with a few switches so I can generate wins with a small test box rather than having to use an extremely rare set of reels. So far I've managed to work out two win combinations but it's taken far too long as I'm clutching at straws. Each reel has a main wiper pole which can select any number of the 5 switched studs and this is the same for all 4 reels. The amount of possible combinations is huge hence why it's taking so long to try and work out. Luckily on these old machines there aren't that many win combinations but a pic of the wiring from each reel should unravel the secrets. So if anyone has a set of these reels in a junk box and could take some pics I'd be very grateful. On the other hand there maybe someone out there that knows the logic map already. Now that would be a chance in a million. Cheers Bob PS. Thanks to Steve for the attached pics.
  7. midibob

    Tales from Midibobs workshop, MPU1

    Got 3 more boards in for repair and the faults are starting to form a pattern. I would say the most common so far are the 723 regulator chip which I've had to change on all three. Breaks in the tracks between the connector pin land and the track. This can be on any of the connectors (and usually is!). Usual cap failure 2200uF 25V as per MPU3 although there's only one. Poor connections on the fuse holders, hardly surprising after 40 odd years! The lamp transistor that drives the speaker (BCX38), this one probably has a harder life than the others. Other things to look out for are missing mica insulators and spacing washers from the two semiconductor devices on the regulator board. Instant short circuits otherwise. Another pair of chips are used in the ROM cart which are M3-7641-5 which I've not seen before. These are ROMs only ie no window for UV erasure. Now a question which shows my poor understanding and that is I have two ROM carts with test software on which have two 2716 chips and both work OK. The links are set correctly of course. The plan was to copy some code from the original ROMs which I've already dumped on to some 2716's so they could be swapped out with the test software. I'm obviously doing something wrong as it appears the board will only read the first ROM. It boots fine takes coins but once the Start button is pressed nothing else happens after the Start lamp goes out until the coin switch is operated again. It also pays change if the 50p coin switch is operated. I've tried putting on the code then filling the space with FF's (which is how the test software is done) but it doesn't see the second ROM or at least that's what I think is happening. I've also tried filling them with multiple copies of the same code but no joy. The ideal thing would be to put it on a single chip but I'm assuming the code would need to be altered? (or would it) Would someone like to educate me.
  8. midibob

    JPM sys80 lamp changing

    The machines that have the extra lamp board, Mystery trail, Suppa Snappa and the like have around 40 lamps in so at a pound a throw it's not viable especially if you then have to buy the actual bulbs too. Out of interest they are T1 1/2 1.2W 12v (or maybe 14v) 100mA. I have seen these in large blister packs but can't find any on the Web. Seems like 10 is the maximum which makes them even more pricey.
  9. midibob

    JPM sys80 lamp changing

    What sort of price did you get the LED ones for? There may be several interested parties if they are cheap enough. I believe these holders also used to be fitted to car instrument panels so if anyone has a breakers yard close by they might be able to source a fair quantity.
  10. midibob

    change machine now refurbed

    Nick, you've got competition. Superb job!
  11. midibob

    Mpu4 board capacitors / parts

    It's just a difference in gain ie the -40 is higher than the -25. For their use as triac drivers it doesn't really matter, unless anyone knows otherwise of course.
  12. midibob

    Bellfruit scorpion 2 board repair

    Nice work Andrew. It's amazing how much copper the battery vapours consume over the years. That ground area has almost separated!
  13. midibob

    Mpu4 board capacitors / parts

    Whoops, I missed T13. I use BC337's as they are generic for most applications. Again I'd change all 8 of them as they do suffer from rot as well.
  14. midibob

    Mpu4 board capacitors / parts

    You can use RS part # 144-1970, that is for 100 units. You can buy them in smaller quantities of course but the price per unit goes up. I'd change all 8 of them as well as they will all rot through eventually.
  15. midibob

    Let's talk tools!

    I knew you'd love em eventually.
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