Monitor colors out of focus (Solved)

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nem
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Re: Monitor colors out of focus

Post by nem »

Asayuki wrote:you don't want to make the situation worse.
How much worse can it get? That's unplayable.
PrincessPrinPrin wrote:Bad yoke.
I have a feeling this is the only real answer in this thread, because of the the fact that everything actually lines up in the center.
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Re: Monitor colors out of focus

Post by PrincessPrinPrin »

Rossyra wrote:Are the rings normally that far back on a WG then?
WG doesn't matter. It's the tube manufacturer (Orion) that installed the ring assembly and yes, on Orion tubes the rings aren't very close to the yoke. Here's one of my Orion tubes (same JLL family as the one posted above):

Image

And in any case it's easy to see that the rings never moved along the neck: if you loosen the clamp the bonding compound will break and if the ring assembly were originally in a different position the glass cloth tape wouldn't be right under it now:

Image

So the rings may have been rotated from the factory position but the whole assembly has always been there.

What I would do before trying anything else is measure the yoke (resistance and if possible also inductance) and see if there is a short.
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Re: Monitor colors out of focus

Post by PikkaKO »

PrincessPrinPrin wrote:And in any case it's easy to see that the rings never moved along the neck: if you loosen the clamp the bonding compound will break and if the ring assembly were originally in a different position the glass cloth tape wouldn't be right under it now
Yea I tried moving the covergence rings without any luck.
nem wrote:
PrincessPrinPrin wrote:Bad yoke.
I have a feeling this is the only real answer in this thread, because of the the fact that everything actually lines up in the center.
Yea I also have a feeling that it's a bad yoke.
PrincessPrinPrin wrote:What I would do before trying anything else is measure the yoke (resistance and if possible also inductance) and see if there is a short.
I don't have a multimeter on me right now but if it turns out to be a short, I wonder if fixing it is so much work that it's much easier to just change the yoke?
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Re: Monitor colors out of focus

Post by Asayuki »

nem wrote:How much worse can it get? That's unplayable.
He could break the neck by accident while trying to push the block towards the yoke...
My 15kHz cabinet Peplos will never power up, with any item, and I am quite proud of that.
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Re: Monitor colors out of focus

Post by PrincessPrinPrin »

PikkaKO wrote:I don't have a multimeter on me right now but if it turns out to be a short, I wonder if fixing it is so much work that it's much easier to just change the yoke?
If this was a small neck (29mm) tube I would have replied that the easiest thing is to replace the tube altogether as practically any TV tube will have a yoke compatible with the WG K7000 chassis. However, what you have is a minineck tube (22.5mm) and Orion is pretty much the only maker of 20" tubes with a minineck (like the one I posted above for example) so finding one in a TV may not be easy for you. And the same holds for a replacement yoke: unless you already have one where are you going to get it from?

Better measure the yoke first and if that's OK then try adjusting the rings. If all fails look for replacements.
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Re: Monitor colors out of focus

Post by Asure »

OP still alive? What were the measured yoke resistances? (I'm a curious basterd..)
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Re: Monitor colors out of focus

Post by PikkaKO »

Asure wrote:OP still alive? What were the measured yoke resistances? (I'm a curious basterd..)
Still alive :D The problem is I don't live in the same city as the cabinet so I only get to test it when I'm there (~once a month). Now I'm here and I can measure it tomorrow probably. Any tips on how and where to measure the resistances? (Maybe this guide http://forums.arcade-museum.com/showthread.php?t=224939 ?)
Edit: Ah found the forum's own guide also (http://forum.arcadeotaku.com/viewtopic.php?f=4&t=181) :awe:

Also found this http://forums.arcade-museum.com/showthread.php?t=134818. For example there's a part about convergence issues caused by the flyback.
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Re: Monitor colors out of focus

Post by Asure »

There are four wires coming from the yoke.
Unplug the connector from the main board and stick the multimeter into the connector leading to the tube. Set it to ohms, 100 should be fine.
One pair of wires should read a bit lower than the other.

Some examples are 6.9ohm or 19.0 ohm and so on. I am not sure what your values should be exactly.
Odd low values would be below 4-5 ohms.

Discharge the monitor before working on it offcourse.
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Re: Monitor colors out of focus

Post by PrincessPrinPrin »

Asure wrote: Odd low values would be below 4-5 ohms.
Actually, normal values are well below that (for the H yoke).
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Re: Monitor colors out of focus

Post by PikkaKO »

Okay, measured the resistances now.

Horizontal (between red and blue): 4.4 Ohms
Vertical (between green and yellow): 14.3 Ohms
PrincessPrinPrin wrote:
Asure wrote: Odd low values would be below 4-5 ohms.
Actually, normal values are well below that (for the H yoke).
So is this too much then?
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Re: Monitor colors out of focus

Post by PrincessPrinPrin »

Yes, that's what I thought: horizontal yoke is damaged.

The horizontal yoke is made of two identical windings wired in parallel so the total resistance is half a single winding. Two windings of 4.4ohm each in parallel give 2.2ohm and that's the correct resistance of a WG K7000 H yoke. This means that one of the windings is interrupted (broken, corroded, burned...) and you only have the other left which cannot deflect correctly alone.

Replace the yoke or the whole tube (latter is much easier).
Last edited by PrincessPrinPrin on November 13th, 2016, 10:46 am, edited 2 times in total.
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Re: Monitor colors out of focus

Post by PrincessPrinPrin »

sorry double post
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Re: Monitor colors out of focus

Post by PikkaKO »

PrincessPrinPrin wrote:Yes, that's what I thought: horizontal yoke is damaged.

The horizontal yoke is made of two identical windings wired in parallel so the total resistance is half a single winding. Two windings of 4.4ohm each in parallel give 2.2ohm and that's the correct resistance of a WG K7000 tube. This means that one of the windings is interrupted (broken, corroded, burned...) and you only have the other left which cannot deflect correctly alone.

Replace the yoke or the whole tube (latter is much easier).
Alright thanks for the info! As you said earlier, it is probably not easy to find these tubes. Any idea where to start looking from?
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Re: Monitor colors out of focus

Post by PrincessPrinPrin »

That's going to be a frustrating search. I would get hold of the other k7000 neckboard (very easy to find if you don't mind buying it from the US) and then replace the tube with pretty much any from a donor TV.

Or if you feel like replacing the yoke, then a replacement (from a smaller than 20" tube) is easy to find (I could give you one for free).
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Re: Monitor colors out of focus

Post by PikkaKO »

PrincessPrinPrin wrote:Or if you feel like replacing the yoke, then a replacement (from a smaller than 20" tube) is easy to find (I could give you one for free).
So is it basically the same operation as the guy does in this video? (heating the yoke until the glue is melted and carefully pulls it out)
https://www.youtube.com/watch?v=O5xxoVD1JOw
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Re: Monitor colors out of focus

Post by PrincessPrinPrin »

No, your yoke will come off much more easily. You just have to unscrew the clamp on the neck, remove the 3-4 rubber wedges around the yoke rim and it will come off with a twist and pull action. The video doesn't show all the work needed to instal the new yoke and rings to have correct geometry, purity and convergence.
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Re: Monitor colors out of focus

Post by Asure »

As a last resort, you should also inspect the yoke soldering taps on the yoke itself. The copper windings end up on some pins and then the cables are soldered onto them. Check the connections for both the red & blue wires. Perhaps wiggle a little at them with the multimeter connected. It could be a loose joint there somewhere on the tap(s).

Also, the red HV wire is resting on part of the yoke. There could be dust or crud, or even a visible break in there. check that as well. (Again, discharge the tube before handling hv stuff.)

Re-yoking a tube is a lot of work, and there's a little more risk involved with the tube running & adjusting stuff. Still, it can be done.

Basically everything is explained in this really great video:
From this part around 7:23 if you slide on the good yoke & rings back etc.
Best to watch the whole video, it's really great with picture in picture and all :)

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Re: Monitor colors out of focus

Post by PikkaKO »

Yea was just watching this video! Seems very thorough. Maybe I'll give it a shot over the Christmas holiday 8-)
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Re: Monitor colors out of focus

Post by PrincessPrinPrin »

Did you manage to remove the yoke? Because I have found this yoke that should work fine:


Image
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Re: Monitor colors out of focus

Post by PikkaKO »

PrincessPrinPrin wrote:Did you manage to remove the yoke? Because I have found this yoke that should work fine:


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Looks good!

Next time I can work the monitor is in December at some point (probably near Christmas) so haven't had the chance to try and take it out yet. So this yoke is compatible with my minineck tube?
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