Blast City – Monitor 2931

Originally posted Oct 6, 2020

Joey advised that he worked on both chassis and was able to bring them back to life so they were operational. He also stated that he used the last 2931 flyback he had so that was a bonus.

They arrived and looked brand new compared to what they were when they were sent to him.

MS2931

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MS2930

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I couldn’t decide which chassis to test first, so I decided to go the 2931. As soon as I connected it, I was in awe of the picture quality – but something was “off”. After trying to adjust the display, the best image I could get wasn’t a full screen image, it appears to have been zoomed in by about 20%

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I reached out to Joey and he asked me to try and make adjustments on the B+ pot

As you can see in the video, the image slightly adjusted – but nowhere near enough of what I am expecting.

So I decided to work on the other chassis, the 2930.

Connected it all up, and upon turning on, I got background image, but I couldn’t get any red or green on the image and no amount of turning the gain pots changed the image.

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By this point, I was extremely frustrated with both chassis and I’ve always heard how much of a PITA they were. Reached out to Joey again and he said to check the neck board for some loose transistors, they seemed fine, so the only thing I could really do was to send the chassis back to Joey for further inspection.

I was ready to cut my losses and call it a day……

But me being me, I am quit stubborn and I don’t like to wave the white flag so easily so I thought I’d do some trawling on the interwebs :D  :D

After reading numerous threads, I believe I came to the conclusion that the flyback being used on the 2931 is not an original nanao. Whilst new, it wasn’t a complete 1:1 and it seemed to point to that direction. So I decided to try my luck and roll the dice.

The plan was to do some electronic surgery :) remove the flyback from the dead 2931 and put it on the newly refurbished one to “test” the theory! Never worked on CRT’s before at this level, I was packing s**t!

10 minutes worth of desoldering, I was able to get the flyback off both 2931’s. I was a little weary about the flyback as there appears to be a break on the anode cable.

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I still went to test – curiosity got the better of me.

After installing the flyback and the chassis back to the monitor, I turned it on – expecting arcing, or a loud hum, noise.. I was greeted with the following image

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WINNER! so I thought!

The original flyback clearly shows the image is much smaller than the other flyback I had. I started adjusting the image, and then a few funny things started happening which got me scared so I turned it off.

Check it out from 47 seconds…

Called it a night as I was a little too scared :D

The following day, I spent some time reading through more threads and with the help of djcalle, he pretty much confirmed that the MS2931 and MS2930 share the same flyback. I have 2x dead MS2930’s but may have working flybacks.

So I decided to once again desolder the flyback. Nice and clean!

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Flyback cleaned and dusted – it was at this point I realised why some monitors may potentially die. All the black goop appears to have gone on a pin on a flyback and I couldn’t get any form of continuity from the pin to the top where the black goop was.

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Installed the flyback and kept everything crossed and hoped that nothing exploded on me when I put the power on…..

Voila! Perfect 15khz full screen image!!

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I let the game run on for a lot longer and I got 30 minutes without any funny zooming in or anything like in the previous video

Big massive win for the 2931. Next up tackle the 2930.

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