Astro City monitor squealing

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    • Astro City monitor squealing

      Hi everyone,

      My Astro City's monitor recently developed a strange noise. It makes a squealing sound at a very high pitch but it only last for a few seconds. Then it'll come back. I don't think it's capacitor related, not that it couldn't use a re-cap but the image looks normal.

      I did some googleing and came across this thread. forum.arcadeotaku.com/viewtopic.php?t=26922 - I'm not sure if that's what I'm dealing with or not.

      I uploaded a video to youtube so you can hear the sound it's making. This recording isn't too bad of an example but I have heard it much worse in the past. You might need to use headphones to make the sound out. Sorry.




      I haven't used the arcade since, but if you'd like me to take another video to get better sound or do anything else please let me know.

      Thanks!
    • Mitsurugi-w wrote:

      In my experience that sound usually comes from the ferrite core of the flyback resonating. The fix could be as simple as using a toothpick. ;)
      Thanks for the suggestion. Is there a documented process or video on this technique? Sorry I’m pretty ignorant with this stuff.

      rewrite wrote:

      Also, if present try screwing the mounting screws for the flyback in tighter.
      I believe they’re on pretty tight but I could give that a go.

      I uploaded another video if it helps. Thanks all!
    • Magus wrote:

      Thanks for the suggestion. Is there a documented process or video on this technique? Sorry I’m pretty ignorant with this stuff.
      Look at the flyback. You will see a round piece that goes down through the middle of the flyback. It can be hard to see the actual core on some flybacks. There is usually a plastic sleeve that goes down through the middle of the flyback and then this ferrite core is installed through the sleeve. It is usually very tight and sometimes when the monitor is operating the core will vibrate rapidly and cause the squeal. This is called resonating. Think like if you hit a tuning fork. Same sound, yeah?

      On some flyback a you can stick the tip of a toothpick between the ferrite core and the sleeve. Some you can easily do this from the top. Some, like many Nanao monitors, try to seal the gap in production and there is no way to do the easy fix. Some flybacks you can remove and do this fix from the bottom and re-install it. I know several people, back when I collected mostly older and 90's stuff, who would use this method to fix the squeal. I've done it a few times myself.

      Some people are super sensitive to the sound and it drives them nuts. Those people would have no issue desoldering the flyback to do the fix and then resolder it in even though it is a pain. :)
    • Different noises seem to come and go on my cabs. The flyback, coils, the deflection yoke, they can all whine / squeal. Honestly, if there's no smoke, I wouldn't worry about it. Turn up the volume on the cab, or wire in a high to low converter and connect a set of headphones if it really bothers you.
    • So this is a nanao ms8-29, The noise come from the flyback and maybe from the deflecftion joke. You shuold replace all caps on power section including the big filter one (high ripple block) than check and adjust the B+ after that you shoud have solved otherwise if you still get noise you can try to put some glue on yoke copper winding.
      you must check this resistor 1.8kohm (should be r542) and you must take a look under the board for dry solder joints and reflow them just under the resistor mentioned (photo in attach).


      Very important: have seen your monitor better and it seems to have a different yoke than a ms8, it could be a sanwa pm1745 if its so all my advices are useless, please make a photo on the chassis and one on tube label.




      Update:
      Images
      • powersectionR542.jpg

        82.25 kB, 360×480, viewed 27 times

      The post was edited 1 time, last by Mukuro_W ().

    • Ok its truely a sanwa pm1745 chassis paired wirh toshiba or Samsung tube, same ms8/ms9 curvature but different yoke value, obviously. Usually Astro City comes with nanao MS8-29 but this is not on your cab. The sanwa is a good monitor sometimes suffer of ground issue.. it have the same flyback of the Ms8 29, you should take a look at resistors in power section and all caps in this area just near the big filter one. I will let you know with more detail once I take a better look at my chassis.