MS8-18A ''H-Size'' Pot broken

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erzane
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MS8-18A ''H-Size'' Pot broken

Post by erzane »

Hello,
I'm wondering which chassis would fit to my Mistsubishi 18'' monitor. I actually have a MS8-18A but the ''H-Size'' pot is broken.
Perhaps is it possible to replace it?
Thanks
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Last edited by erzane on December 10th, 2017, 12:07 pm, edited 1 time in total.
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Re: MS8-18A ''H-Size'' Pot broken

Post by erzane »

Joey from Jomac told me that he never seen a MS8-18A before and he thinks it was build for european market. I'm now asking about the monitor, perhaps that's the same, but I don't know if this picture reference is enough to check correctly.
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Re: MS8-18A ''H-Size'' Pot broken

Post by grantspain »

need better photo's
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Re: MS8-18A ''H-Size'' Pot broken

Post by erzane »

I added one of the chassis. I will take the monitor off and try to get better pics, pls wait.
Last edited by erzane on December 11th, 2017, 4:08 pm, edited 1 time in total.
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Re: MS8-18A ''H-Size'' Pot broken

Post by grantspain »

yep that is a ms8
what is wrong with the width coil?
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Re: MS8-18A ''H-Size'' Pot broken

Post by erzane »

Width coil don't work anymore. Impossible to set the H-Size. It's like I turn on empty. The pot inside is completely disintegrated.

A new pic of the monitor (warnings are in english & ''french''...)
Image

Some new pics of the chassis:
Image
Image
Image
Image
Image

Some of the width coil:
Image
Image

I'm wondering what about those two pots. Left: another pot for ''H-Posi'' - Right: ''V-Line''?..:
Image
Last edited by erzane on December 11th, 2017, 4:09 pm, edited 1 time in total.
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grantspain
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Re: MS8-18A ''H-Size'' Pot broken

Post by grantspain »

the ferrite core needs replacing, only way you will find another width coil is on a scrap chassis

the width is controlled by that coil and the width jumper, width coil will only give about 3 cms adjustment. the jumper will give more

the other pots are horizontal sub position and vertical linearity
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Re: MS8-18A ''H-Size'' Pot broken

Post by erzane »

Where is the ''width jumper'', perhaps this one should be enough?

About the other pots:
-is ''horizontal sub position'' a sort of very light rotation of the image?
-is ''vertical linearity'' the fact to put the geometry to the very center by making all cross/squares in the dot cross hatch to the same same dimension/harmony?

What do you think about the fact that the warnings in the monitor are written in english & french, not in japanses?
Thoses warnings looks in english & japanese on this picture but I can't see clearely due to bad resolution of the picture (normens pony)
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Re: MS8-18A ''H-Size'' Pot broken

Post by nem »

erzane wrote:Width coil don't work anymore. Impossible to set the H-Size. It's like I turn on empty. The pot inside is completely disintegrated.
That's because it's not a single turn potentiometer like everything else on the chassis. It will take multiple turns from one end to the other. I'm not saying it's not broken, but it functions differently compared to a pot.
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Re: MS8-18A ''H-Size'' Pot broken

Post by PrincessPrinPrin »

The monitor was made by Nanao not Mitsubishi. To make the monitor Nanao bought components from various sources and they bought the tube from Mitsubishi. The label on the tube was put there by Mitsubishi and they used english and french because they are important languages and their tubes were sold everywhere. It's a common practice on all their tube labels:

https://wiki.arcadeotaku.com/w/File:370JMB22-TC03.jpg
https://wiki.arcadeotaku.com/w/File:M51LRY22X62.jpg
https://wiki.arcadeotaku.com/w/File:A63LCC61X.jpg

Bottom line: IT'S IRRELEVANT.

The really important questions are: where is the ferrite core? Completely off the coil/lost? A bit broke off and another bit is still in the coil?

Anyway, the core can be replaced with one from another coil, not necessarily from an identical chassis. European arcade monitors also have width coils and even if the cores have a different thread it wouldn't be to hard to get then to fit the coil on the Nanao chassis.
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Re: MS8-18A ''H-Size'' Pot broken

Post by nem »

Oh right, I didn't even notice it's missing the ferrite bead completely. No wonder it feels 'empty', it is empty!
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Re: MS8-18A ''H-Size'' Pot broken

Post by erzane »

Thanks for your explicit explanations guys.
I see now better. So, I don't have to worry anymore since it's 100% japanese right?.

About the width coil:
Why did they use some technology like a coil instead a simple pot like in so many chassis?

I would say ''A bit broke off and another bit is still in the coil''
Btw, when I tryed to see what is inside, I took off around 40% and I noticed there was a small amount of very small dusty ferrite (bead) everytime on my screwdriver. Even the monitor was turned OFF, turning and turning inside the coil made very small changes when I turned the monitor ON.

- is it dangerous to use metallic screwdriver inside this coil?
- is it ok to set it when monitor is ON?
- and is it ok to rotate the monitor when it's ON?
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Re: MS8-18A ''H-Size'' Pot broken

Post by grantspain »

no wonder the core is **** if you used a screwdriver- you must use a plastic trim tool
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Re: MS8-18A ''H-Size'' Pot broken

Post by battlesmurf »

grantspain wrote:no wonder the core is **** if you used a screwdriver- you must use a plastic trim tool
this lol. There are plastic kits on Amazon that work great.
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Re: MS8-18A ''H-Size'' Pot broken

Post by PrincessPrinPrin »

What you need to do if the ferrite is still inside is use a regular allen wrench to take it out, with monitor off. Once it's out post a pic of it so we can see if it needs to be replaced.
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Re: MS8-18A ''H-Size'' Pot broken

Post by erzane »

Hope I can continue to use it without replacing. I'll do pics tomorrow.
Thanks for your help mates, I really appreciate;)

p.s. tomorrow I'm planing to buy this ceramic (2,6 should be ok for that coil?)
Image
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Re: MS8-18A ''H-Size'' Pot broken

Post by PrincessPrinPrin »

The core has a hexagonal hole. You need an allen wrench (of the right size), not a screwdriver.
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Re: MS8-18A ''H-Size'' Pot broken

Post by erzane »

I see. So, since there is no ''isolated'' allen wrench, this coil should be not set when monitor is ON, correct?
But how to set it without seeing what we do? In the case if the coil still works, could I put gloves and use the wrench when monitor ON?
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Re: MS8-18A ''H-Size'' Pot broken

Post by PrincessPrinPrin »

Since it's not clear if the ferrite core is intact or not I was suggesting as a first step to get it out of the coil and take a look at its condition. To do this you can use a metal allen wrench (most people already have a set of these). But assuming the coil is fine, you must use a plastic hex tool to adjust it when the monitor is on (metal would alter the magnetic field).
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Re: MS8-18A ''H-Size'' Pot broken

Post by erzane »

I took clear pics. To my eyes it looks to be ok. We can clearly see the exagonal form for the tool. I'll try now to use my ''woody'' allen wrench :D
Image
Image
Not sure but I think those are the fragments from the coil, when the pot inside was in better shape, but still desintegrated as basis, that why it came easily off from the pipe:
Image
Anyway, all plastic hex tool I found aren't really all plastic. They have a plastic parts to isolate hand from metal touch but the end of the tool is in metal. I'm not pretty sure but to my opinion, putting gloves will be the same. I don't find any all ceramic or all plastic hex tool :(
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