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Goku127

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Hey,

i have an Overscan Issue on my sanwa monitor. I already did a recap, but it has not helped. Basically even with the smallest H Size and V Size setting, the picture is too large for the screen. And it only gets worse when the Monitor heated up after about 30mins. You can see that a whole line of boxes are missing on the left and right side of the screen, and basically a bit on the top and bottom on the screen. Any idea what the Problem could be ?

Thanks in advance
Goku
 

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Goku127

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@nem First of all, thanks for your fast reply. Actually if I think about it, some arcing/ticking noise is happening when the screen is black/mostly black. But I have two questions since I'm kind of a cheap ass: 1. Why does this effect get worse when the Monitor heats up ? 2. Is there any possibility to repair the Flyback?

Thanks in advance
Goku
 

nem

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1. Why does this effect get worse when the Monitor heats up ? 2. Is there any possibility to repair the Flyback?

There are components inside the flyback that can start malfunctioning under stress.

It's a sealed unit. You disassemble it, you break it.
 

Mukuro_W

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Its the Flyback wich start to fail, usually those loose power and the piscture stratch horizontally with sometimes pincushion issues..
 

Goku127

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@Mukuro_W @nem thanks for your fast replies. So this Picture which I took right after turning on the monitor, would also underline your assumption that it's the Flyback ?
 

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Mukuro_W

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On 21e31s you will not find a H. Driver transfotmer in the H stage because it is on the yoke itself! When you have a weirdo bigger screen horizontally alongside a pictushion issue you can go straight to replace the Flyback , The H. out transistor often fail alongside with a fuse resistor due to an error in project, basically on first Rev it is not enough powerfull HOT, in this case you have a vertical line at center on the screen or just nothing on screen, a 200w rated transistor one will going to fix this issue and or at least cure this. 2sc5612 or 2sc5144 are both better than the one wich is on first chassis revision.
 
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Goku127

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Mukuro_W

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The Flyback on eBay show the correct model number BUT is not the original one, it is just a repro version, for sure you have to add a resistor, talk with him, he will give you more info if its flyback works then you have your chassis fixed.
In the past I had to replace some flybacks for 21e31s with ones from HR , they also need a mod with a resistor due to broken the protection of the chassis, Those HR worked well! Now the ones on eBay are the only ones still available that I know. Good luck!
 
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nem

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it is just a repro version, for sure you have to add a resistor

With the flybacks from Tecknoservice, there's no resistor change. However, you have to move a jumper.

tecknoservice_29e31s_flyback.jpg


I'm going to order a flyback and see if it's any good. I have a 29e31s chassis with the pincushion issue.

In the past I had to replace some flybacks for 21e31s with ones from HR , they also need a mod with a resistor due to broken the protection of the chassis, Those HR worked well!

Do you remember what resistor you used?

I used a 56k ohm and the HR Diemen flyback works and has worked just fine for over two years, but there's this wavyness in the image in a small area in the center of the screen every now and then. I'm positive it's due to flyback. I'm just wondering if I could get rid of it with a slightly different resistor.

Maybe I'll try putting a variable resistor there.
 

Mukuro_W

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I do not know what t you mea for "wavyness" , the resistor should be 68k but for some reason in most case lower the walue was needed, you can try a higher value and you can try the HV pot just move it slowly just a little bit and see what happen.
This wavyness wich you mentioned was present from the first time you have swapped the flyback? This increase in a full white screen? Or if you try to turn up the G2 pot?
 
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nem

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I do not know what t you mea for "wavyness"

Like if I have text on the screen, it starts juddering. Hard to explain. I can try to take a video of it on the weekend.

I originally tried the 68k resistor, but it made the picture too big.

This wavyness wich you mentioned was present from the first time you have swapped the flyback? This increase in a full white screen? Or if you try to turn up the G2 pot?

It's definitely related to the flyback. I haven't noticed it gets any better or worse depending on the brightness.
 

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I just installed a new flyback from Tecknoservice and although my picture is back it looks a bit dark. Adjusting Screen and Sub contrast results in the CRT going into protection state whenever there is a bright image on screen. I have to turn off the CRT to reset the fail save protection.
Text on screen looks really weird, it's somehow shaky en blocky, also I notice a block of horizontal lines in the bottom left corner of the screen. If I adjust sub. contrast the image and text cleans up nicely, but as soon there is a very bright image in the game it trips the fail save again. I did not have these issues with my original flyback.
 

Mukuro_W

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Talk with Teknoservice , most likely he is aware of this issue and maybe have a solution.
 

nem

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I ordered the Tecknoservice flyback too. I will be extremely disappointed if the picture quality isn't as good as with the original flyback considering how expensive these replacements are. The HR Diemen one was half price.

I should receive mine next week.
 

Spunkworks

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Well, VR401 (pot on the left of flyback) solved most my issues. It's for high voltage and i set it to center(ish) and my fail save issues are solved. I can now adjust brightness without the chassis going into fail save mode.
Most of my shaky and blocky text is gone. However, i do still have weird blocks of horizontal lines on the bottom left of my screen, which i didn't have with the original flyback. For shits and giggles, i'll reseat my original flyback and see if that solves it.

Does anyone know if there is a test suite available for Naomi?
 
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Spunkworks

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I ordered the Tecknoservice flyback too. I will be extremely disappointed if the picture quality isn't as good as with the original flyback considering how expensive these replacements are. The HR Diemen one was half price.

I should receive mine next week.
Yeah, will be interesting to see your results.
BTW, you need to cut the bottom plastic clips from the flyback, or it will not fit. I guess this will void its warranty as well.
 
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