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midibob last won the day on January 8

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About midibob

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  1. midibob

    Pc92 help please

    IC1 deals with the switch returns and the reel motors. The LCD display is handled by IC4 & 5. These are all Z80 PIO chips. It's all in the manual.
  2. Just to add, this one has one of the 'new' sensors put in and it now works a treat.
  3. Yep, pretty much the same as the MPS1 except that uses a 555.
  4. Yep, it's the opto which is nearly always the most difficult bit to find. Still these ones look almost new condition wise so they will be handy for spares. It's the same for the TIL143's. Places do sell them but they are usually listed as equivalents and they aren't! The transistor (receiver) is the opposite way to the 143's which isn't a problem on the ones that just have the sensor as you can swap the wires around. On the ones with the added transistor, they won't work!
  5. The box of Electrocoin (Starpoint) sensor boards arrived and, as they have the same connector as the MPS1, I plugged one into my tester and it works as expected which is great news. I'll do a vid of the tester when it's finished as it's going to be quite a handy device to do a quick check.
  6. The two semiconductors. The plastic case comes apart and the two devices slide in. One is an IR emitter diode and the other a IR light sensitive transistor, both have two legs which in the transistors case you can imagine the light source is the base of the transistor. Hope that makes sense.
  7. Thanks Nick, doesn't surprise me. Pity you can't get the inserts either, although there is an Ebay item for someone in Australia but they might not get here till April!!
  8. Thanks for all the replies chaps. I was really looking for new replacements as it's for workshop repairs. That's the trouble with all this obsolete stuff. I think the best bet is the Ebay ones as they look in pretty good nick. Didn't think to look for populated boards! Thanks for the offer Scooby but I've bought the ones on Ebay so no need to send one. I've built a small test unit to check reel sensors, SYS80 types and SRU and MPS1. It's almost finished just needs the art work done. Nick lent me an MPS1 sensor board but it's got a knackered emitter hence the reason to get a good
  9. Hi chaps, A little poser! Has anyone swapped out an MPS1 reel sensor opto switch if so what did you use? I've been searching on and off the last couple of days and can't find anything suitable. The originals appear to be obsolete albeit I don't really know what the part number it is. Here's some pics... I've looked up OPB520 but with no success. The slot is about 10mm and it does come apart but I can't find any suitable inserts for it either. The manual states it uses an MRD721 and a MLED71 both of which are obsolete! Most inserts I've found have a dome le
  10. midibob

    Mpu3 burnt plug

    They are still available (I think) either from Mouser or Digikey but they have to be imported from the States.......... Just checked and unless you buy about £5k worth you're out of luck. I do hold a small stock and can sell 10 for pound which is pretty much what I paid for them. Let me know if you are interested.
  11. midibob

    Mpu3 burnt plug

    Crimping the pins is the easy bit! Getting the old ones out is the tricky bit. In this case you don't have to so it's not a worry. I think I used to use my Molex tool, which made a good crimp albeit these are AMP connectors. These are far too expensive for a small one off job like this. There are plenty of others on Ebay varying from absolute rubbish to not too bad. Check out https://www.youtube.com/watch?v=DXLmuDbcLBM&t=8s In quite a few cases the actual male pins in the board connector have had it and replacing the females, although a lot better, won't last the test of time. I'
  12. I'd give the board a good clean too! If there's any deposits from the old RIFA's stuck to the board make sure you remove them as they can be conductive.
  13. Nope, you can search straight off of Google and find it.
  14. Have you done a search on the forum as you might find a clue.
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