19" Nanao MC-2000-S diagnosis

[mametester]

My 19" Nanao MC-2000-S is not displaying anything currently. I do see a neck glow when turned on though. Any ideas what could be wrong? Here are some pics of the main and neck board:

[grantspain]

what happens if you turn the screen volts up a wee bit
neck glow normally means its running and if you switch it off and see a flash from the screen then it is almost certainly running

[Ken Layton]

And this is after recapping it?

[mametester]

And this is after recapping it?

I have a cap kit from Bob Roberts but haven't capped it just yet.

[grantspain]

caps can cause very strange problems when they go leaky,a good example is the 10uf 250v cap on the g2 of the ms8,ms9 nanao chassis neck card-this causes all sorts of brightness issues

[mametester]

caps can cause very strange problems when they go leaky,a good example is the 10uf 250v cap on the g2 of the ms8,ms9 nanao chassis neck card-this causes all sorts of brightness issues

Finished recapping it and found three oddities:

1) C524 (47uf 160v) had leaked (and now replaced along with all other caps included in Bob Roberts kit).
2) C501 (10uf 25v) was never soldered onto the board originally. Do I need this capacitor?
3) C905 (680uf 180v) also looks like it is bad, but is not included in the Bob Roberts kit (please see photos below).

[Ken Layton]

From your picture I could not see any problem with c905. Did you unsolder it and test it with your capacitor meter/analyzer?

That one does not normally go bad so is not included in the kits. Did you replace cap c523? It is located inside the cage around the flyback and is often hard to see/find?

Have you reassembled your monitor and powered it up yet? How did it look?

[mametester]

From your picture I could not see any problem with c905. Did you unsolder it and test it with your capacitor meter/analyzer?

That one does not normally go bad so is not included in the kits. Did you replace cap c523? It is located inside the cage around the flyback and is often hard to see/find?

Have you reassembled your monitor and powered it up yet? How did it look?

Yes, I found two capacitors hiding inside the cage around the flyback and recapped them.

I haven't reassembled the monitor just yet because of the following two unknowns still:

1) C501 (10uf 25v) was never soldered onto the board originally. Do I need this capacitor? (Look at the 2nd photo in my first post, you can see C501 was missing in the lower left corner near sw2.) But the cap kit included a cap for C501.

2) C905 (680uf 180v) also looks like it is bad, but is not included in the Bob Roberts kit (please look at the lower left side of the capacitor there is some brown crud same as what I found on the bottom of my other blown cap C524).

[Ken Layton]

1. My own personal capkit list for this chassis does NOT have a C501 in it. This comes from my own experiences working on this model.

2. That's just dried glue. It was originally put there to keep such a large capacitor from breaking loose from the board during shipment across the world from the monitor manufacturer. That capacitor is probably 99.9% good.

[mametester]

what happens if you turn the screen volts up a wee bit
neck glow normally means its running and if you switch it off and see a flash from the screen then it is almost certainly running

Finished the recap and finally hooked it up. After turning up the volts up a wee bit I got some illumination. I see vertical  jagged lines and can now see the extensive burn in of this Zaxxon tube, but there is  no real color in the picture and the brightness pot didn't seem to have any effect. Any ideas?

[Ken Layton]

Looks like it isn't getting a good (or any) signal from the gameboard.

[Kevin Mullins]

After turning up the volts up a wee bit I got some illumination. I see vertical  jagged lines and can now see the extensive burn in of this Zaxxon tube, but there is  no real color in the picture and the brightness pot didn't seem to have any effect. Any ideas?

Well, that's a good sign for the monitor anyways. The lines will go away once you turn the SCREEN voltage back down once you get a picture and have to readjust everything. The brightness pot is probably not making any effect because the SCREEN voltage is turned way up right now. So there again, if you turn it back down you should be able to adjust the brightness and notice a change.

But.... like Ken said, there doesn't appear to be any actual game input going to the monitor.
What game is in this cab? (mentioned Zaxxon burn)

Can you coin it up and hear any games sounds and play it "blind"? (no picture)

[mametester]

Well, that's a good sign for the monitor anyways. The lines will go away once you turn the SCREEN voltage back down once you get a picture and have to readjust everything. The brightness pot is probably not making any effect because the SCREEN voltage is turned way up right now. So there again, if you turn it back down you should be able to adjust the brightness and notice a change.

That's good to hear. I will turn down the screen volts and see if I can get the brightness back to adjustable.

But.... like Ken said, there doesn't appear to be any actual game input going to the monitor.

What game is in this cab? (mentioned Zaxxon burn)

Yes, there's a Zaxxon pcb in this Zaxxon cab and it's all original except for the new caps I just soldered onto the monitor chasis.

Can you coin it up and hear any games sounds and play it "blind"? (no picture)

Yes, I can coin it up and hear the game playing blind. What should be my next step?

[grantspain]

your next step is to trace the video signal cable and make sure its on the correct connector

[mametester]

Just wanted to say thanks to grantspain, ken, kevin and everyone else who's even just looked at my post. It's very much appreciated.

[Kevin Mullins]

Is that a good sign then ??

And as always.... we're glad to help if we can.
(heck, we all learn something new quite often from it)

[mametester]

This is my first time trying to fix electronics of this magnitude so please bear with me.

Do I just disconnect the video signal cable from the chasis and then power up? Do I need to disconnect power to the chasis for safety? Also, in general when adjusting a monitor what are the parts that I really don't want to touch while it's powered?

[mametester]

Looks like it isn't getting a good (or any) signal from the gameboard.

What kind of voltage(s) should I find on the R,G,B,GND,SYNC lines? And they should be DC right?

[grantspain]

r,g,b should read anything from 1v to 3v

[mametester]

r,g,b should read anything from 1v to 3v

From the video out cable I found r & g to be in the range of [0.1, 0.3] volts and b to be in the range of [0.1, 0.7] volts. All of which are below the range of [1.0 - 3.0] volts.

[grantspain]

would be good if you could supply pics of where your video cable attaches at both the monitor side and the game board side

[Ken Layton]

This document may help:

http://arcarc.xmission.com/PDF_Monitors/Sega_MC-2000-S_Flowcharts.pdf

[mametester]

would be good if you could supply pics of where your video cable attaches at both the monitor side and the game board side

I hope this helps:

P1100847.JPG shows the plug that I used to test the r,g,b,grnd,sync voltages.

P1100848.JPG shows the other end of the plug that attaches at the monitor side.

P1100849.JPG and P1100850.JPG are shots of the monitor from the bottom and back respectively.

P1100851.JPG and P1100852.JPG shows the pcb connection (it's hard to see the video cables, but they do break off upwards to the monitor.

[mametester]

Measured the voltages going into my monitor:
Red = 0.4v
Green = 0.4v
Blue = 0.7v
Sync = 4.4v

Got the same values coming off the game pcb also. Aren't those values kinda low?