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midibob

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midibob last won the day on July 4

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  1. It's very difficult to tell from pictures but I would imagine if you are careful when inserting it you might get away with it. That will start all the double entendres off I'm sure.
  2. Hmm, on a closer look I'd say maybe not. The non 3M one looks like it's for soldering onto the PCB rather than fitting in a socket? Could be wrong though?
  3. Something like this? https://www.toby.co.uk/cable-wire-to-board/254mm-idc-connectors/606-valcon-254mm-idc-dual-in-line-male-headers/
  4. Well done, nice to see it all up and running.
  5. As CanonMan says to take on just one board and especially with no info, diagrams etc, it's not for the faint hearted. I would offer but I've still got far too much on at present. Depending on how much of a hurry you're in maybe in a couple of months if that's any help.
  6. First thing to check is the 5v reg (7905CT) which should have 12v ish on one side and 5v on the other (centre pin is ground). If there's no 12v then you need to check backwards towards the machine. It may come via those diodes (D12-15) and then from the RJ45 connector. If there's no 5v and the reg is getting hot then you have a short on the board somewhere, if it's cold the reg had blown.
  7. I assume the red ones are LED's not lamps and if the display is dead maybe the 5v regulator on the board has blown? It could be a bad caps issue but we'd need to see the top side to make a judgement.
  8. That's good to know as they are pretty rare beasts. I don't know the in's and out's of this tech, probably 80's but I'm sure someone will chip in if you'll excuse the pun.
  9. This tech has been on hold since last year as a project for this year. As if I needed more work. An interesting tech, all built into a frame case with plug in circuit boards. With each new tech a tester has to be built otherwise it's almost impossible to check everything. This time I'm building a hybrid one to test Black Box as well so the old adage of killing two birds with one tester is apt. Anyway down to the nitty gritty. The main issue with these boards is the CPU card as corrosion is rife from the onboard battery. Luckily it doesn't spread to the rest, certainly not in the few examples I've seen so far. So starting with the board on the bench it looked like this... First thing is to strip off 'all' the old components. Sounds easy but it took nearly two days to get all the bits out as most of the solder had gone grey and crumbly. All the connector pins were green so they had to come off too. Fingers crossed the CPU is OK but you can see it has a sort of 'rainbow' effect on the top and in my experience that is usually caused by it overheating! Unfortunately with jobs like this some solder joints just won't let go of their component and what's left of the via and pad comes off with it. I wouldn't even attempt working on a board like this without my rivet kit! With new rivets in, a good clean up and application of solder mask it was time to put the new bits in. I had to add a small piece of copper to the battery track as it had eaten through on the top side. I made a deliberate mistake above. Don't worry I corrected it later. Nearly all done. Sort out a new set of chips barring the RAM and CPU. I'll keep my fingers crossed they work otherwise it's going to get expensive. The only bits I'm short of is the two mica caps that tune the crystal and the 7442 chip which I didn't have in stock. Hopefully they should arrive in a couple of days. Knowing what I know now I don't think I'll be taking on any more corroded CPU cards as this one has taken the best part of three days! Oh, I forgot I've got another one to do.
  10. 96 way headers....ouch! 64 way ones take a fair while to do especially if there's any crumbly solder. Did you use a desoldering gun?
  11. That's what I paid for mine and I did have a good look around.
  12. A mere youngster.... I couldn't even attempt SMD stuff without my microscope, not that I do much of it, so hats off to you.
  13. How about RS? https://uk.rs-online.com/web/p/crimp-contacts/1895981/ .....and you've only got to buy 40,000.
  14. The MPU4 video manual is available in the downloads area but you'll need to become a donator to obtain access.
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