Need help with Nanao 2931 making loud hum

I have a Nanao 2931 monitor that is humming pretty loud. It arrived in this condition and I feel like the sound it is making is not normal. Full disclosure: I have next to no experience with CRT monitors.

Here is a video: https://streamable.com/e0zwk

Is the sound normal and if not what might it be?

Thanks for any help!

That squealing noise is most likely coming from the flyback on the monitor. I had that same issue with my Nanao MS9 and it was driving me insane. That high pitch squealing is annoying as shit. Never fixed Mine, just replaced the monitor but pretty sure one of the Monitor Guru's here will help you figure it out.

Try pulling out the Chassis, Do a thorough cleaning and pop it back in again.

Thank you for the reply! It was supposedly fully refurbished when I received it. That's part of the reason why the noise is concerning to me. It isn't as loud when the jamma board is unplugged and started without a game. I'm going to try VGA and see if it makes a difference.

That does sound like the flyback. However, replacements aren't easy to find to my knowledge. If it gets worse when there's video on the screen (especially white) you might need to adjust the screen pot down on the flyback itself. If you have a board with good video test try to adjust your brightness using that. Try different combinations at the flyback and on the remote board to try to reduce the hum.

Thank you for the reply!

Does a flyback making that sound indicate that is has problems or may be close to dying? I still have the option to return the unit, but really do not want to go through that hassle.

I adjusted the nob that said "screen" that was located on a black plastic box type thing and that seemed to help. It is also not nearly as loud when connected via VGA.

One thing that I just noticed is my controls are now not working. They were working fine when playing a Jamma game, but since putting this monitor in they are dead. Could that be related?

Flybacks are not hard to find they are impossible to find. Finding another chassis is the only real option with this series of Nanao chassis, that's the MS-293x series which encompasses the MS-2930,31,32,33 and 34. 2930/31/33 are all Tri Sync with the latter 2 being auto sync models. 2932/34 are VGA only chassis. just a bit of FYI.

The 'screen' nob on the flyback which is what you're referring to as the 'black plastic box' will adjust brightness of the screen and the other nob will adjust focus or sharpness of the display though I wouldn't adjust these unless absolutely necessary. eg. adjustments on the remote board aren't satisfactory.

The sound is more like a buzz than a squeal but I believe it is actually the yoke. The yoke is the large coil that sits around the neck of the CRT. Having wedged convergence strips into mine it doesn't make as much noise as it used to.

So to answer your fears, no your chassis is not dying but as you know they won't last forever (over 20 years old already!)

Chintosoccer once said that he had a guy that could, "repro" a flyback for any chassis but he needed a working flyback to do so. Not sure what that meant but I haven't heard anything from that since.

lachlan said:

I wouldn't adjust these unless absolutely necessary. eg. adjustments on the remote board aren't satisfactory.

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Could turning the screen nob up to high cause issues or something? I had to adjust them some already just to see the picture.

Is there anywhere I can get some more info on the rest of the adjustment nobs things? I have 4 other ones: B-Adju, X-Pro, HV-Adju and H-Driv.

SunsetRider said:

Could turning the screen nob up to high cause issues or something? I had to adjust them some already just to see the picture.

Is there anywhere I can get some more info on the rest of the adjustment nobs things? I have 4 other ones: B-Adju, X-Pro, HV-Adju and H-Driv.

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Just to see a picture!?

Here's a resource for the service manual.

https://wiki.arcadeotaku.com/w/Nanao_MS-2931

lachlan said:

So to answer your fears, no your chassis is not dying but as you know they won't last forever (over 20 years old already!)

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Any speculation on how long these could last if taken care of? I've seen CRTs from the 50's that still work nicely. I have 2 CRTs from the mid 90's that still look and work great. Any reason to believe these won't last 70 years like the other tubes?

c0nn0r said:

Any speculation on how long these could last if taken care of? I've seen CRTs from the 50's that still work nicely. I have 2 CRTs from the mid 90's that still look and work great. Any reason to believe these won't last 70 years like the other tubes?

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No one really knows. I've had 2 PVM Monitors die on me and they never showed any signs of failing. I'm pretty sure some of these monitors can outlast you but I guess it's hit or miss.

I think the distinguishing factor between a TV and an arcade monitor is the manner in which they were used. Is a TV on almost 24 hours a day in a Japanese arcade filled with smoke in a cabinet that is sandwiched up against other cabinets with only a little vent? no, well not the majority.

Then realise just because one monitor lasted 50 years doesn't mean every other monitor manufactured along with it will do the same and you can come to a reasonable answer. eg. No one really knows to quote Razo.

Short of custom ICs failing and not being able to be salvaged from parts, or non-replaceable flybacks, they should last a good long while.