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Weird magnetic interference after tube swap… Help!

BuddyC

BuddyC

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Got a real weird one here. Got me totally stumped….
Long story short. The Toei chassis in my SNK MV25UP-0 died a couple of weeks ago. Flyback craped out and since there are no replacements for this flyback (as far as I know…) my only real option is to yoke swap in a MS9 yoke and chassis.
On the original Toshiba tube I could not get decent purity and convergence, so I tried a different tube I got from a fellow arcade nerd.
Tube is a Videocolor a59eas13x01 and came with a Hantarex MTC 9110 chassis.
I did a successful yoke swap to MS9 yoke and chassis. Great geometry and convergence with good purity…
Great success….. I thought…

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No issues. Rock solid image.
But when I put the tube back inside the cab this shit happends…

Whit the front cover closed. Magnetic interference
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Start to open it up and it gets better

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And a little open

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And almost gone when completely open

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Gomes back the moment I close the front again….

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This shit got me completely stumped….
I have degaussed it multiple times with my big degaussing ring. Didn’t do shit.
Original tube and yoke combo was grounded. This one is also grounded like the original.
No other type of interface. Just magnetic. From the monitor cover as far as I could tell.
Tube is perfect when I remove it from the cab again.
I also set up purity with the screen facing east…. Don’t know if that matters, but I did it by the book.

Any tips? You have the same cab, right? @nem
 
Are you degaussing it with the cover closed or open?

I have the same thing with one of my wangans. The steel has become slightly magnetized somehow, putting the back cover on causes purity issues. I just degauss it after it's all closed up and it's fine.

BTW, what toei is it? If it's the TC-RM251S, APAR stocks a repro flyback: https://www.arcadepartsandrepair.co...acks/toei-y261753-tc-rm251s-tc-rm29j-flyback/
 
Thanks for the reply! I tried degaussing with both the top open and closed. Didn’t work.
 
Yeah, you need to degauss it with the hood down.

If the degauss coil on the tube isn't doing the job right, you need to use an external degaussing tool. However, that can be difficult, since the tube is pretty deep inside the cab.

I assume you connected the original degauss coil from the tube to the MS9 chassis?
 
nem said:
Yeah, you need to degauss it with the hood down.

If the degauss coil on the tube isn't doing the job right, you need to use an external degaussing tool. However, that can be difficult, since the tube is pretty deep inside the cab.

I assume you connected the original degauss coil from the tube to the MS9 chassis?
Click to expand...
Yup. I used mye big external degaussing ring also. Didn’t help at all.

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What about the degauss coil on the tube? Did you remove it, or is it not connected?
 
Likely some piece of metal on the cabinet itself has become magnetized. If there are any metal parts on the hood for latching etc, try removing them to see if you can isolate it to a specific piece. Few ways to try and fix this after you figure out which part it is.
 
What a gorgeous machine. Im gonna follow up here and also say its possible that the metal hood or something in there has become magnetized a bit. I got the same demag wand and those are pretty powerful usually.

Anyways:
Never tried so may not even work, but maybe you can get some of that magnetic field viewer sheet stuff and move it around the body of the cabinet and around the edges of the tube to pin point whats actually causing it. Its gotta be a somewhat strong field if its influencing the purity in the tube.

I have also heard tales about the band of the tube becoming magnetized somehow but if its actually on the tube why does the problem show up when you put it into the cabinet?? You arent using a drill to put the machine back together?? I heard doing that can some times do funky things.
 
GeekMan1222 said:
What a gorgeous machine. Im gonna follow up here and also say its possible that the metal hood or something in there has become magnetized a bit. I got the same demag wand and those are pretty powerful usually.

Anyways:
Never tried so may not even work, but maybe you can get some of that magnetic field viewer sheet stuff and move it around the body of the cabinet and around the edges of the tube to pin point whats actually causing it. Its gotta be a somewhat strong field if its influencing the purity in the tube.

I have also heard tales about the band of the tube becoming magnetized somehow but if its actually on the tube why does the problem show up when you put it into the cabinet?? You arent using a drill to put the machine back together?? I heard doing that can some times do funky things.
Click to expand...
No drills or other power tools. Just a standard screwdriver. Will do some more detective work today and go to town with my degassing ring. Fingers crossed…
 
BuddyC said:
Tried it with and without it. No difference. Weird as shit…
Click to expand...

Is the coil actually firing? Like if you use your external degaussing tool and make a mess of the colors, does the degaussing coil revert it to normal colors?

Reason I'm asking is because degaussing coils from two different tubes are usually not the same. If you're using the original coil of the A59EAS13X01 it likely has a different inductance and resistance compared to what's on a A68KJU96X that's normally paired to a MS9. Try measuring the coils.
 
Based on prior experiences, flybacks from HR Diemen is hit or miss…
Still hoping for this MS9 craziness to work out.

Looks like the entire cab is kind of magnetized. My big ass degaussing ring is working, but can only be used a minute on and off before it needs to cool down.
Still hopeful 🤞🏻
 
Did this machine come from China by chance? I have seen this with a few of the Candies out of China. Makes me wonder how they are being stored/what they are stored next to.
 
Could be, but I have owned the cab for years. Previous owner had it here in Norway for 10+ years and this is the first time this has happened.
Could be that the Videocolor a59eas13x01 tube is super sensitive to magnetic interference? 🤷🏻‍♂️
 
Nevermind then. Wonder if you are close to an electrical panel or similar. You can always buy shielding sheets to prevent this but kind of pricey and may be difficult to apply in this instance.
 
Since it’s never been a problem before, my best guess it’s the new tube. Will need to do some more experiments tomorrow.
 
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