Help Monitor Eygo (Wey Ya) 820h (57705) no pincushion to adjust

[m.andrade1]

Hello Guys
Anyone know how to adjust "pincushion" on this chassis, it doesnt have any regulation for this,  any ideias or some kind of hack/modification to allow this adjust.
Bellow some photos to show you guys the chassis and som snaps of the game, any help or suggest with be very apreciate !

[grantspain]

original crt/chassis combi or did you just install this onto the crt?

[m.andrade1]

Hello grantspain
Thanks for your reply, i bought this cab with a good deal, and pretend to restore it, and put a groovymame setup with a vertical orientation on it, but before have to solve this pincushion issue, that have no solution without the pot to adjust, do you think have some modification or any ideas how to minimize or fix this.
Thanks Marcos

[grantspain]

most chassis i have seen without picushion correction pots tend to have a particular type deflection,the type with big metal wings
i would suggest getting the correct chassis to match your tube

[m.andrade1]

Hello Grantspain
Thanks again for helping me !
So i read the ohms on my yoke, it reads : Vertical 2.5ohms / Horizontal 53.6ohms
On the Chassis, have a label showing: VR 56 / HR 2.0  and another information i dont have idea what it is: 120mh and 1.95mh
Do you think this little diference are causing the pincushion problem ?
Any other ideia for a modification on the board or any other thing to minimize the problem this issue.

Thanks
Marcos

[grantspain]

the impedance matches,the other reading is inductance and you need an inductance meter to read that
it can affect things like pincushion but in my opinion it will be down to the deflection yoke

i am guessing that there is a version of this chassis that has a picushion control circuit

[m.andrade1]

Hello Grandspain
Do you think the Wey-Ya still sells it,  i saw some on Aliexpress like this one:
http://pt.aliexpress.com/item/14-21-inch-CGA-Wei-Ya-chassis-for-CGA-arcade-game-machine-arcade-cabinet-Arcade-Parts/526650422.html?spm=2114.42010308.4.88.54G7io
Itīs very similar of mine, but cannot see any "pincushion" pot on that board too.
Can you recomend one for me?

Thanks a lot
Marcos