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MS9 gone wicked blurry [UPDATED]

NFGx

NFGx

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[UPDATED: see solution post below]

So my MS9, recently returned from a service, has developed a serious problem.

Once or twice before it has turned on from cold with a very impressive blur problem. Like, 20% of the screen sort of blur. It resolved gradually over ~5 minutes, and then didn't happen for a couple of weeks, but this time it's started making a fizzling noise at the same time. The brighter the screen, the fizzier the fizzle. Then I noticed a subtle flicker in the brightness levels. And then, after re-seating the neckboard and checking all the wiring for loose bits, it started to flicker with horizontal lines, as if it was trying to collapse vertically.

It's going back for a second look from the shop, but I'm wondering in the mean time if anyone has any ideas about the cause of these symptoms?

Attached is the blur. You can see by the light reflection that the focus on the camera is good, but that rolling static background and text display from a MiSTer board are completely fucked.


20230604_210501-picsay.jpg
 
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I had a monitor with similar focus issues when cold (fixed itself in like 3 minutes), sent it to TKS and they had to replace the flyback.

The flyback gets noisier with bright screens, which is normal, but if makes more noise than usual that is another pointer to the flyback being the issue IMO
 
Could be just the crt socket wich need to be replaced on the neck board, you do not need the same but just same pinout.
 
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Thank you both. Hopefully the shop can identify a problem in the chassis.
 
There is also an issue when the step down do not supply ia minimum of 3A AC , if less the tube will stay more out of focus on cold boot at start up ....
 
I would check the focus wire on the CRT socket on the neck board
I seen it happen where the solder joint/ wire breaks off the focus wire solder lug and well there goes your focus. Theres a door that covers it so even if the wire looks okay it could be disconnected inside the socket or have a bad solder joint.

Open the cover inspect and reflow solder etc if needed

The fly back could also be going out but start with the easy things
 
Mukuro_W said:
There is also an issue when the step down do not supply ia minimum of 3A AC , if less the tube will stay more out of focus on cold boot at start up ....
Click to expand...
I don't think that's it, the transformer is HUGE and it's been in operation for many years before I got it. Interesting suggestion though.

GeekMan1222 said:
Open the cover inspect and reflow solder etc if needed
Click to expand...
Oh for sure, I did this. It had just come back from the shop, so I didn't expect any cold solder joints, and indeed, didn't find any. Not visually anyway, and since it's under warranty I didn't want to poke around too hard.

advans14 said:
Yup. Could be flyback. Could be focus wire. Could also be corroded neck socket pins Or moisture.
Click to expand...
The sizzling, crackling and flickering does not fill me with great joy, and indeed the flyback was my first suspicion. And also, my biggest fear, 'cause it seems to me they aren't easily purchased these days.

I wiggled all the wires and re-seated the neck board a few times to no avail. Whatever the problem might be, it doesn't seem to be a loose or bad connection.
 
OK, so I got the report back from the shop. The important summary:

The neck board at some stage was exposed to water or moisture so the high voltage must has been arcing slightly causing the PCB to carbonise in that small section.

The only way to fix this is cut or drill out the path, I chose to throw it in the bin and put a much better neck board on the chassis for you.
Click to expand...

So yeah, high voltage arced under the neckboard socket, causing it to carbonize and become conductive, and focus voltage was going straight to ground.

I quote more from his summary:

Very unusual in that when something like this happens with focus or screen voltage being such low current it would normally stop the focus working at all or the screen would blank.

It was on the border of stopping and cleared up marginally as the PCB warmed up but soon that wouldn't have any effect and it would have stopped displaying anything.

Funny enough it wouldn't have damaged anything.
Click to expand...

So, yeah. I doubt I'd have ever found that problem on my own!
 
NFGx said:
So yeah, high voltage arced under the neckboard socket, causing it to carbonize and become conductive, and focus voltage was going straight to ground.
Click to expand...
Didn't think you'd ever have to worry about your carbon neckprint, huh?

Funny enough I was reading about this earlier, how rarely focus can be lost due to carbon build-up.

Found this lovely site here: https://www.repairfaq.org/REPAIR/F_monfaq.html
 
I wonder if the chassis was washed when it was originally being serviced.
 
nem said:
I wonder if the chassis was washed when it was originally being serviced.
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Jomac knows their stuff. I doubt they caused it. Most likely it was life in humid Queensland that did it.
 
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You can try to replace the CRT socket on the neck board, you can find this from lots of brand but all will do the same job. The part is GZS10-2-108

GZS10-2-108​

 
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Mukuro_W said:
You can try to replace the CRT socket on the neck board, you can find this from lots of brand but all will do the same job. The part is GZS10-2-108

GZS10-2-108​

Click to expand...
The whole neck board has been replaced by the shop, but thanks, it's good to know the part number.
 
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