Nanao MS8-29 (Sega Astro City) Calibration Help

[retrogamer593]

Hi guys. I finally managed to power up my astro city with a jpac. First time sitting in front of an 15khz arcade screen and atm I'm not very fond of the picture.
It is simply to powerful...my eyes hurt when sitting 5 minutes in front of this thing, cause it is as bright as a standard tv. Is it supposed to be like that ?
Thing is I only have rgb gain and a brightnes potentiometer on the screen control board....turning the brightness potentiometer down, makes me loose all my contrast. I only have blacks, no greys at lower brightness.
Another thing I've tried is using the windows color calibration and turning gamma all the way up then turning the brightness nob down. It helped a bit...put picture quality is a bit meh..
Tried over an hour now...

Any tips , and I wonder if its the same with a MS9, is this thing also bright like the sun ^^?

[grantspain]

you also have colour cut offs on the main chassis, on this particular chassis the gains and cut offs affect each other so calibration can be painstaking

[retrogamer593]

I found a japanese manual on the arcadeotaku wiki...so I assume that the contrast pot is directly on the chassis with the other missing controls
So how do I access the pots on the chassis, do I have to take off the back of my astro

[grantspain]

ms8-29 do not have contrast control, contrast is achieved through adjustment of cut offs and gains

[retrogamer593]

Thanks for your answers
I did some calibration using this guide
http://wiki.arcadeotaku.com/w/How_to_Co ... Brightness
I couldn't turn the rgb cut-off pots any more further after adjusting the gain values, there was still a bit of room but not enough to bring the last 3 shades or so back up. Brightness knob was in the middle.
For Safety, I turned the cut-off-pots back a bit, since I don't know if its bad for the chassi/screen if they are turned fully.

I guess I should have turned the screen pot before that, but I still haven't found out where the neckboard is located.
How can I access it?
At least I found out my tube.
Its a Toshiba A68KJU96X.

[grantspain]

there are no adjustments on the neck board

screen volts is the bottom adjustment on the flyback

[retrogamer593]

Many thx for your answers.
I finally discovered the pots on the flyback and did another calibration round...much better.
Thing is, the guide i linked above says to put everything down to 0
Brightness, R-G-B Gain&Cutoff.

I should display a grid and then I should go down with screen voltage until I don't see that grid anymore.
However, for this to work I would have to put the screen voltage extremely high, because with the brightness pot on 0 i wouldn't see anything.
I don't know how high I can go with the screen pot, out of fear that i could damage anything i put the brightness pot to 25% and adjusted the screen voltage to the value that the grid just dissapears.

Calibration succeeded, scanlines don't seem that aggressive anymore, and the screen itself is maybe a tad less brighter..colors also seem pretty spot on.
Would something have changed for the better if I would have adjusted the brightness pot to 0 before adjusting the screen pot?

Another thing...when a tube is kinda burned out..will there be a loss of contrast that would be compensated by adjusting the screen voltage to a higher level, which would wear out the tube even further, or am I completely wrong with this assumption ?

[grantspain]

screen volts should be nowhere near max

I setup by turning everything to 0 and then set cut offs to about 10-12,set brightness to about 12,screen volts up until a reasonable picture appears and then use gains to get depth-then fine tune everything