[Solved]Nanao MS2930 - Blue screen shuts down

[JSN_]

Hello,

I’ve got a 2930 in a blast city cab. It was working before but then I cleaned everything and now i have a blue screen that will just shut down after a few minutes.

It is out of the cab right now so I have access to the pots. Just as a sanity check… the monitor only connects via the 3 inputs in the front right?

I will admit that I sprayed the pots on the front control panel with deoxit… thought it would help

 

[Metal Slug]

Hmmmm, it looks like there may be an image on the screen? Is there a MiSTer interface there? Or is it an all Blue image with screen burn and no signal going to it?

If it is receiving a signal, but the image is blue, check the RGB video connections. The signal travels from the Jamma loom through the front connectors on the frame to a connector on the rear left of the chassis. If you cant find a problem there, try tapping on the neck board or chassis with something non-conductive like a pencil to see if the colors flicker on/off, if they do you have dry solder joints and you'll need to re-flow some with fresh solder.

 

[JSN_]

Hmmmm, it looks like there may be an image on the screen? Is there a MiSTer interface there? Or is it an all Blue image with screen burn and no signal going to it?

If it is receiving a signal, but the image is blue, check the RGB video connections. The signal travels from the Jamma loom through the front connectors on the frame to a connector on the rear left of the chassis. If you cant find a problem there, try tapping on the neck board or chassis with something non-conductive like a pencil to see if the colors flicker on/off, if they do you have dry solder joints and you'll need to re-flow some with fresh solder.

It is a mister in there!! I had it working when i first got the cab. There’s also some heavy “Columns” burn in but its ok.

Based on my research I am seeing that neckboard solder joints are probably the issue.

My only problem is… how do I remove the neckboard? Lots of wires seem permanently attached … or just solder while it’s attached?

 

[rewrite]

My only problem is… how do I remove the neckboard? Lots of wires seem permanently attached … or just solder while it’s attached?

Some are permanently attached, some aren't.

Make sure you remove the one that goes to the tube (and remember to put it back when you're done, it's on a little post). After that, just wiggle it backwards and it'll come out. It'll still be attached to the chassis at that point, but it should be more than enough to see how your neckboard's soldering is looking.

 

[JSN_]

Some are permanently attached, some aren't.

Make sure you remove the one that goes to the tube (and remember to put it back when you're done, it's on a little post). After that, just wiggle it backwards and it'll come out. It'll still be attached to the chassis at that point, but it should be more than enough to see how your neckboard's soldering is looking.

Oh yea. I have no issue getting the neckboard off the tube. It’s just getting the neckboard off the main chassis itself.

 

[rewrite]

Oh yea. I have no issue getting the neckboard off the tube. It’s just getting the neckboard off the main chassis itself.

Not worth the effort at all. Just pull the whole chassis out of the monitor if you really need it removed.

 

[GeekMan1222]

theres really no need to remove the neckboard from the entire chassis board unless you are swapping the neck or something.
A number of wires/pin connections would be soldered directly like the G1 and Focus wires possibly a few others for stuff like color/video signals.
The focus wire will be hidden under a plastic door on the neck socket.

If you suspect something is wrong with the neck though you should investigate the solder joints and possibly related components and reflow where needed.

Parting the neck board from the chassis seems like extra work unless its something you absolutely have to do like a swap or something.

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There maybe two different issues happening here or they are some how related. In general having a single solid color screen indicates a loss of a color signal or worse case guns (but having 2 guns magically going out at one time seems highly unlikely.)

- Try using a different PCB
Verify and reseat the entire RGB wiring path.
- Reseat and check the remote board (make sure the pots for RGB contrast and brightness are working or test okay and are not damaged)
- Jamma Harness and RGB output to the monitor off the distribution board thing near the access door.
- Connections at the monitor frame.
Take close attention to the green and blue pins inside the plastic housings and or the condition of the wires. I have personally seen once where a single color pin became loose and falling out of the connector on the CRT frame. You could also just jostle all these cables while the cab is running and see if the colors pop in and out.
- Reseat the RGB wires on the chassis and neck board, reseat the neck
- Check the Color cutoff pots on the chassis as well as the sub contrast
- Test the CRT gun emissions
- Test the Video Amp
- Test the Color drive transistors
- Check for bad components board level related to video colors

This still wouldnt explain why the chassis is shutting off??

Maybe something is being overdriven here which maybe more likely.
- Test the pots for contrast sub contrast and brightness and colors
- confirm the B+ and Anode Voltages (you need to know how to do this and have special probe to check the Anode its dangerous voltages)

I have not dealt with it alot but I have seen once where a Nanao monitor I got from some operators cranked the cuttoffs gains contrasts and ABL to the absolute max and it was causing the chassis to shut down. So its worth sanity checking these parts for their setting and if they are failing or something.

Thats all I really got to say you just have to dig into this rabbit hole deeper to get more clues or info

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Edit:
Another thing that might be useful to check is can you even adjust your contrast or blue drive? If the blue drive pot or cut off pot is bad it could be causing the entire screen to just show blue lol?

Theres so many different things that COULD be happening your just gonna have to keep messing with it until you find something else hopefully that seems off or weird.

 

[JSN_]

Thanks @GeekMan1222

I noticed that the board will stay on until i turn up the brightness on remote board or screen pot on the flyback. Then the monitor just shuts down.

I think my first step will be to reflow the solder joints in the neckboard as called out by a few.

If that doesn’t work, I’ll take a look at the IO board inside the cab.

Funny thing is I was able to play 1943 on the mister in all blue

 

[JSN_]

Took off the neck board. Some of the pins on the tube were slightly bent and the plastic “key” was broken Is this catastrophic?

Regardless… how do i get the chassis itself out? Seems to be a lot of metal and plastic tabs, is that what’s holding it to its frame or are there screws?

 

[nem]

Is this catastrophic?

No, it's just a key. Just be mindful of the orientation when you put the neck board back on.

I think it's more likely the blue is being overdriven, and not that red or green are missing.

Make sure to wiggle the connectors on the front of the monitor before doing anything else. You need to do this with the monitor on. It's a common weak point in the Blast monitor.

If nothing changes, next step I would take is I would swap the color transistors on the neck board. Make sure you swap blue with one of the other two (0 is red, 1 is green, 2 is blue).

It's also possible the tube is shorted.

 

[Metal Slug]

Regardless… how do i get the chassis itself out?

The chassis can be removed by removing a few screws on the bottom of the frame, the chassis will slide out attached to the metal tray. You remove the chassis from the tray to service it and gain access to the solder pads on the bottom by unscrewing the corners and possibly one center screw, and slide it from the plastic holder.

The color drive pots as others have mentioned could be something to look at too, does anything change when you turn them?

 

[JSN_]

The color drive pots as others have mentioned could be something to look at too, does anything change when you turn them?

I get some flickering and slight changes but it is still mostly blue.

There are 2 pots on the remote board that also do very little. B gain and R gain

 

[ekorz]

Is it just me or does it look like the connector is not seated completely in the above photo?

 

[JSN_]

Is it just me or does it look like the connector is not seated completely in the above photo?

I noticed that too after posting but this is an old pic. I can verify its seated properly now

 

[tiff_lee]

When you cleaned those pots did you adjust them at all? to 'work the insides' etc, this just seems to be escalating somewhat.
What started off as a working tube, to having a simple pot clean has resulted in the neckboard being removed. When I saw that mark on the tube neck at post #9 I was worried this was going to become another necked tube thread.

 

[ekorz]

When you cleaned those pots did you adjust them at all? to 'work the insides' etc, this just seems to be escalating somewhat.
What started off as a working tube, to having a simple pot clean has resulted in the neckboard being removed. When I saw that mark on the tube neck at post #9 I was worried this was going to become another necked tube thread.

Yeah i had that feeling too. Feels like something simple, like not something that requires completely disassembling everything. Like the jamma connector has a loose grip.

 

[JSN_]

When you cleaned those pots did you adjust them at all? to 'work the insides' etc, this just seems to be escalating somewhat.
What started off as a working tube, to having a simple pot clean has resulted in the neckboard being removed. When I saw that mark on the tube neck at post #9 I was worried this was going to become another necked tube thread.

i just sprayed the pots on the remote board and cleaned them like you said. Gave them a few turns etc. I didn’t spray the pots on the chassis but i did give it a simple green/ water rinse a few weeks ago. It has dried out completely. I’m going to post results of neckboard reflow soon

 

[rewrite]

I think it's more likely the blue is being overdriven, and not that red or green are missing.

Yeah, the fact you can see the Mister bits under the blue shows that to be the case.

Sounds like blue transistor failed open or a blue gain/bias pot isn't working any longer. I say run a multimeter against the pots and see if they actually work. That's the easiest first step aside from checking for loose connections.

I didn’t spray the pots on the chassis

Do these too, no reason not to. Spray into them, turn end to end 20-30 times just to be sure.

 

[tiff_lee]

i just sprayed the pots on the remote board and cleaned them like you said. Gave them a few turns etc. I didn’t spray the pots on the chassis but i did give it a simple green/ water rinse a few weeks ago. It has dried out completely. I’m going to post results of neckboard reflow soon

So after the water rinse it was working fine up until you did the pot clean? or were they done at the same time.

 

[JSN_]

So after the water rinse it was working fine up until you did the pot clean? or were they done at the same time.

No it was working fine before water rinse. Sorry for lack of steps. I’m remembering what I did as we talk through this