Learning repairs :)

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    • Learning repairs :)

      Hi ! got a friend who has one of these babies that he wanted to give me.
      Its only missing one cable. He has no use for it anymore along with a frenquency maker (...do not know if its the right name for it)

      i wanted to start learning the repair ways, having already some working PCB you never know when it will come in handy.
      I know i would surely need some logic probe and chip rewriters.

      Anyone know of a good starting place to learn ? or maybe a good youtube video ? (i don't mind english or french)

      oh and here's the oscilloscope
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      8o My Arcade collection - I'm having fun creating aluminum cases, if you're interested to look at them or have one, drop in have a look !

      arcade-projects.com/forums/ind…thread/8924-astérix-case/
    • One resource I've used is this page:

      wiki.arcadeotaku.com/w/Game_Board_Repair

      It's a neat summary of a lot of things that comes in handy.

      I use a lot of repair logs from various website as well, even though sometimes it goes too fast or becomes too technical for me, I take notes and look up what I don't understand (it's a slippery slope). Google is pretty good at pointing at the blogs/sites of some of our members here :P


      For looking up replacement parts, you can use this handy website:

      https://octopart.com

      Digikey.com or Mouser.com are good for a range of supplies, buyICnow.com and Ebay/Aliexpress for some other chips.


      While I am at it, using this thread as well then as I am slowly going into it for a question :)

      • Any tip on where is best to use the crocodile clip of a logic probe? Ground is usually easy as it's on the edge of the jamma connectors, but for the 5v it can be trickier (most of the videos related to jamma PCBs have it out of the field of view so I cannot really see if there is a best practice).
      Multi Systems: Sega STV + DS Multi | CPS2 + DS Multi | CPS3 + DS Multi | Taito F3 + DS Multi | MVS + DS Multi | Naomi 2 + Pi Netboot | Atomiswave | Taito G-Net + 2011 Bios | Taito TypeX2 + Niko Multi | M72 + Apo Multi
      Cabs: Tecmo Kyotaro | Tekken 5 NNC

      The post was edited 1 time, last by Takosuke ().

    • ShootTheCore wrote:

      For the 5V source, I recommend purchasing a test clip. You can attach the clip easily to any of the chips on the board, and then attach the crocodile clip to the appropriate point on the top of the clip.

      The clip also makes it safer and easier to test the legs of a chip with a logic probe.
      Something like this? Connecting the banana to the Alligator? Seems like I would need some kind of isolation to make it safe, no?
      Multi Systems: Sega STV + DS Multi | CPS2 + DS Multi | CPS3 + DS Multi | Taito F3 + DS Multi | MVS + DS Multi | Naomi 2 + Pi Netboot | Atomiswave | Taito G-Net + 2011 Bios | Taito TypeX2 + Niko Multi | M72 + Apo Multi
      Cabs: Tecmo Kyotaro | Tekken 5 NNC
    • That looks convenient, but I assume you need to purchase a bunch of them depending on type of IC you're looking at then (8, 16, 24, 28, 32, 40, 42, 48...)?
      Multi Systems: Sega STV + DS Multi | CPS2 + DS Multi | CPS3 + DS Multi | Taito F3 + DS Multi | MVS + DS Multi | Naomi 2 + Pi Netboot | Atomiswave | Taito G-Net + 2011 Bios | Taito TypeX2 + Niko Multi | M72 + Apo Multi
      Cabs: Tecmo Kyotaro | Tekken 5 NNC
    • You can clamp a longer clip over a shorter chip and leave the excess hanging off the end. Likewise, you can clamp a shorter clip over a longer chip, probe those points, and then scoot the clip further down the chip to the next set of points.

      Anyway, if you just want a secure 5V mounting point for your logic probe power, pick up a short clip and use it just for that purpose. A clip isn’t necessary for probing chips, but it does make it easier to avoid accidentally slipping with the probe tip and shorting two adjacent legs together.
    • Escarioth wrote:

      frenquency maker (...do not know if its the right name for it)
      Frequency generator is the term you are after


      ShootTheCore wrote:

      I was thinking of an IC Test Clip like one of these:

      digikey.com/product-detail/en/3m/923690-16/923690-16-ND/3840
      Oh nice pretty handy for older devices . I did google about test clip for smaller packages and came across this thread

      eevblog.com/forum/beginners/an…-grabbers-for-my-package/

      where someone recommended these warwickts.com/1710/E-Z-Hook-X2015-Double-Micro-Hook which are good to 0.5mm pitch

      The post was edited 2 times, last by tiff_lee ().

    • Continuing on the general topics: When would using an oscilloscope be preferred to a logic prob for a diagnostic? I understand that they can be used in different ways, but what would make me say "Ok, I tested it with a Logic prob, but I would want to use the scope to..."?

      (Thinking about compiling all the info on this thread to make some FAQ or something that we should stick somewhere :P)
      Multi Systems: Sega STV + DS Multi | CPS2 + DS Multi | CPS3 + DS Multi | Taito F3 + DS Multi | MVS + DS Multi | Naomi 2 + Pi Netboot | Atomiswave | Taito G-Net + 2011 Bios | Taito TypeX2 + Niko Multi | M72 + Apo Multi
      Cabs: Tecmo Kyotaro | Tekken 5 NNC
    • A logic probe is best for getting a quick, real-time view of how the circuit is behaving. They have simple indicators lights and tones that indicate whether the circuit voltage is high, low, fluctuating, or nonexistent (aka floating). You can quickly sample a variety of points and know what's going on just by the tone. They are most useful for troubleshooting obvious digital logic issues (like a failed crystal, EPROM, TTL or CPU).

      An oscilloscope is used when you need to perform a deep analysis of how a specific circuit is behaving. You can measure the range of voltage on the circuit mapped out over time. You can save samples off for later review. They are most useful for troubleshooting analog issues (like calibrating a CDROM drive, AV output, CRT or vector graphics displays), and digital troubleshooting as well when you need to see how the circuit is behaving relative to time (ie timing issues) or voltage (ie a logic circuit is fluctuating high and low, but the high voltage isn't strong enough due to deterioration of the chip).

      You can use an oscilloscope like a logic probe and quickly see digital logic behavior, but it's harder to use since you have to initially calibrate the scope for the circuit and watch the display while you probe. A logic probe doesn't require calibration and you can just listen for the tone.

      They both have their uses, but I'd always recommend purchasing a logic probe before an oscilloscope since it's much less expensive ($20 - $30) and is much more useful initially for quickly assessing what's going on around the board.
    • Perfectly summarized, thanks for the clear explanation :) I will definitely try to compile all the cool tips and advice and make a FAQ/guide.
      I got a probe sometime ago and have yet to use it, and no proper workbench or room for a scope yet. All that is incredibly helpful, as reading a lot is great but having the feedback here thanks to you guys is even better.
      Multi Systems: Sega STV + DS Multi | CPS2 + DS Multi | CPS3 + DS Multi | Taito F3 + DS Multi | MVS + DS Multi | Naomi 2 + Pi Netboot | Atomiswave | Taito G-Net + 2011 Bios | Taito TypeX2 + Niko Multi | M72 + Apo Multi
      Cabs: Tecmo Kyotaro | Tekken 5 NNC
    • Takosuke wrote:

      Perfectly summarized, thanks for the clear explanation :) I will definitely try to compile all the cool tips and advice and make a FAQ/guide.
      I got a probe sometime ago and have yet to use it, and no proper workbench or room for a scope yet. All that is incredibly helpful, as reading a lot is great but having the feedback here thanks to you guys is even better.

      yup thanks ! that was indeed very helpful :)
      8o My Arcade collection - I'm having fun creating aluminum cases, if you're interested to look at them or have one, drop in have a look !

      arcade-projects.com/forums/ind…thread/8924-astérix-case/
    • Escarioth wrote:

      Its only missing one cable. He has no use for it anymore along with a frenquency maker (...do not know if its the right name for it)
      I think you're French, we call it GBF (générateur basse frequence = low frequency generator), since those old oscilloscopes only convert electrical signals to something visible on the screen you first need to "calibrate" them with a signal of a known frequency. Then newer models have an accurate time base.

      ShootTheCore wrote:

      20 mhz is indeed pretty slow - most old arcade boards operate faster than that. A 50 mhz scope would be a good baseline, while 100 mhz would be ideal.

      Oscilloscope for repair, help
      20Mhz is more than enough for pre mid 90s boards:
      - System 16/18/24 have main CPUs clocked 10Mhz
      - CPS1 is 10/12Mhz
      - CPS2 is 16Mhz
      - Irem M72/M81/M82/M84/M85 are 8Mhz
      - etc.
      You have to keep in mind most signals have lower frequencies than the CPU clock.
      Looking for:
      - OutRun boardset even untested or not working
      - Sega Super Scaler hardware (Out Run, Model X, Model Y), even with faulty PCM chip



      01010011 01000101 01000011 01010010 01000101 01010100 00100000 01001101 01000101 01001110 01010101 00100000 01000111 01010101 01011001
    • Apocalypse wrote:


      20Mhz is more than enough for pre mid 90s boards:- System 16/18/24 have main CPUs clocked 10Mhz
      - CPS1 is 10/12Mhz
      - CPS2 is 16Mhz
      - Irem M72/M81/M82/M84/M85 are 8Mhz
      - etc.
      You have to keep in mind most signals have lower frequencies than the CPU clock.
      oooh ! really ! that's perfect ! i was sad it wasn't enought :)
      8o My Arcade collection - I'm having fun creating aluminum cases, if you're interested to look at them or have one, drop in have a look !

      arcade-projects.com/forums/ind…thread/8924-astérix-case/
    • Something super useful and not too pricey also, that makes life easier on troubleshooting a board:

      A Digital Microscope!

      I got this one for cheap on Amazon:

      plugable.com/products/usb2-micro-250x/

      The result is quite good for such a low price, and helps spotting bridges, cold solder, cut traces and any tiny defect when inspecting the board or even working on it.

      Multi Systems: Sega STV + DS Multi | CPS2 + DS Multi | CPS3 + DS Multi | Taito F3 + DS Multi | MVS + DS Multi | Naomi 2 + Pi Netboot | Atomiswave | Taito G-Net + 2011 Bios | Taito TypeX2 + Niko Multi | M72 + Apo Multi
      Cabs: Tecmo Kyotaro | Tekken 5 NNC

      The post was edited 2 times, last by Takosuke ().