6100 Focus

Airdorn

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Donor 5 years: 2014, 2019, 2022-2024
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Hi there.

Working on a WG6100 from an old Tempest. This monitor had several problems but all have been resolved except for one: the focus pot on the HV has no effect. The game will come up well focused but after a few minutes the focus goes south and everything is a blur. After a while it will return to a reasonable state, but it may revert to unfocused later. Very strange.

* Brightness control works fine.
* Cap kit done
* Run in a working Space Duel
* Swapped deflection boards and no change.

I have access to a couple other wg6100's so I can swap major parts as needed. :)

The flyback was replaced within the last couple of months and the works appears solid.

The focus pin inside the neckboard connector appears intact.

Any tips would be appreciated!
 
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I would think this is the focus wire connection not being rock solid in some fashion from the flyback

Several different locations this could be happening. The focus wire has a connection covered by a rubber boot (on the back side of the white focus block), it goes through the 3 pin molex connector (either side could be bad or the pins), the focus wire could be broken loose where it solders into the neck connector, the neck connector could be bad, and finally the pin on the neck of the tube could be broken off.

The worst of those is the pin broken on the tube as they are almost impossible to find replacements for but you can sometimes use electrical epoxy as a fix.

Don't go poking around the white focus or the red G2 wire while the monitor is on. The G2 is anywhere from 0 to 1.5kv and focus is right around 6kv.
 
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One other thing to check is the G2 / Focus 2-wire connector exiting the HV Cage (P901 / J901shown on the schematic). I've had several instances where the connection deteriorates from repeated wiggling and connect / disconnect cycles. Look at the female terminals and see if the gaps are opened up. If so, you can carefully squeeze them back together with a small pair of needle nose pliers. The long-term solution is to replace both the male and female pins.Screenshot 2024-12-26 at 8.54.19 AM.pngScreenshot 2024-12-26 at 8.57.56 AM.png
 
Yup, sure enough... no continuity between that plug and the pin of the neck plug. Thanks for the info!
 
Gothgirl nailed it first. I'd forgotten how simple that focus arrangement was. I was overthinking something in the HV area, etc. :)

Problem is inside the tube plug itself on the neck board. I'm opening that up here in a few mins to investigate.

As always, awesome community here!
 
Giving credit where credit is due - that connector was called out in Post #3 by @bakerhillpins and I overlooked it - and thus mentioned it again. All's well that ends though - hope that by repairing and / or re-working those terminals, you are rewarded with stable focus.

Nah the pics helped... also, when several people pile on with essentially the same answer, you can rest assured that it's probably the right one. ;)
 
Giving credit where credit is due - that connector was called out in Post #3 by @bakerhillpins and I overlooked it - and thus mentioned it again. All's well that ends though - hope that by repairing and / or re-working those terminals, you are rewarded with stable focus.

Everybody contributed.. no harm no foul. At least from my end..

I detailed the entire pathway because many don't think there are so many opportunities for the problem.
 
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