Nanao 2931 Monitor woes

[thieslo]

Ok, my blast city monitor died a few weeks ago. I figured it was my chassis so I purchased a new (to me) chassis working and it arrived.

It is a Rodotron chassis, well I seemed to have plugged everything up, but I am still not getting any picture.

I have degauss plugged into the far edge, the single ground connector connected to the neckboard, the connections going frmo the monitor frame into the side (for RGB, power), and the VGA cable going from the neckboard to the side PCB (with the power connector).

I also have the Horizontal and Vertcal sync connected in the middle of the chassis board.

As far as I can see everything is hooked up properly, however when I power it on all I get is a loud, high pitched squeel, and some fun fireworks (pretty constant) display on the neck of the tube. Absolutely no picture on the screen. The screen quit working while stationary, so I don't believe it to be a case of necking the tube or anything (also doubt I would get the firework on it).

If I disconnect the Horizontal and vertical syncs from the chassis board I get no neck activity and a very faint, almost impercetible squeel.

While it is on, I smell some fun smells, not sure if it is electrical components toasting or the dust being burned off from around the anode or on the neck.

Any tips on getting my blast raised from the dead? I will try to get some decent pictures showing the connections, but as of yet they all seem to stink. Bad lighting :/

 

[Nerdygrrl]

First off I would recommend not powering this on anymore, you can do some serious damage to your chassis. Hold off, get some decent pics and let's make sure this is wired up correctly.

When you say your monitor dies a few weeks ago, what happened? What lead you to this diagnosis? What were the symptoms?

When you say "fireworks" do you mean actual sparks like an arching flyback or are you getting sparks in the tube?

 

[thieslo]

It went from displaying an image, to nothing. I had turned it off and back on and actually got an image again (nice bright image), but then I turned it off, swapped PCBs and then had nothing again.

As far as fireworks, I mean sparks in the tube, no arcing electricity anywhere I shouldn't see it.

 

[thieslo]

Here are the pictures.

First up is the connection of the power/VGA signal. The one AMP connector is connecting to the front of the frame and attaching to the cab, then the VGA cable goes to the neckboard.



Second image is the degaussing cable connecting from around the monitor to the chassis.



Third image is the monitor ground going to the neckboard. Pretty sure this one is right as it is the only single connector to single connector.



This one is kind of hard to see, but here are the two sync cables going to the middle of the chassis. Pretty sure i have the one on the right side as it only seems to fit on one side vs the other.



Final image is of the entire neck (I know not the greatest picture). This is where the "fireworks" happen. Inside the glass tube there. It also seems to be the source of the high pitch squeel.



There are no electrical arcs anywhere, just contained inside the tube. The tube itself from the front, I see no activity, not even a brief flash of anything.

 

[Nerdygrrl]

So the tube is actively sparking, not a continuous neck glow, but sparking?

Was this chassis tested previously?

 

[masamuneGTO]

If it is sparks in the neck then your anode voltage coming from your flyback transformer could be too high. Check the B+ voltage to make sure it is within spec. The other option is there is a crack somewhere in the neck/tube, which would be game over. Let's hope it is just a B+ voltage issue.

For reference: http://www.jestineyong.com/sparking-in-the-crt-tube-neck/

 

[thieslo]

Nerdy, as far as the neck, it is active lines sparking.. coming and going. They are pretty steady on one side, almost like a collapse somewhere, but it is not a steady glow, there is activity.

I will check the B+ voltage, it could be a crack from me removing it which would suck, there is the psosibility, but it wasn't the original cause as the monitor wasnt moved at all between working and dead.

Although I would think if I had any crack in the neck then I wouldn't be getting any activity when I turn it on. Checking out the website you posted now.

 

[thieslo]

Checked the B+ voltage as R33 as suggested, found it to be at about 42 V, supposed to be 55 V, moved it up and the highest I could get it to go was at about 50 V, same results. I am only messing with 15k at the moment.

 

[masamuneGTO]

Here are the +B voltage specifications for the rodotron series:
http://wiki.arcadeotaku.com/images/9/9e/Rodotron_666_Info_1.JPG

Article over on arcade otaku: http://wiki.arcadeotaku.com/w/Rodotron_666#Documentation.

 

[thieslo]

Yeah, I read both of those documents, that is where it told me to check the B+ and the 55V I picked up for a 666B, which I believe this one to be. Just sits at about 45-50V

 

[ECZangief]

Did you happen to get this sorted?