K7000 Problem

slots

Active member
Joined
Jan 18, 2009
Messages
1,326
Reaction score
22
Location
Washington, Pennsylvania
This is a K7000 chassis. I recapped and installed a new flyback in it for a friend. He installed it and it has a line about 3" from the top of the screen. Screen is brighter through that area and picture is distorted in that area.
 
Last edited:
Try 50/60 pot.

Can someone explain a little more about this 50/60 Hz pot found on K7000s?

It's not mentioned in the stickies, and search is ineffective ("The following words are either very common, too long, or too short and were not included in your search : 60, Hz, 50")...

I assume it is there for operation on both European 50Hz and US 60Hz power? Is it not seen on other monitor models because they made different models for 50Hz and 60Hz power? Why not just a switch for 50/60Hz; why a pot? I'm not sure what it actually adjusts... the vertical scan rate? Horizontal rate?
 
using the diagram you posted - http://www.wellsgardner.com/pdf/Boar...nd_27_inch.pdf where is the 50 - 60 hz pot located? as i have had this same issue, with the exact k7000 chassis, and couldnt atleast try this method becuase i couldnt locate the 50 - 60 hz pot.

shown here

http://forums.arcade-museum.com/album.php?albumid=489&pictureid=4060

Here is a picture of the pot (this chassis is missing the H. Hold pot). It is just behind and to the left of the H. Hold pot.
 

Attachments

  • K7000.jpg
    K7000.jpg
    101.4 KB · Views: 374
Thx for the response, unfortunately i have a k7000 without a satellite board and adjustments are on the chassis itself, therefore the 50 - 60 hz pot isnt in that location, like i said going from the exact chassis on that diagram (due to the fact that its the exact k7000 chassis that im dealing with) where can i find the 50 - 60 hz pot?
 
Thx for the response, unfortunately i have a k7000 without a satellite board and adjustments are on the chassis itself, therefore the 50 - 60 hz pot isnt in that location, like i said going from the exact chassis on that diagram (due to the fact that its the exact k7000 chassis that im dealing with) where can i find the 50 - 60 hz pot?

Even on a 19" with no remote board, the 50/60hz pot is in the same location. Just snap a pic of your chassis and post it.
 
seems to be alot of mystery surrounding this issue and its really simple. Gonna add this to the sticky if you guys dont mnd.
 
Thanks for pointing out some clarifying documentation. It would seem (to me, based on reading the docs) that it has nothing whatsoever to do with operation on 50 or 60Hz AC power... but instead deals with height adjustment for input signals having vertical frequencies that vary (presumably among different games) between 50 and 60Hz.

Still at a bit of a loss as to why this seems to be the only chassis with this particular adjustment. Perhaps it's just a shortcoming of the design...
 
Thx for the response, unfortunately i have a k7000 without a satellite board and adjustments are on the chassis itself, therefore the 50 - 60 hz pot isnt in that location, like i said going from the exact chassis on that diagram (due to the fact that its the exact k7000 chassis that im dealing with) where can i find the 50 - 60 hz pot?

Some of the early P447 main chassis did not have the 50/60Hz circuit.
 

Attachments

  • untitled.jpg
    untitled.jpg
    92.7 KB · Views: 84
but instead deals with height adjustment for input signals having vertical frequencies that vary (presumably among different games) between 50 and 60Hz.

Exactly....slight differences amongst different games.

Still at a bit of a loss as to why this seems to be the only chassis with this particular adjustment. Perhaps it's just a shortcoming of the design...

I think of it as a bonus adjustment, not a shortcoming in chassis design.
There's been plenty of other chassis that will have a similar problem with certain games and all you can do is get it "close". (often seen as a slight curl at the top) The 50/60Hz pot gives that extra little bit of adjustment.
And even then it doesn't always cure it all.
 
The 50/60 pot will make a world of difference when switching from a Zenith flyback to a regular k7XXX board as well. Felt like killing my machine until I remembered this existed. Then looked here to see if anyone else was having trouble and of course I should have looked here first. LOL.
 
Bumping this thread for a question. I have a K7000 chassis without the remote board, and lacking the 50/60 Hz adjustment pot, and it is having the same issue with a bunch of weird/extra lines at the to of the screen that I cannot adjust out. The PCB has the spot for it, so can I just add the pot (looks like it should be a 200 Ohm?), or does it require adding other components as well?
 
Back
Top Bottom