Hatsune Mike
Champion
In a bit I'm going to put together a really simple shopping list for populating the G1 section and enhance the guide with more pictures.
- Thread starter Hatsune Mike
- Start date
Wow incredible work, thanks for sharing! I love CRTs in arcade cabs, but fully admit to being a total thicko when it comes to the knowing how they work. Nevertheless I read this writeup from start to finish and was fascinated - very readable even for novice. Amazing to have so many seriously clever people on here sharing their knowledge in a generous and unpretentious way.
I have a twin Japanese Daytona 2 that I'm currently restoring that has MS9 monitors - one side has the stock (for Japan) Toshiba tube, whereas the other is a Hitachi. No doubt the Toshiba tube is superior and interesting to note that the curvature is also different. Lucky for me I have the correct version bezel for each tube, but I'd like to get a Toshiba tube in the other side at some point. There must be about half-a-dozen different bezels I've come across for Sega drivers to allow for the various monitors that have been installed in them over the years.
I have a twin Japanese Daytona 2 that I'm currently restoring that has MS9 monitors - one side has the stock (for Japan) Toshiba tube, whereas the other is a Hitachi. No doubt the Toshiba tube is superior and interesting to note that the curvature is also different. Lucky for me I have the correct version bezel for each tube, but I'd like to get a Toshiba tube in the other side at some point. There must be about half-a-dozen different bezels I've come across for Sega drivers to allow for the various monitors that have been installed in them over the years.
Does the bezel fit the Hitachi? I've only ever seen one bezel for the Astro and that's for the Tosh.
It definitely fits, it definitely has a miniscule gap more than the toshiba. I actually just though it was from age that the bezel may have bended a little more, especially since this cabinet was disassembled and re sprayed. It's negligible really. You can only tell because the astro is next to it.
In identifying the MS9 variants, is there a specific number or mark on the chassis that helps identify the variant on the chassis?
Typically if the chassis is paired with the tube you can identify it by the markings on the tube/frame, but I have several MS9 chassis with no tubes and I'd like to identify which MS9 variant they are.
Typically if the chassis is paired with the tube you can identify it by the markings on the tube/frame, but I have several MS9 chassis with no tubes and I'd like to identify which MS9 variant they are.
A while back @twistedsymphony and I went on a journey to find out what was hiding behind all these different MS9 chassis PCB versions. This was all based on googling chassis images. We came up with the following list:
- PCB-MAIN: 05A00675D1 (red C101, green wire over U550)
- PCB-MAIN: 05A00675C2 (red C101, green wire over U550)
- PCB-MAIN: 05A00675C1 (red C101, green wire over U550)
- PCB-MAIN: 05A00675A1 (red C101, black wire over U550)
- PCB-MAIN: 05A00585D1 (black C101)
rememberizer
Student
Is it possible to do this 31khz mod on an MS8?
I have the G1 mod in a number of MS9s now. It's a nice improvement in sharpness. Not huge or anything, but worth doing.
I also found out the MS8-26 has provisions for the same modification, but the flyback doesn't output a low enough voltage to make any difference
I also found out the MS8-26 has provisions for the same modification, but the flyback doesn't output a low enough voltage to make any difference
andynumbers
Professional
I have done the G1 mod to all of my MS9s. My general consensus is that it's not majorly beneficial if you are only running 15khz resolutions. You will get PVM-like scanlines right in your face. This may be uncomfortable to people that do not like the sharp scanline look.
HOWEVER, with that said, if you are running an MS9 in a 24khz game, such as a Sega racer or Densha De Go, the G1 mod look amazing and is highly recommended. You will get computer monitor level sharpness and you simply won't be able to go back.
The VGA mod is interesting, but there are caveats. Geometry will be compromised and you still have to amplify the video levels to TTL level, even though the 31khz standard is almost always consumer 0.7vpp level. If you are doing this mod so that you can go back and forth between 15 and 31khz often you shouldn't do the mod. Colors and major geometry adjustments are needed when changing between the two resolutions. My opinion is that you should only do this mod if you want to permanently change your MS9 into a 31khz only monitor. And at that point, just hunt down a 2932 or another 31khz only monitor instead of compromising a good working MS9.
HOWEVER, with that said, if you are running an MS9 in a 24khz game, such as a Sega racer or Densha De Go, the G1 mod look amazing and is highly recommended. You will get computer monitor level sharpness and you simply won't be able to go back.
The VGA mod is interesting, but there are caveats. Geometry will be compromised and you still have to amplify the video levels to TTL level, even though the 31khz standard is almost always consumer 0.7vpp level. If you are doing this mod so that you can go back and forth between 15 and 31khz often you shouldn't do the mod. Colors and major geometry adjustments are needed when changing between the two resolutions. My opinion is that you should only do this mod if you want to permanently change your MS9 into a 31khz only monitor. And at that point, just hunt down a 2932 or another 31khz only monitor instead of compromising a good working MS9.
I love the look of them sweet, sweet scanlines - was on the fence about doing this mod, but the sweet siren song of scanlines has seduced me.
andynumbers
Professional
If you're gonna do the mod, the diode I used was a BAV23C-7-F, but they seem to be OOS on Digikey and Mouser. There may be some on ebay still. Perhaps @Hatsune Mike can chime in with an alternative for D506? His guide doesn't specify a specific part number, so it may be difficult for some to source a compatible diode.
Ok, thank you all for your answers !
Regarding the diode, i'll try with P0102BL 5AA4 STMicroelectronics... i think
EDIT: don't use this diode, it's not the correct pinout...
(the G1 mod works [fine btw, tested for 50 hours+], but there's no protection if something goes wrong... as the diode doesn't guide the electrical flow on the "good side".)
Use these instead:
https://www.mouser.fr/ProductDetail/771-BAT54C235
https://www.mouser.fr/ProductDetail...nts-MCC/BAS21C-TP?qs=KFo7JewZbUHDvl7XOTRtIA==
EDIT: don't use this diode, it's not the correct pinout...
(the G1 mod works [fine btw, tested for 50 hours+], but there's no protection if something goes wrong... as the diode doesn't guide the electrical flow on the "good side".)
Use these instead:
https://www.mouser.fr/ProductDetail/771-BAT54C235
https://www.mouser.fr/ProductDetail...nts-MCC/BAS21C-TP?qs=KFo7JewZbUHDvl7XOTRtIA==
Last edited:
I used this one
https://www.digikey.com/en/products/detail/diodes-incorporated/MMBD7000HC-7-F/2179584
I have had my monitors on for hundreds of hours. Should be fine.
https://www.digikey.com/en/products/detail/diodes-incorporated/MMBD7000HC-7-F/2179584
I have had my monitors on for hundreds of hours. Should be fine.
Softdrink
Professional
I've been running the 31k mod on an auto-switching MS9 for quite a while, and while I agree that it's not a perfect experience, it's not nearly what you've described here from what I've seen. I've not had any color issues when changing between resolutions - only a minor tweak to Contrast is needed on my setup (though as noted in Mike's guide, overall brightness is reduced at 31k).
I won't sugarcoat it though, it is finicky, and geometry is a big challenge, especially since depending on the input signal there will be varying amounts of 'edge rollover'. On my NAOMI I don't get any artifacts like that, but on a PC or Xbox 360 it's quite severe. Anyone considering the mod will need to be aware that it's going to have significant limitations with certain signals, and that there will be a large degree of variation between sources. It will not be perfect at 31kHz. Period.
I've found that calibrating the monitor fully for 15kHz (color and geometry optimized for this mode) and then only making the necessary tweaks to get 31 to display 'decently' is the right approach for my setup.
As for the VGA input level issue - I just use a JVS/JAMMA I/O to ingest the VGA signal; those are already designed to do the necessary level conversion.
Overall, I would disagree with your conclusion - switching between 15 and 31 is totally fine with the mod from my experience; my 15k performance is great and 31k is very tolerable with just Size/Position and Contrast adjustments needed when swapping (all of which I'd probably need to do anyways when changing boards). As long as you're willing to compromise on perfect geometry and perfect compatibility with all sources, it's more than serviceable.
In my case, there are absolutely no 24kHz games that I currently own or plan to own, whereas there are quite a few 31k games that I enjoy, so it was essentially a "free" upgrade from my perspective (and I have a spare chassis in storage if I ever want to play 24kHz stuff that I can swap back in easily enough).
With all that said - now that I have my Blast to work with I've been using that for all my 31kHz content, since using a monitor designed to support the resolution is a significantly better experience.
I’ve only done the g1 focus mod. Which is fantastic! The sharpness is noticeable.
Not going to touch the 31khz mod. It looks interesting, but that’s too much of a change that sounds more prone to issues for it’s own good. I use downscalers to get 24khz from 31, and the image looks great. Good enough for me.
Not going to touch the 31khz mod. It looks interesting, but that’s too much of a change that sounds more prone to issues for it’s own good. I use downscalers to get 24khz from 31, and the image looks great. Good enough for me.
