Nanao MS9-29A Video Interference

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zed7
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Nanao MS9-29A Video Interference

Post by zed7 »

Hello everyone, I'm quite lost on how to fix this predicament. I have got some sort of interference in the picture for this monitor, and I've been struggling to figure out what it is.

Here's a video of said interference.

What I've done: cap kit, minus 3 of the 100uf 35v capacitors, as I did not have them. This includes the filter.
Replaced the HOT

What I've looked into:
Confirm the PSU GND and Video GND are connected - they are via game PCBs.
Sync trace is intact, but solder mask is damaged. Continuity check between solder joints measured ~0.8-1.0 ohms.
Chassis should not be connected to earth ground as the New Astro City diagram does not call for E.G. to the frame of the monitor.
I am not using an isolation transformer.
I have not done the G1 voltage mod (yet), so there is a jumper connecting the G1 to ground. Read more about it here.
B+ is a perfect 76v.

There may be other things I may be forgetting, but I hope that helps with finding out my issue. The next steps I am about to take (when I can) is installing those last three caps, and then scoping the PSU circuit.

Thank you for any help!
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Ericthegreat
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Re: Nanao MS9-29A Video Interference

Post by Ericthegreat »

I had same issue but filter cap fixed it, I would be willing to bet it is those missing caps if they are some of the larger ones.
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zed7
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Re: Nanao MS9-29A Video Interference

Post by zed7 »

They're one tenth the size of the filter, so it is unlikely they will fix the issue; however, I do intend to replace them first before going more extensive routes to fix the monitor
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grantspain
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Re: Nanao MS9-29A Video Interference

Post by grantspain »

the 100uf 35v caps are critical in the vertical circuit so when you get a chance replace them

that wave going through the screen looks to be external, earth/ ground problem, dirty power source, interference in signal from game board, +5 far too high on power supply

if it were degauss or filter cap fault it would be more pronounced
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