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Irem M92 “In the Hunt” PCB – What is the CN6 4-Pin Connector Used For? How Should It Be Wired?

E DOOM

E DOOM

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Title:​


Irem M92 “In the Hunt” PCB – What is the CN6 4-Pin Connector Used For? How Should It Be Wired?


Hello everyone,


I recently bought an original Irem M92 “In the Hunt” (海底大战争) PCB and I'm trying to understand the purpose of the CN6 4-pin connector on the board.


I have attached a photo of my PCB below.


PCB: Irem M92-A-B
Game: In the Hunt / 海底大战争
Board marking: OSC 004170B1


There is a 4-pin connector labeled CN6 near the JAMMA connector.


From what I have found, CN6 appears to be related to the stereo audio / second speaker output, but I would like to confirm this from someone who has the original Irem wiring documentation or has experience with the M92 hardware.


My questions:​


  1. What exactly is CN6 used for?
  2. Is CN6 the output for the second speaker / stereo channel?
  3. What is the pinout of all four pins on CN6?
  4. Which pins are audio + / audio −, and are any of the pins GND or unused?
  5. How is CN6 connected in the original Irem arcade cabinet?
  6. If I want to use the M92 PCB at home, what is the correct way to obtain stereo audio from the JAMMA connector + CN6?
  7. Is CN6 a speaker-level output from the amplifier, or is it a line-level audio output?
  8. Can I connect CN6 directly to an amplifier / powered speakers, or do I need an attenuator or other circuit first?

I am particularly interested in the original factory wiring, rather than a modified/homebrew solution.


If anyone has the original Irem M92 wiring diagram, operator's manual, service manual, or a photo of the original cabinet wiring, I would really appreciate it.


I would also appreciate a photo or diagram showing the CN6 pin numbering and corresponding signals.


Thanks in advance!
ScreenShot_2026-08-08_144408_993.jpg
 
I just measured it, it doesn't carry RGB or audio.
It likely has something to do with the coin counters.
 
Okay, back to the PCB when I have more time :)

The MAME driver actually states:
"CN6: Connector for 2nd speaker (for stereo output)"

Just tested it, and that is indeed the case.

Pin 1 > RA2 pin 4
Pin 2 > GND
Pin 3 > TR3
Pin 4 > Audio (unamplified)
 
Last edited:
I assume it's just an additional speaker output, not a separate channel.
 
surprisingly,
its really stereo - at least to my ears.........:saint:

btw:
are schematics for M92 available.....?
 
Last edited:
Astro X said:
surprisingly,
its really stereo - at least to my ears.........:saint:

btw:
are schematics for M92 available.....?
Click to expand...

According to JAMMAarcade.net (and several article contributors) there are not any available schematics for the M92 (or, there weren't when the article was last updated in 2025.) But, if you scroll down to the bottom of the article, they have a couple schematics links derived from the work on producing an FPGA core for the platform that may help you.
 
unfortunately not,
the required audio section is missing...........
 
E DOOM said:

Title:​


Irem M92 “In the Hunt” PCB – What is the CN6 4-Pin Connector Used For? How Should It Be Wired?


Hello everyone,


I recently bought an original Irem M92 “In the Hunt” (海底大战争) PCB and I'm trying to understand the purpose of the CN6 4-pin connector on the board.


I have attached a photo of my PCB below.


PCB: Irem M92-A-B
Game: In the Hunt / 海底大战争
Board marking: OSC 004170B1


There is a 4-pin connector labeled CN6 near the JAMMA connector.


From what I have found, CN6 appears to be related to the stereo audio / second speaker output, but I would like to confirm this from someone who has the original Irem wiring documentation or has experience with the M92 hardware.


My questions:​


  1. What exactly is CN6 used for?
  2. Is CN6 the output for the second speaker / stereo channel?
  3. What is the pinout of all four pins on CN6?
  4. Which pins are audio + / audio −, and are any of the pins GND or unused?
  5. How is CN6 connected in the original Irem arcade cabinet?
  6. If I want to use the M92 PCB at home, what is the correct way to obtain stereo audio from the JAMMA connector + CN6?
  7. Is CN6 a speaker-level output from the amplifier, or is it a line-level audio output?
  8. Can I connect CN6 directly to an amplifier / powered speakers, or do I need an attenuator or other circuit first?

I am particularly interested in the original factory wiring, rather than a modified/homebrew solution.


If anyone has the original Irem M92 wiring diagram, operator's manual, service manual, or a photo of the original cabinet wiring, I would really appreciate it.


I would also appreciate a photo or diagram showing the CN6 pin numbering and corresponding signals.


Thanks in advance!
ScreenShot_2026-08-08_144408_993.jpg
Click to expand...
Apologies for off-topic..
But did you make that acrylic case? Or where you got it from?
 
Astro X said:
surprisingly,
its really stereo - at least to my ears.........:saint:

btw:
are schematics for M92 available.....?
Click to expand...
Could you teach me how to connect CN6 to RCA? How to distinguish the L and R audio channels? I want to hook it up to my active speakers. The JAMMA audio from this arcade board is way too loud!
 
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