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 Post subject: Convergence Help Mitsubishi XC3725C
PostPosted: Sun Sep 08, 2019 2:30 am 


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Joined: 27 Apr 2015
Posts: 644
Location: Bellingham, WA
I am getting horizontal and vertical Red drift on My Mitsu XC3725C.

The total adjustment procedures including service are on page 60 of the service manual (thanks Retro RGB)

https://cdn.retrorgb.com/assets/monitor ... -3725C.pdf

I could not find a convergence option in the adjustment procedures.

I feel comfortable at this point adjusting the yoke rings and focus but I don't understand if the V focus and H focus will help with convergence.

The yoke rings and focus rings are held factory by a hard yellow adhesive.

Image
Image

Unlike most yokes, This one has finger notches and a thick glue outline to easily adjust and get back to factory.

Hopefully someone could shed the basics of whether the H and V focus will help with my convergence issue.

Also I counted 7 ring adjustments (cogs) on the yoke and would love to know what they do and whether or not to touch them to resolve my issue. Is there a typical order to these yoke adjustments?

If someone (especially XGA) could help lead me down the path of troubleshooting this I would be very grateful.

Bonus question: do I need an oscilloscope to do this adjustment?

High res photos is in spoiler

Spoiler: show
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 Post subject: Re: Convergence Help Mitsubishi XC3725C
PostPosted: Mon Sep 09, 2019 3:36 am 


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Joined: 24 Jul 2016
Posts: 247
Convergence is the alignment of the R ,G and B beams. Focus adjustment, whether H-, V- or both, is exactly that - or how sharp your image is. The two are separate, as a rule. And I say rule as i'm sure someone will find an exception, and I haven't actually read the service manual.

EDIT: post up some photos of the convergence now, if you would :)

If there's no other convergence adjustments available, you're going to need to adjust the yoke and use the rings. Mark everything very carefully before you start, and again when you're done - and make sure you have a way to fix the rings in place once finished, ordinary silicone won't grip old rings well. Damn i wish earlier sets used the lock-release mechs found on later sets to clamp thingsi n place easily.

Manufacturers include a lot of heiroglyphics in the Service Manuals that won't make sense until you actually try to adjust things, and i would strongly recommend finding a throwaway set and practicing on that first, that way you know what to expect when you move things, and you'll be able to decode whatever is in the service manual more effectively.

And before any of this, make sure you know how to discharge the tube and how to be safe around live equipment.

This is a nice video to get you started - https://www.youtube.com/watch?v=Gmrrf5hiYQI


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 Post subject: Re: Convergence Help Mitsubishi XC3725C
PostPosted: Mon Sep 09, 2019 3:59 am 


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Joined: 27 Apr 2015
Posts: 644
Location: Bellingham, WA
buttersoft wrote:
Convergence is the alignment of the R ,G and B beams. Focus adjustment, whether H-, V- or both, is exactly that - or how sharp your image is. The two are separate, as a rule. And I say rule as i'm sure someone will find an exception, and I haven't actually read the service manual.

EDIT: post up some photos of the convergence now, if you would :)

If there's no other convergence adjustments available, you're going to need to adjust the yoke and use the rings. Mark everything very carefully before you start, and again when you're done - and make sure you have a way to fix the rings in place once finished, ordinary silicone won't grip old rings well. Damn i wish earlier sets used the lock-release mechs found on later sets to clamp thingsi n place easily.

Manufacturers include a lot of heiroglyphics in the Service Manuals that won't make sense until you actually try to adjust things, and i would strongly recommend finding a throwaway set and practicing on that first, that way you know what to expect when you move things, and you'll be able to decode whatever is in the service manual more effectively.

And before any of this, make sure you know how to discharge the tube and how to be safe around live equipment.

This is a nice video to get you started - https://www.youtube.com/watch?v=Gmrrf5hiYQI


Why would I discharge the tube unless I disconnect the anode cap?

I have linesman gloves and plan on adjusting with the picture on. discharging would be redundant as I would recharging for live adjustment.

That video was awesome though and I hope it doesn't come to wedges in the neck-board.
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 Post subject: Re: Convergence Help Mitsubishi XC3725C
PostPosted: Mon Sep 09, 2019 4:24 am 



Joined: 19 Oct 2013
Posts: 552
Location: Riverside, CA
I second practice on a junker monitor first. And to be meticulous about marking your starting point.

But yeah, you can't adjust these without it being on. I mean, you can but you wouldn't know what you've accomplished. You should however have a solid idea of what not to touch before doing so.


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 Post subject: Re: Convergence Help Mitsubishi XC3725C
PostPosted: Mon Sep 09, 2019 7:25 pm 


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Posts: 545
Location: San Jose, CA
You do not need to discharge the monitor, that is correct.

The ring order can vary between manufacturers but the de-facto standard order, starting from the bell (front) of the tube, is this:

2-pole magnet pair: purity (please do not touch these if you have no cause!)
4-pole magnet pair: red/blue separation and alignment
6-pole magnet pair: magenta/green separation and alignment

Before doing any of this, it is good to make sure you have set the focus voltage on the flyback. This is achieved by turning the knob and looking at the screen.

For static convergence, rotating the rings within a pair in opposite directions changes the distance between the color pairs, while rotating the rings in unison changes the beam position. Think of these as manipulating the two components of polar coordinates.

You first want to use the 4-pole pair to align red and blue together, such that they form a magenta tone (red + blue). You should not see red or blue fringes on the sides of the combined colors. You will have to get a "feel" for manipulating the distance and positioning.

You then want to us the 6-pole pair to align your newly formed magenta with the green color, until you have formed a decent white.

If things are not great on the edges but are nice in the center, remember that it's all a balancing act between the elements here, so some iterative work is required.

These rings only help for static convergence (across the whole screen, relatively uniformly). For corner work, some monitors have adjustments, but often some mu-metal strips are what you need for the corners.

(forgive me if the pole count is reversed, I do not remember!)
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 Post subject: Re: Convergence Help Mitsubishi XC3725C
PostPosted: Tue Sep 10, 2019 3:18 am 


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We haven't even seen a picture yet! If he's trying to adjust a dynamic convergence issue in one corner, we're all steering him wrong :)


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 Post subject: Re: Convergence Help Mitsubishi XC3725C
PostPosted: Wed Sep 11, 2019 4:33 am 


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Location: Bellingham, WA
buttersoft wrote:
We haven't even seen a picture yet! If he's trying to adjust a dynamic convergence issue in one corner, we're all steering him wrong :)


It does seem like a stronger problem in the lower right hand corner than anywhere else in the screen. And the screen is Non-tateable but I have played it Vertical many times with the help of a burly friend.

Here is the Half Life 2 Dreamcast Loading Screen.

I see red bleed above, below and to the right side of the orange border?

Image


Here is the Test Suite image

Image

It is not as bad during gameplay, but I swear it's worse on 480p or higher res images.

Image

Here is the lower right corner of the screen where it seems the worst

Image

But here is the center of the grid, where it seems more mild closeup:

Image

I am gonna shoot for slight Blue green convergence. I may have caused it from my tate.
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 Post subject: Re: Convergence Help Mitsubishi XC3725C
PostPosted: Sun Sep 15, 2019 2:09 pm 


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Joined: 02 Oct 2010
Posts: 3117
Location: Ireland
I have the 3730C and the bottom left corner is blurry in 480p and above but looks fine in 240p and 480i. The geometry is also way worse the higher res I feed it.

I'd be interested to know how you got on with the adjustments.
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