Nanao Monitor Squeal from Neck Board

Gambeno

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I have an issue with my 29'' Nanao monitor that I can't seem to figure out how to correct. The problem is this, when I first cut the monitor on the picture is all fuzzy, but after about 4 minutes it looks fine except for these little white specks floating all over the screen (only visible on a black background). The monitor also makes a loud squeal noise coming from the back of the neck board on the tube (pin pointed the noise using a paper towel roll). Sometimes if the noise stops, the white dots go away so i know the problem lies with the noise coming from the neck board. I also took the neck board off the tube and notice a build up of white stuff (Oxidation?) on one of the 9pins (very bottom one). Not sure if that has anything to do with it or not. Any help would be great! Really would like to stop the noise and fix the white spots cause it can be really annoying at times.
Thanks,
Kane
 
Sounds like you're getting arcing around the focus pin. The focus pin carries hundreds of volts, and it's the one separate from the others. Try to clean up any oxidation or other corrosion on the pin in the socket, and make sure the tube pin is clean. The focus wire connects to the neckboard socket separately, and you should be able to open the socket and get better access to that pin.

Worst case scenario, replace the neckboard socket.

-Ian
 
Good call on the neck board socket, as soon as I put it on my work bench I notice that the neck socket is completely loose on the neck board. I can almost pull it off its so loose, which can't be good. Going to resolder the focus line on the socket and resolder the neck socket to the board and see if that helps. I hope this is the problem.
Kane
 
No good, still the same problem.. Argh!

Are you *sure* you got it all cleaned up? HV is funny stuff, it'll jump small gaps. In fact, there are some spark gaps built in to the neck socket, to allow it to jump to that first instead of arcing to other things if something goes wrong. Problem is, once you get dirt in there to make a conductive path, the gap gets "smaller", and it'll arc there more and more often.

Are you sure you got the tube pin cleaned up properly? And that the focus pin is making proper contact? And that the spark gaps are clear? And the solder joint on the focus pin is rounded, rather than pointy (encouraging arcing)?

Try disconnecting the focus lead entirely, and insulating it - put it down into an empty glass beer bottle or something. Just for a test. The monitor will be fuzzy as all hell, but you shouldn't get that squealing noise. If that's the case, then your problem is most definitely related to the focus voltage arcing.

You might need to replace the whole neck socket. If it's a standard socket, then you can just scavenge one from a television set or other junked monitor.

-Ian
 
I'll try again tonight. I have another 9 pin Neck Board socket from another 29'' Nanao board. Maybe I'll swap it out and get some canned air and try to get any dust out of there.
 
Btw anything you recommend to clean the pins with? is rubbing alcohol ok?
Kane

Yeah, rubbing alcohol is fine. Anything really, just make sure you don't bend or break them. If they're really corroded you might have to use something a bit more abrasive, like fine grit sandpaper or something. The tube pins aren't plated, they're a solid soft metal of some kind.

-Ian
 
I think I found the problem, and I don't know how I miss this but there seems to be a mark in my neck board that's causing a jump of electricity and I didn't notice this at all before not until I change out the Neck Board Socket. Anyway to fix this from jumping? anything that could possible cover it up with? picture below.
 

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Wow. Now that is kind of a weird one. The solder mask appears to be damaged on that trace, and it's so close to that pin - man, seems almost like a design flaw there. Anyway, to fix it, completely desolder that pin and resolder with fresh solder to ensure you remove any pitting or carbon buildup. Then clean the section of the trace that it's arcing to and re-insulate it with something. Nail polish should work - paint the exposed area of the trace with it and allow it to dry. Maybe put on two coats. And yes, you can get clear nail polish :)

Another option, seeming as though that's a ground trace that's already duplicated elsewhere, is to simply cut out and remove that section of the trace. Using a knife, you can cut the foil a 1/4" on either side of the arcing point, and peel it off. Notice that that trace is part of a big thick piece that goes all around - removing that one little section wouldn't disconnect anything - although if you were paranoid you could bridge elsewhere with insulated wire, farther away from the pin it's arcing to.

-Ian
 
The Finger Nail polish stop the spark gap, but the picture is still showing those specks. Man, this is the craziest thing. maybe I'm not soldering the focus wire back properly?
Kane
 
The Finger Nail polish stop the spark gap, but the picture is still showing those specks. Man, this is the craziest thing. maybe I'm not soldering the focus wire back properly?
Kane

Is the DAG ground wire connected? I'm guessing it's not, if you're getting arcing and sparkles like that...

There should be a wire that goes from the spring across the bell of the tube to the neckboard.

-Ian
 
I re soldered the neck socket and applied the nail polish a second time and everything is working great so far. I left it on for about an hour, hopefully it will stay working this time.
 
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