Convergence or linearity issue

Cliff Clavin

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Hi guys,

I just received an Ok Baby candy cab and discovered the following issue as seen in the pic. I have adjust the vertical linearity to its max position which improved the picture but did not fix it entirely. I believe convergence is when things don't always line up so I am guessing this is more of a linearity problem....

Also noticed that the horizontal size pot on the remote does not do anything at all to the picture....Not sure if that is related to the linearity issue or if that is due to something else entirely.

I read a post where they said cap kits for candy cabs were hard to find which further increased my stress level....

Any help for someone whose technical skills are......well lacking would be putting it politely??.....Are there any other settings that I can adjust that would help my cause??

thanks for any comments....

C.
 

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You have two problems here. A horizontal linearity problem, because the width of the screen is not consistent, and a pincushion problem because the sides of the image are curved and not straight.

Tri-sync monitors often come with a linearity cap suited for 31khz. It can often be fixed (or at least greatly improved) by adding a switch and a capacitor so you can switch between suitable capacitors for both 15khz and 31khz modes.
 
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I seem to remember on another machine I had that it had a setting on the monitor board for 15 or 31....Is that something that I should look for or is it only present on certain monitors?

Hewitson,

Thanks for the info, if the linearity is fixed, would the pincushion issue be that noticeable? Any further info you can give me would be great......

Edit: Ok I found the option of 15 or 24 on the monitor board....The jumper (or molex plug) was correctly set on the 15 setting....so at least that is confirmed.....
 
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A switch to change between frequencies is only present on certain dual/tri sync monitors, some of them do it automatically.

I see no reason why correcting the linearity would have any effect on the pincushion. I actually think you'll find the linearity is working as it should be, it often leaves a lot to be desired when one of these tri sync chassis is running in 15khz mode.. Are you able to provide a model number for this chassis?
 
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its actually a dual sync monitor, no 31, just 15 and 24....will open up the cab and see if I can find the monitor and chassis type....
 
A switch to change between frequencies is only present on certain dual/tri sync monitors, some of them do it automatically.

I see no reason why correcting the linearity would have any effect on the pincushion. I actually think you'll find the linearity is working as it should be, it often leaves a lot to be desired when one of these tri sync chassis is running in 15khz mode.. Are you able to provide a model number for this chassis?

Ugh; not what I wanted to hear at all. I have a tri-sync chassis with linearity issues (I think) and I run it in 15khz mode quite a lot.
 
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A switch to change between frequencies is only present on certain dual/tri sync monitors, some of them do it automatically.

I see no reason why correcting the linearity would have any effect on the pincushion. I actually think you'll find the linearity is working as it should be, it often leaves a lot to be desired when one of these tri sync chassis is running in 15khz mode.. Are you able to provide a model number for this chassis?

I could not find much info on the chassis. The best I could find was:

MSU1FHH09
96402T

Not sure if this means anything or not....I have included a few pics just in case it could be of use....

Lastly, can anyone comment on why the horizontal pot would not have any effect on the image??

thanks fellas...

C.
 

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That's good news. You should have pots for both h.linearity and pincushion (SPC) as seen in this picture:

MS9chassispots.jpg
 
That's good news. You should have pots for both h.linearity and pincushion (SPC) as seen in this picture:

MS9chassispots.jpg


Hewitson,

Thanks for the good info!! I had messed with the v lin and thought it had improved things a bit but I couldn't read the other adjustments on the chassis....I started moving them and asked the wife if it was making any difference. and she of course replied no changes...

I will try again adjusting the pots and will have fingers crossed...
unfortunately I am heading off to a kids movie now....grrrrrr, real life interfering with the really important things.....

Thanks again!
 
Is this a linearity problem?

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Ok, had some time to play....

First, I adjusted the jumper from CN507 to CN506....This is supposed to set the horizontal size limit to wide from normal....This seemed to have no discernible effect....still no change in picture when adjusting the horizontal size on the remote board. rats......

Attempted to adjust the SPC15 and no noticeable change (also tried the spc24 just in case, but unsurprisingly, it also had no effect)...

I then tried the H.S. LIN and could not see any change at all.....adjust the V. Lin had a change and I set it where I thought the pic was best... the VS limit also had an effect but it seems like anything to do with horizontal has no effect, save for the horizontal position pot....

Any other ideas??? any other jumpers on the board I should look at??

thanks again.

C.
 
Hewitson (or anyone else...),

I pulled out my phoenix arcade pcb and hooked up a mame machine to see what happens to the monitor image.

The vertical hold was out and adjusting the pot had no effect on the rolling screen.

Can anyone say why the horizontal size pot, the pincushion pot, the vertical hold pot all don't seem to work? Some of these pots are on the remote and others right on the chassis itself.

It seems very odd that adjusting these pots have no discernible effect.

I was thinking about using this machine to run mame for the kids but if the vertical hold can't be fixed then that idea is out.

Thanks for any help and comments.

C.
 
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