Still not a perfect picture after installing cap kit

[DaveJ-UK]

I have just finished installing new caps on my WG K7193.

It works as it did now it's back together, but the problems are still there.

There's a dark patch on the right of the screen as well as a big, bright, white bar at the bottom of the screen on the Windows desktop.

I'm using 640x480 in both Windows (2000, SP4) and MAMEWAH. When I boot up, the Windows desktop rolls a couple of times vertically before holding. The BIOS and other boot screens hold fine as well as MAMEWAH.

All help greatly appreciated as always.

[Ken Layton]

The vertical "foldover" is usually caused by a misadjustment of the "50-60 hz" pot and "Vert size" pot. If that doesn't do it then capacitor C51, which is NOT included in the capkit, should be replaced.

After you get the vertical problems corrected then you center the picture horizontally with the "h pos" control. If the picture is too narrow then adjust the width coil "L1" with a plastic alignment tool.

[MonitorGuru]

Dark patch caused by magnetism.

Get an external degaussing device and use that, and remove any unshielded speakers from that side of the monitor (over or along side or under)

[DaveJ-UK]

Thanks for the replies guys.

The dark patch is indeed caused by the speaker aboive it. I had originally ruled this out because it's only on one side and both speakers have identicle markings. Does this just mean that one speaker is shielded and one is not, even though they are the same brand/model or is the shield faulty?

[JoeB]

there's an easy test..

take the speaker and bring it to the front of the monitor.  If it does funky stuff, then it's not shielded.

You have to be careful with surround sound speakers.  In most cases, only the fronts are shielded.. the back ones are not.  You might have this problem.

[DaveJ-UK]

The speakers were in the cab when I got it - I just wired a stereo amp from a pair of pc speakers to it.

The 2 speakers are above the monitor facing down. The dark patch only appears on one side, as shown in the attached pictures.

Edit: I have removed the unshielded speaker; the dark patch has gone. When I waved it in front of the screen, it went all purpley and green. Although it looked cool, it left two dark patches. I waved it around some more and around the tube itself and got rid of one and the other is now quite faint. Will this disappear with time? I've turned it on and off a couple of times but it doesn't seem to have made a difference.

[dabone]

I've got a 7000 series with the same vertical fold over, where is c51? I'm not seeing it on the PC Board Layout page.


Later,
dabone

[DaveJ-UK]

Adjusting the 50-60Hz pot sorted it for me. I didn't even realise it was there it was so grubby!

It's between the H. Hold and H. Shift pot set back an inch on the left of the main PCB. No idea where C51 is, but there's not that many caps on the board so just wipe the muck away from each of the caps until you find the marking (assuming yours is as dirty as mine is!). Alternatively, download the manual in .pdf format and start hunting, but that's not much fun

[dabone]

Found c51 (right behind the 50/60 hz pot). Mine has a 100ohm resistor soldered in between the board and the - side.

Is this some hack? or did WG send some out like that?


Later,
dabone

[Ken Layton]

C51 is directly behind the 50-60 hz pot. Yes, Wells-Gardner did indeed have some k7000 chassis with odd resistors and capacitors soldered here and there on the board. Don't take them off!