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Prototype_uk

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Prototype_uk last won the day on December 7 2017

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  1. A UK supplier has the PIA EF68B21P also known as 68B21, 68B21P in stock currently and has more available to order when they run out of stock. https://www.cricklewoodelectronics.com/68B21.html I have ordered some for my MPU4. They say that they are the Equivalent Fairchild. Hope this helps anyone looking for them like I was
  2. Here is the response I got from Cricklewood Electronics. I have order 6x of them We have the equivalent Fairchild model in stock to your Thomson IC. Some function, same pinouts Please view on our website 68B21 We have 18 in stock and more available
  3. Yes I've also used them many many moons ago. I will get a Logic Probe for sure. With regards to the coin problem it first started with the machine not booting and after power cycling it fired into life. See video Then I found that it stopped accepting coins after it started to warm up after anywhere from 1-5 minutes. At first it was just the 20p coins which it wouldn't accept but then it spread to all coins. I tried a different Mech but exactly the same problem. I reached out to Magik who if you look on the comments of my video said it could be the Switch Matrix and to try another board hence why I am trying to get this eBay special working to see if it fixes the problem.
  4. But how can you tell what ones are fake? Is it just a question of trying them?
  5. Third time lucky? https://www.cricklewoodelectronics.com/68B21.html
  6. DUH, I just realized these aren't the right part numbers. I've been working too hard of late How about these to replace IC3 - IC8? https://www.cricklewoodelectronics.com/6821P.html?gclid=CjwKCAiA24SPBhB0EiwAjBgkhpXJibcZo6dnPKz-1zNrRMCLsNNpYi5u_5VT7Hb380nBWp2jeGk2JBoCgFwQAvD_BwE
  7. Sorry I haven't got a logic probe so I can't' check any activity. If I had a working Test ROM that would be half the battle but as I said in my video which I made for midibob I don't want to blow my actual machines ROM (ANDY CAPP) which is why I got a second hand ROM off eBay to do this testing with this repaired board. Problem is it appears this ROM doesn't work so for all I know the board might boot if I had a working ROM. I might be over cautious but I don't want to blow my Andy Capp ROM testing this board. The reason why I am trying to get this repaired board running is to eliminate the problem I have with my machine which is it has stopped accepting coins. Magik said it could be the Switch Matrix and to try another board so I bought this MPU4 off eBay to repair and use for testing to see if it fixes the fault.
  8. Oh are they not the PIO's? Sorry this is my first time at a repair. Can you point me in the right direction please?
  9. Yes the resistor values are correct. They haven't been replaced either. They are being driven from IC14 and that is getting the signal from IC3. The draw will be from the MOSFETS being powered up continually. I doubt 8 Fets have all failed together so I would suspect it is a fault on IC14 or even IC3 or both.
  10. I just tried that on my other board I know works and it doesn't boot with this cart.
  11. Good advice thank you. Do these look genuine to you? https://www.ebay.co.uk/itm/274346525722?hash=item3fe053c41a:g:9q0AAOSwZDleov8~
  12. I buzzed all of these tracks in this area both sides of the board where the through holes are to check conductivity and they all checked fine. I believe there are only two traces under this IC and both buzz good.
  13. Its strange because if I look at my other board without anything plugged in nothing gets hot in this area even without a ROM connected.
  14. Got ya White plug? No didn't plug that in. I guessed that as my other ROM boots with just the power and display that this one would do the same
  15. Do you know if the PIA's are still available or would I have to get a scrap board for parts? I think I will try changing IC3 (EF68B21P) and IC14 (ULN2803A) Those resistors were getting mighty hot.
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