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Nanao MS929 loud squeal post cap replacement

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Bad_Hambre

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As the title says, my nanao is making a very loud squeal. I did found that I messed up in putting c211 with the wrong value capacitor. It is supposed to be a 2.2uF but I had a 100uF in its place. I haven't tried powering up again after that fix. But I'm not certain that's where the problem is. What do you guys think I should look at before powering up again? Or do you think having the wrong capacitor was the main issue here?


View: https://youtube.com/shorts/NAgmNl-Vs1s?si=mNFVln1J8BA8XWiF
 
Update: I forgot to mention that there was no picture on the tube. Was not sure if it was turning on or not.

I changed the cap. I might try powering again, but would like some advice to see if that's a good idea. I have searched flybacks on ebay, but looking like I have to pay more than $100 for one. I also have another working chassis, and can do a swap between them for the flyback. But was wondering if that was a good idea or not.
 
Polish-Jack said:
It sounds like it could be coming from the power supply transformer.
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I dont think it's from the power supply since i have tested other boards and it doesnt make that noise. I'm also using a step down transformer to power up the arcade. But I don't think it's coming from that either.
 
Polish-Jack said:
automotive stethoscope
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Just looked this up, seems very handy for what i got. And affordable too.

I am curious, most of these are steel, would it be ok to make contact with the transformers while the tube is powered up?
 
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Bad_Hambre said:
Just looked this up, seems very handy for what i got. And affordable too.

I am curious, most of these are steel, would it be ok to make contact with the transformers while the tube is powered up?
Click to expand...
I just put some heat shrink over the rod and left only the end exposed.

You can also get a medical stethoscope and just use an open rubber tube. It helps track sound too.
 
Oh. I almost forgot. You can try using a smart phone too!

Download the Spectroid app. You will see a peak on the graph and you can poke around with the microphone end of your phone to see where it is strongest.
 
Have you figured out what the specific issue is? I was experiencing the same exact behaviour from my board, but I just ended up getting it professionally serviced, because I wasn't able to diagnose it myself.
 
I had a smiliar squeal and it turned out to be one of the small knobs on the flyback, when I touched the knob the squealing went away. Can't remember if I used a toothpick or some Blutac to quieten the squealing.

Your mileage may vary.
 
kazuma said:
Have you figured out what the specific issue is? I was experiencing the same exact behaviour from my board, but I just ended up getting it professionally serviced, because I wasn't able to diagnose it myself.
Click to expand...

Not yet, last few weeks were pretty busy and kept me away from working on the boards. I do plan on getting a stethoscope like advice in this thread to see if I could isolate the source of the squeal.
 
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