Nanao MS8-26SU Vertical Deflection Failure - Fixed

[modessitt]

Have a Nanao (Sega) MS8-26SU (Med-Res) in a kitted Cruis'n USA showing a horizontal line.  Installed a cap kit - still no vertical.  Replaced Q401 & Q402 (D1138 transistors) - still no vertical.  Touched up solder joints throughout the area - still no vertical.  Inspected for broken traces and did continuity checks - no problems found.  Any other ideas?

I can't find a schematic for this monitor so don't know all the parts that could cause this problem.  After reading posts about the MC-2000-S, I checked the two big white fusible resistors, even taking them out of circuit, and they seem to be fine.  I even checked the yoke resistance and get 1.1 from red to blue and 37.6 from yellow to brown (Mitsubishi tube).

Star Tech Journal supposedly has vertical failure resolutions posted in Issue 26, August, for this type of monitor, but I don't want to pay $20 to find out I should do what I've already done.  Anyone have a membership there that could check and e-mail me the info?

If anyone has any further ideas, a manual/schematic they could look through/email to me, or has fixed this type of problem on this monitor before,  your help would be greatly appreciated.

Thanks,
Modessitt

[Ken Layton]

Forum member Jomac in Australia is the resident Nanao expert and has the cure for your monitor problem. Visit his site (www.jomac.net.au/mon.htm) or email him.

Remember that here in the USA, Nanao manuals/schematics/parts are impossible to find.

[modessitt]

Thanks, Ken.  Will do.

While I was out on a service call, my boss tried to hook it up to see if he could figure it out, tried to attach the yoke connector by feel, and accidentally connected the yoke connecter to the "Low" connecter right next to it, powered it up and blew the fuse.  It now blows the fuse whenever powered up, so now I have to figure out what shorted out.  (Sigh)

I'll e-mail Jomac and see if he can point me in a direction.

[Rickn]

If you remind me on Monday morning -e-mail me Sunday night, I will check. I may still have a schematic for the MS8 at the factory.

I built both the MS8 and MS9 for Eizo Nanao.

It's been way too long since I worked on one but hopefully I willbe able to help.

Rick Nieman
President Nieman Video Displays
519-621-1722 Toll free 1-866-747-4002
Rick@niemandisplays.com

[modessitt]

Just wanted to update in case someone else gets a similar problem with this monitor and needs help.  I did get hold of Jomac and he sent the following response (imagine an Australian accent):

"Real shame it is blowing fuses now as it can get complicated .
 
the vertical problem is a simple one.
 
Replace C433 ( 10uf 50v ) and R433 ( 2.2K 1/4w ) , if still not deflection replace R436 ( 15K 1/4w )
 
 
For the blowing fuses , I am assuming it is the 1 amp fuse that is blowing , so first you will need to check the Horizontal drive transistor , its mounted externally on the heat sink with 3 wires going to it ( 2SD1880 ) if you are lucky only this will be blown but before you power it up check for a shorted transistor Q901 in the power supply section , if this is shorted it will cause a lot of other problems.
 
Let me know how you get on , and keep in mind I get these chassis everyday from the all over the world so sending it here for repair is still an option if you get stuck ."

Well, there's no way my boss is going to want me shipping a chassis all the way to Australia, so I got busy.

As far as the short goes, both the Horizontal Output Transistor (D1880) and Q901 (C3306) in the PS section were shorted out.  Of course, C3306 (NTE2308) wasn't available locally so I had to order it.  In the meantime, I went back to the vertical deflection problem.  As I had already replaced C433 when re-capping, I went to the resistors.  I like to test resistors out of circuit, and started to remove R433 when it crumbled into pieces.  AHA!  Thankfully Jomac had included the correct value as it was impossible to read after that.  Replaced the resistor and checked the other which was fine.  After a few days, my transistors came in.  Reinstalled them, taking Jomac's advice on checking the other small transistors in the power circuit for any other shorts.  After finding none, I replaced the fuse, installed the chassis, and powered up.

SUCCESS!  Monitor did not blow the fuse and vertical deflection was back!

Hopefully, this will serve as a warning to all techs not to plug in anything involving high voltage by feel.  If you can't see it's right, assume it's not.

Thanks to Ken for pointing me to the right person, Jomac for giving the important info, and Rick for offering the paperwork.  I'd be glad to take it anyway just to have it if you still have it available, Rick

Hope this helps anyone else who may have a similar problem with this chassis.  Later.

[PaTrYcK]

Hi, i have the same problem on my monitor nanao ms8-26...
I had a single horizontal line in the center (with small flicker), i have change C433-C437-Q401-Q402-R433-R436 (only R433 was broken) but the problem is not solved

The image now is only open at the top (for a moment I see the picture), but then immediately collapses, then reopen it, but collapses on ......ecc...

Some idea for fix it?

Thanks!

[PaTrYcK]

Hi, i have fix it, the new q402 was broken, i change it now is ok!

[Ken Layton]

Updating this old thread. Here is the service manual and an 11 x 17 of the schematic in a zip file:

http://www.google.com/url?q=http%3A%2F%2Fwww.flippers.com%2Fpdfs%2FNanao_MS8-26SU.zip&sa=D&sntz=1&usg=AFQjCNEY11LS7wzrBoTShYUhBq4Fb0guQg

[Ken Layton]

Here is a picture of the silkscreened numbers on a MS8-26SU chassis.