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ekorz

Multi Boyz 4 Pi
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Been living with this for a while but I feel like I should address it now that flybacks are available. If it’s the flyback... I don’t see any cracks or arcing.

this buzz is pretty consistent, I do think it gets slightly louder as the tube warms up. It will buzz at a higher rate at 24 or 31khz, though I didn’t film that tonight.

I’ll probably pull off the shield tomorrow and see if the neck board is vibrating, but, any other ideas on what to check, oh CRT wizards?

 
Does the buzz ever stop? I'll get something similar, but then it goes away.
 
Does the buzz ever stop? I'll get something similar, but then it goes away.
Nope, it never stops. if anything it’s louder after five or ten minutes. Though I may just be noticing it more.
 
Take a wooden stick and push the flyback while it's on. Just like a small amount of pressure. Does it change?
 
Could be the deflection yoke or a coil on the chassis.
 
Hm, poked at the flyback, no change. Took off the neck board entirely and it still makes the noise.

Poked at the yoke...


seems to change the buzz. That’s gotta be the source then yeah? What’s the remedy?

also had a little piece of metal pop out... you can see it move in the video when I go to the left side.

https://imgur.com/a/65NYwFM
 
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Sounds like its from the yoke, but make sure thats what it is as it could be components in the scan and power supply
circuits as well.

If its the yoke, then what you are hearing is most likely some loose windings, etc.. these sub/harmonics could also be further amplified by the tube. Only attempted fix I know for this is to remove the yoke, soak it in transformer lacquer/varnish for a couple of hours (there are some coatings that take less time, but you just want to build up a nice coat that will harden pretty good to stop the windings from vibrating), then bake it in the over for like 24hrs at 160-170 Deg F, and then allow it cool of, dry out further at room temperature for like another 24hrs and reinstall it and go through the purity and convergence setup. You could swap out the yoke and but will have to do the setup again also. Or get headphones when playing :) Alternative replace the tube.
 
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Replace the tube?!
 
@ekorz That piece of metal was likely part of the mounting tab and most likely your culprit.
 
@ekorz That piece of metal was likely part of the mounting tab and most likely your culprit.
So you think there is more of it? It still buzzes even though that piece fell out
Most Yokes have 3 metal mounting tabs so the yoke sits flush. You can even see in your pic where it broke off. That's where I would start, take the Yoke off and check the tabs.
 
Good eye @ReplicaX

Ah missed that, check that metal tab on the left side. The 2 plastic halves should have clips or snap together and the metal tab is part of the locking/mounting design, check that section out for sure.
 
So you think there is more of it? It still buzzes even though that piece fell out
I think it's more that that mounting tab used to hold it to the tube tight, but got cracked/broken and allowed it to vibrate.

Just cracked/broken it vibrated, and now that you've jostled it part just fell on out. But either way, it's not mounted tight anymore.
 
So you think there is more of it? It still buzzes even though that piece fell out
I think it's more that that mounting tab used to hold it to the tube tight, but got cracked/broken and allowed it to vibrate.
Just cracked/broken it vibrated, and now that you've jostled it part just fell on out. But either way, it's not mounted tight anymore.
This. It's probably loose where that mounting piece came apart.
 
I’m guessing this isn’t an off the shelf part I can find somewhere...

the piece slid out from between the coil and the plastic part of the yoke. I thought mounting clamps were more along the neck of the tube. Here’s a still frame

apNR2cF_d.jpg


Hardly seems like it’s mounting anything to the tube. Maybe it’s mounting the coil to the plastic?

either way sounds like I need to get this on a bench. Gotta clean off the bench...
 
Alright. Pulled it out and put it on the bench. I took off the yoke and I’m noticing a few things.

First, no clamps at all. It was glued in.

Second, lots of convergence strips.

Third, some crusty fried parchment inside the yoke.

MqHmj4h_d.jpg


More: https://imgur.com/a/hMgOQWV
Vid:

what say ye sages?
 
So that's where the paper comes from... Every blast chassis I've gotten in recently has bits of that same paper strewn across them. How weird.

No advice from me, don't know anything about yokes.
 
The more you know....

honestly I feel like the vibration was probably a lose piece of something in there, or just that the yoke itself wasn’t really secured well.

I don’t see any harm in just cleaning it out and putting it back together. if it’s not seated all the way to the tube I’ll just get a poor image right? Would be a nice test to see if the vibration goes away. Rubber gloves time!
 

Ok so I removed the yoke entirely and powered it up. It is the cause of the buzz. It buzzes even when it’s not touching anything else. I couldn’t find anything loose really. Hmm... do we do the @Derick2k method?
 
Take this troubleshooting with a grain of salt. I am no expert on yokes, but a friend and I have removed them. So I'm not completely clueless.

I notice the buzzing getting louder when you turn the camera towards the front of the yoke, as if the sound is being amplified by its cone shape.

If I'm correct, that would point to something in the back creating that sound before it enters the cone.
 
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