Taking care of an old SEGA monitor
MS-2930-S
Hmm.. Bad grid, yeah. And the monitor is making a low buzzing noise.

I wonder why.
Oh! That's why.

Dried up tape and only crumpets left of what used to be some sort of induction inlays, or magnetized plastic.

And, .. dear Joseph, Mary and a baby dinosaur! Is that the yoke body cracking up?
The convergence correction isn't working at all. Everything around and under the yoke has been roasted like crispy crackers, and had to be either knocked or pealed off with a knife.

This monitor has been locked up inside a hot place for a very long time.

What can we do?
Well, we can start by cleaning up.

No, not oursevles. The yoke and CRT area that we want to work with!

Putting the chassi aside for later re-capping, we remove the daughter board and some of the larger components, to be able to clean it better. We ... What's that?
That.

It looks as if someone pooped on this chassi. I doubt it's the flyback, so that leaves us just one option.
This strange little grey cube.
Yes. It does appear that our '750 A1' coil has spilled chocolate all around.
The flyback otherwise seems clean.

So the pooper must be taken care of before it has another 'accident'.
The poop, or goop, whatever it was, cleans up easily with alcohol.
This is what I would call a *necessary measure*. Putting a diaper on this sucker will keep its excrement contained.
There you go.

I've got information that this chassi was operating inside one of these small japan made cabinets. Yes, those white plastic 29'' ones that look like astronaut-helmets.

Don't these cabinets have vents!? They are very efficient monitor-killers. We can all agree on that. Who else would we blame for all that molten goop?

Usually monitors are specified to operate in the ambient temperature of maximum 40 *C. My guess is that it is much warmer inside these air-tight cabinets.
While we have already acquainted ourselves with the chassi we can as well get it fresh and ready.

There are quite many electrolyte caps on this chassi, so we'd better make a map.

And here it is for you guys who actually want to go through with it: >> Cap-Map Large
Capacitor shopping list

All 105*C
(BP) Bi-polar
Pieces
uF
Volt
1
2200
10
1
1200
200
1
1000
35
1
680
35
2
470
250
2
470
25
2
470
16
1
330
35
1
330
16
3
100
35
1
100
16
1
47
200
7
47
16
5
22
50
2
10
35
12
10
50
1
10
250
1
10 (BP)
25
1
6,8
250
1
4,7 (BP)
50
6
2,2
50
1
2,2 (BP)
50
6
1
50
2
0,47
50


Work, work work ...

... work, work work!
A word about desoldering caps on Nanao 29'' monitors:

You should use a solder sucker for the larger caps, but when removing the smaller caps in densely populated areas, use a smaller wick. Or you could accidently suck up a surface mount component next to your target. As you can see, the board is full of innoscent bystanders.

Be quick and be precise, like a ninja.




... now where were we?

Yoke!

... with refreshments!

I'll cut the process short and show you the result.

Basically you impregnate the yoke as much as you can so that cracks and crevices are shut and fastened.

No special moves or combos, just put the stuff in there. I used the spray first, generously, and let dry. Then the white smear.

The spray is called 'Plastic Spray' and it's for circuit boards and electronics. The white stuff is called 'Akrylfog' in swedish. I don't really know its composition, but it's sticky, rubbery and flexible. So it does the job I need it to do.

This should shut the yoke up eternally.


So, now we have a nice yoke, a really nice and clean restored MS-2930-S trisync chassi, and a pretty CRT. All waiting to be asseblmed and powered up. But there is one small problem still that we need to take care of, otherwise we won't have the picture this monitor was initially blessed with.


Looking down on what we have at hand, it's not much we could use. Is it? Crumpets mostly.

So how can we create some inductance around the cathode guns to correct the convergence?
We must use what we have available in our kitchen. In this case ... a small box cutter knife, some paper, isolation tape, and some double- sticker tape.

We cut out a few 10 x 100 (mm) pieces of hardened paper. Normal paper should be OK, but I wouldn't, no.

Chip off accordingly few pieces of the knife's blade and use one layer of isolation tape around it.
Like this.

Securing these 'inductor-sticks' can be done by simply taping them to the CRT, or as I've used some of Camilla's double sided sticker tape.

Important is that the metal part is isolated. Why, I think I don't need to explain.

But with no more than one layer of tape. because we want to move this little rod freely under the yoke, looking for its 'sweet spot'.
Remember our first view of the grid? Well, here's a new grid that M.Matsushita would be proud of.



After all it is his work we're restoring here.
I used five of my six induction-sticks to balance the edges into an almost perfect convergence.

Here's a trisync that will last another 20 years, hopefully.
Putting some duct tape under the yoke clamp, and the ring clamp, will help these devices to stay well in place. Otherwise there's a risc of movement. Make a final inspection of how the inductor sticks are placed onto the neck (right).

Then secure the yoke from at least three directions with the rubber wedges and duct tape. And, to further inhibit rotation and vibration, some white goop between the yoke and wedge.


* * *

Thank you guys.
Thank you, Linus, for bringing me this monitor to play with,
... and thank you for taking it away.

It means alot to be able to help out regaring these beautiful old monitors. Don't worry about hazardous shocks or lethal accidents. We all learn by experience. If we only followed theory, we would be stuck in the library.

The bottom line is:
If you don't know what you're doing - find out.