swapping wg7602 neckboard to wg7191

Rabidcat

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I meant wg7648 neckboard on to a wg7191 chassis. If the pins are the same is it ok to use a 19" neckboard with a 25" chassis on a 19" tube?
 
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I meant wg7648 neckboard on to a wg7191 chassis. If the pins are the same is it ok to use a 19" neckboard with a 25" chassis on a 19" tube?

You can try it but I'm thinking the picture will be too big for the 19" tube being the chassis is designed to run on a 25" tube.
 
The pic will be overdriven and not fit the screen. I use a 13" for testing purposes and both 19" and 25" chassis always extend well beyond the edge of the screen. For my purposes it is easier to use the 13" monitor on the bench but I always need to shift to a proper size tube for convergence and symmetry testing.
 
I actually installed the 7191 on the 19" and the picture was too big, that's why I was thinking of trying the 7648 neckboard. Will this have any effect on the size, otherwise I won't bother.
 
I actually installed the 7191 on the 19" and the picture was too big, that's why I was thinking of trying the 7648 neckboard. Will this have any effect on the size, otherwise I won't bother.


The neckboard has no effect on the size. The size is determined by circuitry on the main board. You could compare the schematics between the two and swap out the few components that need changing (the VR is the only thing that comes to mind but there may be more). Doing that and swapping the neckboard should effectively convert your 25" to a 19".
 
So swapping the horizontal coil and vertical size pot would do it?


I doubt either of those components are different. Like I said the VR (voltage regulator) is different. There may be some other components in that circuit as well. I can not get to the schematics from this work computer in order to look.
 
the width coil and cap are both different.
as well as the VR. the vertical IC is also different along with some resisters i don't know witch ones.

all the adjustment pots are all the same between 13"-25" chassis.

Peace
Buffett
 
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the width coil and cap are both diffrent.
as well as the VR. the vertilal ic is also diffrent along with some resisters i dont know witch ones.

all the adjustment pots are all the same between 13"-25" chassis.

Peace
Buffett


The width coil is not different. What cap are you referring to?

I do see an additional cap, C69, on the 25" model. I would guess it is jumpered out on a 19" chassis.
 
IC3 is wired up a little differently as well. Honestly, at this point it would be cheaper to fix your 19" chassis or swap the 25" with a 19".
 
Yeah, this sounds like more work than I want to do. The 4648 works but will eventually shut down completely. If you unplug the monitor or shut the game off and wait a few minutes it will come on again. There is no set time when it shuts down though. Sometimes a few minutes sometimes a couple of hours... frustrating.
 
That just sounds like cold solder joints. Pull the chassis and look over it very closely.

From the component side push down on components and watch from the solder side to see if there is any movement. Start with any large caps, they tend to build up heat quickly and desolder, this is where solder breaks loose first.
 
C38 is a different value
and
C37 can be a different value.

some 25" chassis have 2 poly caps and some only have one. there are some models you can mod to one cap and others you cannot. you need both inveigle caps or it will short out the one to ground when you try to mod the chassis due to being a undocumented factory mod.

and the width coil is a different value between the 19" and the 25"

Peace
Buffett
 
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That just sounds like cold solder joints. Pull the chassis and look over it very closely.

From the component side push down on components and watch from the solder side to see if there is any movement. Start with any large caps, they tend to build up heat quickly and desolder, this is where solder breaks loose first.

I already capped it and touched up any suspicious point so I'm at a loss.
 
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