Does anyone know by chance if the MT3 series reader is the same as any other game? From the pictures does not look like it as it looks more similar to newer ID but is still magnetic.
Cards from ID1-3 and DOC aren't 100% compatible with WMMT. These cards don't allow for erasing the thermal printing whereas WMMT's cards do. So if one of these cards gets used, you end up with a very smeared mess as it tries to erase and reprint. The data does save correctly, though. At least that was my experience in the rightmost reader in your pic.
I will post here for anyone that needs this information:
MT3/3DX/3DX+ uses a SANWA CR-S31R-10HS3 Card Reader/Writer.
On my MT3 cabinet, I am able to use ID1/2/3 cards in this reader to play Maximum Tune 1/2/3/3DX+ and it works fine. The cards used are the same type of cards as Derby Owners/Max Tune 1/2/3/3DX/3DX+, Mario Kart GP1/GP2 and F-Zero.
If you use this card reader for games other than Maximum Tune 1/2/3/3DX/3DX+ you have to adjust the DIPSW setting to match the communication set for the specified game.
SANWA CR-S31R-10HS3 Card Reader/Writer PCB:
There is a similar card reader/writer with model: CRP-1231LR-10NAB that looks to be off of a Maximum Tune 1/2 cabinet in the US.
The Card Reader/Writer for Initial D Arcade Stage 4/5/6/7/8: CR-2PR-10H-SG only looks similar in design and layout but not in functionality. This card reader uses a different card altogether from the other two.
Both the CR-S31R-10HS3 and CR-2PR-10H-SG have a slot for a Compact Flash card. I don't know too much about either one but sources online lead me to believe this is the gateway to updating the firmware and other such functionality whereas the CRP-1231LR-10NAB has a ROM chip(?)
On the CR-S31R-10HS3 Card Reader/Writer, there is a special set of DIPSW values that are set for mechanism and board testing.
For your reference: