Nanao MS8 buzzing sound

[gamezer0]

Last night I discovered a buzzing sound coming from the Nanao MS8 monitor in my Astro City. I’m not sure if it’s a sound produced by vibration or electricity. The last thing I did on that monitor is adjusting some geometry potenciometers, but as far as I can tell, that didn’t cause the issue, or at least not originally. I tried adjusting them a bit just in case, but that didn’t change anything.

The sound randomly stops at times and comes back. Playing with sound on makes it difficult to notice it, took me a few days to actually be sure it wasn’t my imagination hearing something strange.

I’m not sure which part of the monitor it’s coming from, but I’d say either somewhere in the neck or anode.

Any ideas? Other than this noise, the monitor works well.

View: https://youtu.be/XcMTLejbSx0


Thanks!

 

[ggallegos1]

I had this happen to my neo cab, it went away after leaving it on for a while. Probably dust burning off

 

[kikaso]

The buzzing could be coming from the fly back or the yoke. Here is a pretty informative thread you should read through.

ms-2931 buzz (fixed!)

 

[GeeDee]

The buzzing could be coming from the fly back or the yoke. Here is a pretty informative thread you should read through.

ms-2931 buzz (fixed!)

Seconding this. Even if this isn't your problem shot-for-shot, it's good reading for future maintenence. One of those "Well if I gotta take out the whole tube for this, better check everything!" kinda deals.

 

[gamezer0]

Thanks for pointing out that thread. I had a quick first read, but I’m too scared and have too little time (2 very small children ) to do that whole procedure at the moment. I might request a local technician to do it for me at some point though…

In the meantime, ir anyone has any suggestions / quick wins to try, let me know.

Is there anything worth trying around the anode? When recording the noise with my phone it feels slightly louder around that area… although I can’t be sure. On the other hand… I’m really scared to touch it despite having read re: discharging procedure…

Edit: one more unrelated thing. Since the first day I got this monitor, when turning it on, it initially only shows red color and slowly adds more green and blue as time goes by (it takes 3-5 minutes to show a balanced image). Presumably this would require a recap to fix?

 

[Asobu]

My MS8 had a high pitch squeel. It ended up being one of the coils which I replaced. Gently press down on each coil with a wooden utensil to see if that stops it.

 

[gamezer0]

My MS8 had a high pitch squeel. It ended up being one of the coils which I replaced. Gently press down on each coil with a wooden utensil to see if that stops it.

These coils? (I’m completely clueless, and scary, with CRTs…)

 

[Asobu]

These coils? (I’m completely clueless, and scary, with CRTs…)

Not quite. They come in all sizes and colors, but the one that was buzzing on mine is this green one.

Although if these things really scare you, maybe a professional might be better. I mean, they're terrifying, but only work on these if you're really comfortable with it. I'd hate to see you get hurt.

 

[gamezer0]

Yeah, I might just request a professional to take a look at it. Thanks for helping anyway!!

 

[gamezer0]

Today I put the back cover into its place after deciding to not try anything else and… a few minutes after power on the noise reduced its intensity but the image started shacking slightly and the red channel is now offseted a few pixels to the left

I think I’ll just ask for professional tech help but if anyone can think of any quick (and unrisky) thing to try, I’m all ears.

Thanks!

 

[gamezer0]

An update:

Over the past few days, after a tech guy mentioning it could be related to moisture, I tried a couple of things (after finding the courage to do a tube discharge for the first time ):

- I tried using a hairdryer to try removing any humidity.
- Pulled the anode cap, cleaned it, dried, cleaned the area of the cap of the tube with isopropyl alcohol, then applied some dielectric grease and put the cap back.

But the buzz persists… However I found some relevant facts:

- The intensity and frequency of the buzz is directly coupled to the V Hold potentiometer. It’s usually the most silent and constant at the clockwise-most position, and super noisy at the anticlockwise-most (video, in Spanish, sorry, but I think it’ll make sense with the previous explanation)
- I managed to improve red vertical convergence by adjusting the rings. The weird thing though, is that the rings came yellow-marked and they hadn’t moved. How can red vertical convergence be affected if the ring didn’t move? Could this be related to the buzz at all?
- As mentioned above, this tube always takes its 3-4 minutes to get all colors working (video). When turning on it only shows red. If I heat the whole monitor with the hairdryer before turning on, colors are good when turning on. What can be causing this?

 

[thegreathopper]

Which ring did you alter to adjust the red convergence, was it the one nearest to the front of the scree. I find the rings a bit confusing.

 

[gamezer0]

Which ring did you alter to adjust the red convergence, was it the one nearest to the front of the scree. I find the rings a bit confusing.

They're indeed confusing

The 2 middle rings control red and blue in relationship with each other. Using a cross hatch (I used MVS's), bringing them closer or pulling them further from each other does alter how close/far these two color's vertical lines are. If you move both of the rings at the same time, that modifies their relative horizontal distance, but (based on my last night and only experience with this) each movement affects the other dimension as well, so it's a bit tricky to get perfect. Once you get red and blue aligned, you can then move to the magenta (blue+red) vs green calibration. This time you use the 2 rings that are further away from the tube (and closest to you if looking from behind)

One trick I can recommend (I found via one of the videos I watched to know how to do this, although in that case they just disconnected the whole signal) is to turn all the way down the color you're not modifying. So for example if you're manipulating the 2 middle rings (red and blue), turn green all the way down via the remote control green potentiometer. It's also important to mark the initial calibration of them (by painting a line over all the rings) so if things go too bad, you can easily revert all the changes.

Hope that helps! I watched quite a few videos before I decided to give it a go. As long as you mark the initial position and you're careful not to touch anything dangerous, I'd say it's way less scary to do than I expected.

 

[thegreathopper]

Thanks for the tips, my problem was no marks on the rings and they were all out, the first 2 for setting the purity I still dont understand..

Mines almost correct now but Red is a bit out horizontally top and bottom but perfect on the middle third.

You sure it’s not your yoke buzzing?

 

[gamezer0]

I finally fixed the buzzing sound! It was actually some magnet that fell from somewhere and would vibrate when the monitor was on:


Video

I also sent the chassis for repair. They fixed the coloring issues (image was all red until the monitor warmed up) The culprit in this case was a leaking capacitor. They fixed it by replacing many components on this little board:


Progress!!

However upon connecting the board after receiving it back, now I ran into a new issue… the green is all messed up, like shifted projecting a shadow to the right. Any ideas?

 

[benime]

I finally fixed the buzzing sound! It was actually some magnet that fell from somewhere and would vibrate when the monitor was on:

However upon connecting the board after receiving it back, now I ran into a new issue… the green is all messed up, like shifted projecting a shadow to the right. Any ideas?

The magnet is probably from around the edge of the yoke--there's usually some mounted on the front/back of the rim that's up against the tube.

Usually C332 on the neckboard is the culprit for that type of issue (160v 10uf for MS8-26SG).

 

[gamezer0]

The magnet is probably from around the edge of the yoke--there's usually some mounted on the front/back of the rim that's up against the tube.

Usually C322 on the neckboard is the culprit for that type of issue (160v 10uf for MS8-26SG).

I found the place it fell from by comparing to the opposite side of the yoke:


How does one stick it back into its position, does it stay in place by pressure of the surrounding plastic, or does it need some kind of glue? I’m thinking of using some small pliers to put it back.

The green color issue fixed itself this morning when I tried turning the G Gain in the remote board. Not sure if it was coincidence, I’ll try it again later, otherwise I’ll check those caps.

Thanks for the help!

 

[benime]

I found the place it fell from by comparing to the opposite side of the yoke:


How does one stick it back into its position, does it stay in place by pressure of the surrounding plastic, or does it need some kind of glue? I’m thinking of using some small pliers to put it back.

The green color issue fixed itself this morning when I tried turning the G Gain in the remote board. Not sure if it was coincidence, I’ll try it again later, otherwise I’ll check those caps.

Thanks for the help!

They're usually held in place with that white/yellow silicone adhesive. They'll slot into place, but the glue helps keep them from falling out.

 

[gamezer0]

I managed to stick back the magnet back into its position. I used a thin double side tape and it seems to firmly stick. Convergence looked normal again and games looked fantastic! I couldn’t be happier.

Since everything looked solved, I put the monitor back into the Astro City, put the monitor frame back, put all screws into their place and decided to play a couple minutes of Metal Slug X to celebrate… just after picking the character, the image vertically collapsed and then the monitor turned down. Now when I try to turn it on, it sounds like it’s starting, but a second later there’s a click, turns down and you can hear the static electricity noise it does when turning off.

View: https://youtube.com/shorts/ws3As76Jdyc?feature=share


This is so annoying Anything worth trying before I send the chassis back to repair again? Thanks!!

 

[Mukuro_W]

This is the best dual freq chassis ever made by Nanao, it Is a rare variant of ms8 29 which come with the same rgb amp ic of the ms9, it has the same easy color and withe balance of the ms9 but it is alltheway sharper like any ms8, the noise is just hv leakage most likely from the anode cap, verify that and if it is the case go to replace the anode cap and metal clip. If it comes from the flyback (I do not beleave) you can cure by apply "super corona dope" Coating.