Sanwa 29E31 Overscan issue

[Goku127]

@nem man you are fast with your replies. If you are already on the forum, maybe any other tips for the first start? What about the potentiometers? On the flyback itself an on the whole board?

Thanks in advance
Goku

 

[Goku127]

And, which purpose has the second of the three potentiometers on the flyback? It isn't labeled

 

[nem]

The second pot would be used on a dual focus tube. It's not used on the Sanwa.

I wouldn't worry about the pots. Plug it in and see what happens.

 

[Goku127]

Tried it with an 56k resistor and the image is too big @nem would you try to put in the 47k or go straight back to the old 33k?

 

[Goku127]

Of course this picture is taken while the h and v size pots are turned to a minimum

 

[Goku127]

This is how it looks with 47k still too large

 

[Goku127]

Now the 33k resistor. Started with a really tiny hourglass picture and while trying to adjust the size it started "wheezing" ? . Any Tipps or should I just try in-between the 33k and the 47k resistor.

 

[nem]

Horizontal and vertical size pots are at minimum?

I would put the 47k resistor in and then turn up HV slightly. The HV pot is likely under a mountain of glue.

 

[Goku127]

Yes they are. I disassembled the potentiometer unit just to make sure they all are functioning correctly. And they do. So turning up the hv voltage would shrink the picture? Or get the corners more in? And how do I know when to stop turning it up?

 

[nem]

Higher HV will shrink the image. See what happens if you turn it a bit.

It's odd that the image is so much larger on your chassis that mine. I replaced three chassis with the HR Diemen flyback and the 56k resistor and didn't run into size issues with any of them.

 

[Goku127]

This is the best it would get while the hv Potentiometer was cranked at max. At the edges there is still missing one block at either side. Seems to be as bad as the original Flyback, but that one would change its behavior while getting warmer.
Not sure what to do next. Maybe I'm going to put a potentiometer as the resistor so I could change the resistance on the fly. But what is that wheezing I came across while trying the old 33k resistor?

 

[nem]

I don't know, I never encountered issues such as yours. Maybe there's something else wrong with your chassis.

 

[Goku127]

Maybe @Mukuro_W has any advice?

 

[Goku127]

So I put a potentiometer in series with the old 33k resistor and got it to the point where the corners were in the picture, but in the middle there was still an indentation so it was still hourglassy. But with really low resistor values I noticed that the illuminated part of the screen was bigger than the picture size (the grey part) is that normal?

 

[nem]

That's normal. Turn down brightness and / or the screen pot.

Can't you get rid off the hourglass with the pincushion adjustment?

 

[Goku127]

I have tried to change the pincushion setting as well. Basically the first picture is the lowest setting on the pot, the middle one is where the corners got more in, while the last one is the max setting at which the corners started to get wavy as well.

 

[Goku127]

I took a look at the service manual to see what might be the corporate of the problem. I noticed that H Size Control and Distortion Control had a part number listed as Q424~Q431. While Q424 is an iC that is listed in the service manual, Q431 nor something in between does exist. Any idea on that?

 

[InitialNik]

Hola, tengo el mismo problema, con Tecknoservice flyback instalado. No se como solucionar este problema.