Blast City monitor identification and questions

[Arcade-Projects]

A buddy of mine is really new to the hobby and I'm trying to help him out. He recently got 2 Blast City cabs. Tested both out last night and are in working order for the most part. However they are not exactly equal in terms of what came installed inside each cabinet.

One of them has a Sanwa monitor. From what I can tell in the picture I took, the model number is 29E31-73. The chassis came equipped with an VGA cable and we were able to use that to successfully test 31khz video via Dreamcast. Looks fantastic actually. However we were unsuccessful in getting 15khz Jamma video to work on this machine. We're testing with CPS2 and I can confirm the board powers up, stereo audio works via RCA jacks from the A board, and the game functions, able to play blind. I searched around a bit and was not able to find information about this monitor based on that exact model number. I did find info about the 29e31s and that one apparently operates at 31khz only. Can anyone confirm what we're working with for this monitor? Is this one also only 31khz or is there a way to force a change to support other modes? I didn't see anything in the monitor remote board aside from the pots to adjust the normal settings, no dip switches or anything like that. Likewise on the chassis but I didn't dig around fully out there yet.

The other cab has a Toshiba monitor and that fired up in 15khz without issue. I tried 31khz on that one via Dreamcast and I get an image but the video rolls. Seems like it's not synced? The owner is mainly interested in getting 15khz video on these cabinets but it would be nice to solve this issue as well.

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