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Hatsune Mike

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I did a writeup on a few things you can do to get the most out of your MS9, including

  • Placing a negative voltage on G1 like the MS8 for improved sharpness, and
  • Modifying the chassis to run at 31KHz for Naomi, etc.
http://mikejmoffitt.com/pages/ms9-hax/

Stay sharp!

ms9-donpachi.JPG


ms9-31k-cvs2-timer.jpg
 

Softdrink

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dewmansnk

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What a fantastic writeup! Thank you for sharing this valuable research.
 

IPD

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Thank you for doing this - very useful info indeed!
 

nem

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That sharpness mod really excites me. That's definitely something the MS8 has over the MS9. I'm working on a Daytona 2 twin cab with two MS9s. It's just sad what a blurry mess it is in 24khz. I rejuved the guns hoping I would get a stronger, more focused beam out of them, but nope.

Do you think a MS8 could be hacked to run 31khz too, @Hatsune Mike? Seeing 31khz on the -25 or the -26 would be pretty neat. I have tons of them. I could mod a few and I wouldn't mind sacrificing compatibility with 15khz.
 

West

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Sick write up! Would love to do these mods someday. Thanks for putting this together
 

IPD

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I've got one Nanao MS9-29 chassis without a tube, but I'm not sure which model variant it is. There are no labels anywhere. Are there other ways to identify which model it is? Maybe this is something worth documenting.

For example, I've noticed that the mainboard and the remoteboard both have a PCB ID, 05A00675C1. The neckboard has 05B00950C1. Based on some Google searching and a few arcade forum threads my guess is that this is a MS9-29A chassis. But it's just a guess.
 

opt2not

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@Hatsune Mike this write-up is gold to MS9 owners!

though the 31khz mod has too many caveats for me to bare, but the G1 voltage mod is hot-hot-heat! I’d be happy enough to do this for 15khz content.

thanks for this outstanding R&D!
 

Nebula

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Awesome work @Hatsune Mike . I will definitely give it a try using a spare MS9-29 I have.

Just for curious, regarding the Grid 1 voltage, you used the same value (~65V DC) as it's used in the MS8. I assume that it could has a window-range of proper values, but in some BK-precision rejuvenator manual, the A68KJU96X tube is marked to use 50V in the G1, while in some other tube models it advices to use 70V or 100V:

https://www.mouser.com/datasheet/2/43/CRT_datasheet-180889.pdf

Also in this site:
http://tubular.atomized.org/#s/xref:A68KJU96X

Is it safe to say that 65V would be a proper value to use in our beloved A68KJU96X tubes?


Anyway, we could assume if that is factory-used in MS8 with the same tube, that responds the question... ^^
 

brad808

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Awesome work @Hatsune Mike . I will definitely give it a try using a spare MS9-29 I have.

Just for curious, regarding the Grid 1 voltage, you used the same value (~65V DC) as it's used in the MS8. I assume that it could has a window-range of proper values, but in some BK-precision rejuvenator manual, the A68KJU96X tube is marked to use 50V in the G1, while in some other tube models it advices to use 70V or 100V:

https://www.mouser.com/datasheet/2/43/CRT_datasheet-180889.pdf

Also in this site:
http://tubular.atomized.org/#s/xref:A68KJU96X

Is it safe to say that 65V would be a proper value to use in our beloved A68KJU96X tubes?


Anyway, we could assume if that is factory-used in MS8 with the same tube, that responds the question... ^^
That is due to limitation of BK analyzers having fixed point "good" value on current meter and trying to find best area to test in for their meter.

First you read this...you start at "CRT Bias Range and Cutoff Test" : http://nestreble.ca/Sencore/SencoreNews185 - CR7000.pdf


Take this example now a67-510x tube:

BK setup information g1 50v:
Capture.PNG


Now let look at spec from manufacture:
Capture2.PNG


Now let look at cutoff chart:
Capture3.PNG


Now you see test information with CR7000 (operate on sliding scale emission) test at g1 132v
Capture4.PNG



Hopefully this help you
 

AMS

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Awsome to have so many smart people on this forum! Everyday there is something new and exciting :thumbsup:
 

BuddyC

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Sooooo... Would it be possible for any of you awesome CRT gurus to make a “How to place a negative voltage on G1 for dummies“? With pictures and parts to order so I don’t fuck up my only MS9?
Would donate some cash for your trouble <3
 

Hackcell

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Sooooo... Would it be possible for any of you awesome CRT gurus to make a “How to place a negative voltage on G1 for dummies“? With pictures and parts to order so I don’t fuck up my only MS9?
Would donate some cash for your trouble <3
PLEASE PLEASE PLEASE PLEASE :)
 

Nebula

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That is due to limitation of BK analyzers having fixed point "good" value on current meter and trying to find best area to test in for their meter.

First you read this...you start at "CRT Bias Range and Cutoff Test" : http://nestreble.ca/Sencore/SencoreNews185 - CR7000.pdf


Take this example now a67-510x tube:

BK setup information g1 50v:
Capture.PNG


Now let look at spec from manufacture:
Capture2.PNG


Now let look at cutoff chart:
Capture3.PNG


Now you see test information with CR7000 (operate on sliding scale emission) test at g1 132v
Capture4.PNG



Hopefully this help you

thanks! Now it’s fairly clear.

that 50V value is not more than a “placeholder” value for the BK analyzer to produce the current in a proper magnitude that it could be measured by it and check if it’s in the good area regarding G1 and G2 voltajes applied.

understood.

Can’t wait to test it when I have some free time.
 
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