Need Help Monitor B+ is High

[Hooligan93]

Hi everyone,

Made some progress with my 14" sega Nanao MC-2000-S (MC-1400-S?). My voltages are high and even with my B+ adjustment turned all the way down it is still too high at 116VDC.

From the Iso Trans 110 Vac (marked 100vac on terminal)
Into board 110VAC
after first Inductor 110Vac
after Bridge rectifier 142Vdc ( schematics says 128Vdc )
at the Voltage Regulator  116Vdc with B+turned all the way down. (schematics says 105Vdc)

This is causing instability in my Vertical deflection about 1" on the very top of the screen. When I cool the Vertical output transister the screen almost returns to normal.
I have checked all resistors and diodes and have found no problems.


Any help please

[Hooligan93]

Finally got this monitor done. High B+ solved by itself. I may have wiped the B+ pot while adjusting up and down although i did intentionally wipe it when i was first having problems with B+ voltage.

Also I had vertical deflection foldover for the top one inch. Adding a 10 uf ceramic cap to Q402 across the Emitter and collector.

Picture is now almost perfect just have some color adjustments to do.

[John's Arcade]

Good job!

[Kopey]

Congrats on fixing your monitor!  Any chance your chassis looks like mine from my Monaco GP cockpit?  I am really trying to figure out what Nanao model it is.  I've emailed a few people that have the same chassis in their games but have yet to receive a reply from anyone.  ; (
 

http://digitalorange.ca/arcade/monacogp/IMG_5407.jpg

[Hooligan93]

Your chassis is completely different chassis and neck board. Search for Jomac on KLOV and Aussie Arcade. He is suppose to be the Sega/Nanao guru. I am noticing little Mitsubishi symbols on your neck board and chassis. Only Mitsubishi logo i had was on the tube label.

What is your monitor doing that you need to fix?

Take a look at this it may help.

http://www.jomac.net.au/services/monitors/

[Kopey]

Thanks.  I checked out that site but no match.  I will try sending him a message and see what he has to say.  Oh, it appears I have a vertical collapse going on.  I am going to try reflowing all the solder joints that look suspect and see if that fixes the problem first.  The voltages seem fine.  Thanks for the help!