System 16B - Audio Issue Followed from E-SWAT to Multi

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    • System 16B - Audio Issue Followed from E-SWAT to Multi

      E-SWAT was acquired with dead audio. Converting to the multi did not produce audio either. Replaced the APU with this Z80 from Digikey (I hope that is the correct one). Audio is still dead. Upon turning up volume pot, I get a shrilling sound through the speakers. I can see the voltmeter change consumption as I turn up the volume. Where should I go from here?
      1. Replace sound amp
      2. Recap
      I have no probe yet. Thanks!
    • acblunden2 wrote:

      Great rule! Are the previous 742 rules just as fantastic?

      Probe is on the way.
      They are all amazing! Here's a sample:

      Repair rule #32: If it suddenly smells delicious, you are probably holding your soldering iron incorrectly.

      Seriously now, if I have the time I'll do a repair tips series... But that's a big if.

      When you get your probe I'll help you learn how to use it. It's important to know this, especially when doing remote diagnostics.

      Can you send a picture of the area surrounding the Z80? I want to check what type of RAM it's using.
    • I have the same issue, although my Sys 16 PCB was working with full sound when I put the Multi on it. My PCB is from Shinobi, which I know have flaky Z80s, so I am hoping it is just that...
      Collector for 25 years - New from '92 - Electrocoin Xenon SFII CE - Over 150 original PCBs - Darksoft Multi CPS2/Taito F3/Neo Geo MVS+AES/Irem M72/Sega Sys16 - JROK multi Williams
    • The SRAM you have next to the Z80 (TMM2018) is known to be a... crappy kind of RAM. I don't know if the System 16 tests the Z80 RAM but I'd guesstimate that if it does it will mark it as BAD/NG. (Did you run the test mode?)

      It's a very common part and can be replaced by any 6116 SRAM (2k X 8). If you don't have experience desoldering, don't try. It's likely you'll make it worse.

      When your probe arrives we can do some testing to make sure it is that one that went bad.


      @LHantz this may also apply to your board.
    • ic3b4ll wrote:

      The SRAM you have next to the Z80 (TMM2018) is known to be a... crappy kind of RAM. I don't know if the System 16 tests the Z80 RAM but I'd guesstimate that if it does it will mark it as BAD/NG. (Did you run the test mode?)

      It's a very common part and can be replaced by any 6116 SRAM (2k X 8). If you don't have experience desoldering, don't try. It's likely you'll make it worse.

      When your probe arrives we can do some testing to make sure it is that one that went bad.


      @LHantz this may also apply to your board.
      Sound RAM isn't tested (not accessible by main CPU), however you are right, I was about to suggest to have a look at the sound RAM.
      Looking for:
      - faulty Space Harrier or Enduro Racer
      - Super Nintendo CPU (3 needed)
      - Sega trackball I/O board 837-8685 (will be reproduced and gerbers made freely available)



      "I'd 1cc games but I have a real life."
      01010011 01000101 01000011 01010010 01000101 01010100 00100000 01001101 01000101 01001110 01010101 00100000 01000111 01010101 01011001
    • acblunden2 wrote:

      I am good with desoldering. I have a Hakko FR-301 too. Question about the probe as I am awaiting its arrival. The 5v rail that I have to hook it up to can be anywhere between the PSU and PCB?

      I'll run test mode and see if I get a RAM error and report back.
      Desoldering is probably the best skill to have in practical terms when it comes to repairs so consider yourself in luck :)

      Regarding the probe, it doesn't really matter where you take the 5v from. You don't have to take it from the PSU.
      For ease of use I just made a small hook with a resistor leg and soldered it to the JAMMA connector on my bench and did the same for ground on the opposite side.
      This way it's close to the board and easy to move around, while having similar voltages to what the board has. TTL voltage levels are a fair bit lower than 5v for a logic high, so voltage drop doesn't really matter much.

      Repair rule #15: insulate the logic probe so that only the tip is exposed or you will short something when you use it.
    • It's not the Z80 on mine either, I just swapped with a known working from Alien Storm. Mine clicks when it is switched on, and I can hear buzzing from the speaker when it is turned up, but just have no sound at all
      Collector for 25 years - New from '92 - Electrocoin Xenon SFII CE - Over 150 original PCBs - Darksoft Multi CPS2/Taito F3/Neo Geo MVS+AES/Irem M72/Sega Sys16 - JROK multi Williams
    • LHantz wrote:

      It's not the Z80 on mine either, I just swapped with a known working from Alien Storm. Mine clicks when it is switched on, and I can hear buzzing from the speaker when it is turned up, but just have no sound at all
      Rub your fingers under the amplifier section. Do you hear a buzzing noise? The amp is good.

      The tips I'm giving to @acblunden2 seem to apply to you too, so keep checking the thread. Get a probe! :)
    • ic3b4ll wrote:

      Desoldering is probably the best skill to have in practical terms when it comes to repairs so consider yourself in luck :)
      Regarding the probe, it doesn't really matter where you take the 5v from. You don't have to take it from the PSU.
      For ease of use I just made a small hook with a resistor leg and soldered it to the JAMMA connector on my bench and did the same for ground on the opposite side.
      This way it's close to the board and easy to move around, while having similar voltages to what the board has. TTL voltage levels are a fair bit lower than 5v for a logic high, so voltage drop doesn't really matter much.

      Repair rule #15: insulate the logic probe so that only the tip is exposed or you will short something when you use it.
      Cool. I am putting together a PCB for testbench/repair purposes. I do mostly CRT monitor repair, but am trying to learn PCB repair. I have test point clips on the +5v line. The test point clip near exposed metal is ground and the nearest exposed metal is also ground.

    • @acblunden2 it looks really good!

      Don't forget to add a voltage divider to attenuate the audio or you'll likely blow the speaker.

      It's also a good idea to use copper pours for the power and ground.
      If you're using kicad I can help you with this.

      PCB repair is a lot more involved than CRT repair I think. LOTS of studying to do regarding digital and analogue circuits. With that said, go for it, there's a huge lack of repair techs :)
    • I am using EasyEDA. Earlier version of the board had a copper plane for ground, but I couldn't get auto routing to work with this version. I think I have to take it back to the drawing board though because I would like to add a ST3T switch on it for the voltmeter (one meter to display/calibrate all three voltages). Plus, you are right, I should add some circuitry to attenuate audio for the onboard speaker. There is just a switch to channel the "speaker +" from the onboard speaker or to route it to a connector for external audio connection right now. I think I would have tried PCB repair sooner, but the wiring mess from my test bench has always prohibited me. Always desired just some device with tiny momentary switches for the few button presses needed for test bench purposes. Hence the PCB.

      The plan is fasten an ISO transformer (CRT repair), a switching PSU, and a GBS-8200 (modded w/GBS control) to a 12x8 wood plate with an AC switch. Fasten a handle to the edge of the wood plate so I can be portable. There might be enough room left on the wood board to add in a small LCD screen for when I need to be portable (test boards that I hope to buy out in the field).

      The probe came in today. But as now, no test bench =). I'll figure something out so I can probe the 16B using one of my cabs.
    • acblunden2 wrote:


      The probe came in today. But as now, no test bench =). I'll figure something out so I can probe the 16B using one of my cabs.
      This is a truly gem sir ! this probe model is awesome ^^
      Multi's: CPS2 / F3 / M72 / NA1-2 / System16 B / Namco System1 Vector Labs' 4 in 1 (Horizontal)
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    • ic3b4ll wrote:

      PCB repair is a lot more involved than CRT repair I think.
      That's a joke I have with some friends doing chassis repairs only. I tell them I'm also repairing chassis when I want to have a break and go back to something easy. :P
      Looking for:
      - faulty Space Harrier or Enduro Racer
      - Super Nintendo CPU (3 needed)
      - Sega trackball I/O board 837-8685 (will be reproduced and gerbers made freely available)



      "I'd 1cc games but I have a real life."
      01010011 01000101 01000011 01010010 01000101 01010100 00100000 01001101 01000101 01001110 01010101 00100000 01000111 01010101 01011001