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Issue with NNC D29C051 monitor shutting down

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nitsua55

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Hi,

I’ve been searching online for past cases to explain the problem I may be having with my NNC tri-sync monitor.

I believe there is an issue with the chassis when the vga signal is passed in and it shuts down.

Monitor comes on fine and only shut down once the vga signal is passed through. I’ve tried both the 15khz and 31khz setting on my Naomi and it produces the same results. The neck glow and chassis itself look fine, but open to starters before I pull the chassis out and take a closer look. I suspect the issue is with a bad out of spec resolution being fed to the chassis.

Video of the issue:
View: https://youtube.com/shorts/Wdm0z-rg5-4?si=aUebRzwNhWOUj3Ns


Thanks!
 
Giving this a bump again.

I probably should have provided a bit more detail as well…
The chassis is a toshiba pd2367 with a matsushita tube.

I’ve recapped the chassis and tried replacing the signal processor IC C1888 at Q405. Neither seems to have resolved the issue with it shutting down when a signal is passed.

Open to any other suggestions or ideas as to me the issue looks like a problem with the resolution being passed.
 
Looks and sounds like the flyback is arcing and then goes to safety shutdown. Have you turned off the lights and looked at the chassis and anode cup while powering on?
You should see some arcing that will point you to the fault.
 
At 23 sec in your video, you can see something arcing inside the neck of your tube 😬
Could be that one of the color guns is shorting out on G1 or the heater inside the neck, but you need a rejuvinator to find out. Hate to be the bearer of bad news, but unsure if this is fixable…
IMG_2589.jpeg
 
Last edited:
Thanks, that is what I feared given I just vetted the chassis on another tri-sync and it worked fine.

I’ll have to see if I can get the tube tested then to see if this one is bound for the graveyard :(. Very sad.
 
I fixed a Toshiba tube with my B&K 467 rejuvinator that had the same issue as your tube. Fingers crossed it can be repaired.
Best of luck!
 
I’ll look into getting it tested and report back how it goes.

Was it just a clean / rebalance you had to perform or a remove shorts in your case?

Thanks again.
 
Full, hardcore rejuvenation. Multiple times….
Not good for the longevity of the tube, but fixed it.
 
We are back in business!

https://imgur.com/a/jpSpBsl

Got a 470 on the cheap. Initial tests were all good outside of the green gun flagging as bad.

Looks like a clean/rebalance brought all the guns in line.

Will run it through its paces over the next while to see how it goes. Only thing left to do is try to address some convergence issues that remain.

Thanks for chiming in BuddyC.
 
Wait, your PF was shutting down its own, you rejuvenated the green gun, and now it's not doing it anymore?

Wow. Good call, @BuddyC.
 
To be fair, I also capped the chassis, but that changed nothing.

I ran the rejuvenation on all the guns for good measures, but only the green one was flagging in the red.

Either way, appreciate the help with troubleshooting and getting it back to a working state!
 
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