Rear controls on FMT-DP531 CRT monitor

Started by UnbornApple, January 10, 2023, 01:48:01 PM

Previous topic - Next topic


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?


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


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).
I have a scart to db15 towns connector with audio breakout I use for it, works well.


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!


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.

Neck board pots:
Red Cut Off
Green Cut Off
Blue Cut Off
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


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.