WG K4900 - Color issue upon tilt and vertical size issue

bszarek001

Member
Joined
Jul 31, 2017
Messages
70
Reaction score
4
Location
Loveland, Ohio
WG K4900 - Color issue upon tilt and vertical size issue

Hi Everyone,

Looking for a little assistance. This is for the Super Pac Man table I've been working on. I dug through the forum and couldn't find exactly this issue.

I just purchased a working replacement chassis and recapped the whole thing. It has a 5-cap neck board and 3 caps on the PCB. Forgive me, as i'm just learning, so if it's something simple, go easy on me. LOL

First, the color issue. Occasionally when I open the lid on my cocktail cabinet to about a 15-20 degree angle the color will be fine, but as I close it, the color in the lower right corner will become more faded. I've sprayed all of the pots with contact solution. It seems to be working correctly for now, but as you all know, we have to open these things up from time to time, so I would like to know why this is doing this? Does it need to be degaussed?

Second issue is the horizontal width adjustment. I have the image as large as it can get, and I try to move the image on the horizontal, but if i go too far to the right (P1 position), it will go to waves. The furthest I can get is about 1/2" from the right border before it craps out on me. Any thoughts on how I might be able to correct this? I've read the K4900 manual and I see the horizontal raster shift jumpers, but I've not done this before. Would this be the issue, and if so, which jumper should I use?

Thanks everyone!
 

Attachments

  • Photo Aug 17, 8 40 40 AM.jpg
    Photo Aug 17, 8 40 40 AM.jpg
    541.1 KB · Views: 17
  • Photo Aug 17, 8 45 05 AM.jpg
    Photo Aug 17, 8 45 05 AM.jpg
    465.1 KB · Views: 11
  • Photo Aug 17, 9 01 57 AM.jpg
    Photo Aug 17, 9 01 57 AM.jpg
    538.7 KB · Views: 11
degaussing YES.

try the jumpers and they are in the back right side of the chassis and will have three pins and see where its at.
 
Color issue resolved - still have horizontal width issue

Thanks security --- I figured out what was wrong with the color in the lower right corner. The stupid ground wire was dangling too close to the power brick. I tied that up and now the color is bright and perfect.

The horizontal is still an issue though. I've messed with all 5 pots on the PCB and can't get it any closer. This is what i see on my chassis. The only thing i haven't messed with is the "horizontal width coil." Is that the black chess piece looking component with the copper coil wrapped around it? If so, how do I adjust it? It seems like an immovable object when I tried.

Thanks!

(and i have no idea why the forum is rotating these pictures...sorry).
 

Attachments

  • IMG_4810.jpg
    IMG_4810.jpg
    233.7 KB · Views: 6
  • IMG_4811.jpg
    IMG_4811.jpg
    309.3 KB · Views: 8
  • IMG_4812.jpg
    IMG_4812.jpg
    245 KB · Views: 8
yes that is the width coil. you need non conductive tool that goes down the center of it and you screw the ferrite slug up or down to change the size of the picture, but remember if its seized don't force it because it will break and you won't find a replacement easily. most monitor width coils only adjust the picture size 1/4 to 1/2 inch at the most. it was common on those k4900 you live with certain imperfections in size and position you will find with enough reading here.

BTW: k4900 have yoke incompatibility issues also you will notice which means you can't put just any k4900 on any k4900 yoke. (yours doesn't look like the case here but just to keep in mind for the future projects).
 
Thanks for the help. I have to find something non-conductive to use. I will give it a shot. I didn't realize it was adjusted internally -- which is strange when everything else on the board is adjusted via pots and jumpers.

I'll let you know how it works! Thanks again.

yes that is the width coil. you need non conductive tool that goes down the center of it and you screw the ferrite slug up or down to change the size of the picture, but remember if its seized don't force it because it will break and you won't find a replacement easily. most monitor width coils only adjust the picture size 1/4 to 1/2 inch at the most. it was common on those k4900 you live with certain imperfections in size and position you will find with enough reading here.

BTW: k4900 have yoke incompatibility issues also you will notice which means you can't put just any k4900 on any k4900 yoke. (yours doesn't look like the case here but just to keep in mind for the future projects).
 
i stock all the non conductive tools if you need anything.
 
So my father, in his infinite wisdom and hoarding, when he gave me his electronics tool kit,
happened to have not one but TWO plastic hex drivers for use in the horizontal width coil.
It appears that (and this could be just me) they use the term vertical and horizontal interchangeably sometimes in these diagrams.

At any rate, I tweaked the width coil and it stretched the screen out perfectly from joystick to joystick.. obviously doesn't help me with this issue, but it did clean up the image a bit anyway.

Any other thoughts as to what might stretch the screen out vertically (in this instance) other than the vertical pot? Like i said, I can only go so far, then it starts going squirrely on me (even though I have more room to turn the pot). If this is as far as it can go, it's certainly not bad and definitely playable. Just figured I'd ask -- can't hurt. Thanks again!

yes that is the width coil. you need non conductive tool that goes down the center of it and you screw the ferrite slug up or down to change the size of the picture, but remember if its seized don't force it because it will break and you won't find a replacement easily. most monitor width coils only adjust the picture size 1/4 to 1/2 inch at the most. it was common on those k4900 you live with certain imperfections in size and position you will find with enough reading here.

BTW: k4900 have yoke incompatibility issues also you will notice which means you can't put just any k4900 on any k4900 yoke. (yours doesn't look like the case here but just to keep in mind for the future projects).
 
Back
Top Bottom