Rear controls on FMT-DP531 CRT monitor

[UnbornApple]

Hello, I just got a FMT-DP531 CRT from Yahoo Auctions Japan. I don't have an FM Towns computer (yet!), so I was planning on using it with other consoles/computers for now. It came with a DB15 to JP21 cable, so now I'm waiting on a JP21 to SCART adapter.

I've only confirmed it powers on, the power LED lights up, and the high voltage/degausing coil makes its characteristic sound. I don't see anything even if I turn the brightness all the way up, so I'm hoping this is one of those displays that only does anything if there's an active input connected.

On the front there's H-POS, Brightness, and Contrast controls. On the rear there are four recessed pots with Japanese labels, I'm curious what these do. The right three seem to be related somehow. I thought maybe red/green/blue adjustments?

[UnbornApple]

I managed to draw some of the kanji into some translation sites and it looks like they're all for vertical hold/geometry controls.

[incrediblehark]

Glad you got it sorted out! Here's some screenshots I did of the FMT-DP531 running other games in RGB (didnt have a working Towns at the time). https://imgur.com/gallery/CZBn7nA
I have a scart to db15 towns connector with audio breakout I use for it, works well.

[UnbornApple]

I found your gallery by searching Google when I first got the monitor, it was very handy.

The monitor is really great for 240p content. 480p looks great, but it has a lot of underscan. There doesn't seem to be any potentiometers to control h-size, which I guess is normal for displays this size? I haven't been able to try any 24khz content yet. I was going to use the X68000 core on the MiSTer, but I can't figure out a way to hit the HELP key most games require to switch modes.

Keeping this FM Towns related, I did just win an auction for an FM Towns II, so I'm looking forward to that!

[famiac]

Here are my nonsensical repair notes for the DP535. maybe some of it applies to the 531. i can't seem to remember if one of these adjusts the H-size. i will take a look.

FMT-DP535
——
Neck board pots:
Red Cut Off
Green Cut Off
Blue Cut Off
Screen
Focus
Conv.VR (Convergence Pot)
——
Input board pots:
S. cont (sub contrast)
S. Brt 2 (sub brightness)
R. drive
G. drive
VR205 (yellow while others are blue) labelled JØ104 while others are JØ203
——
Main Board Pots:
V. Hold
V. Size 15k
V. Size 24k
V. Size 31k
V. Posi 24k
V. Posi 31k
V. Posi Main
PCC Amp 31k
PCC Amp 24k
PCC Amp 15k
PCC Phase
H Posi 15k
H Posi 24k
H Posi 31k
——
Unknown pots. Color yellow. Labelled for scan rate
VR454 - 15k
VR455 - 24k
VR456 - 31k
V. Lin VR410
VR7451 unlabelled
——
Two pots on Flyback
Focus and screen
——
Top right corner
Pull Wide
OVP
——

[UnbornApple]

That sounds pretty much the same as what I saw in the 531. I don't remember seeing a convergence pot on the neckboard but I may have missed it.