K4600 Deflection Yoke Wiring

[jcosper]

I recently acquired a sad K4600 with P297 interface board. It has many issues (triple image, missing color), but I did a cap kit on it and replaced the B+ cap. But I noticed that the deflection yoke wiring was different as I had seen posted by others in pictures (including a Mike's Amateur Monitor Repair video).

The labels are all missing, but the outer pair are wired Yellow and Green, and the inner pair are Blue and Red. It looks like the "correct" way is outer Blue/Red, inner Green/Yellow. Can anyone confirm? Why might this one be wired this way? It was for a vertical cocktail game.

On the main board, there are following connections (matching the schematic):
yellow - TP14 (vertical)
green - TP13 (vertical)
blue - TP12 (horizontal)
red - TP15 (horizontal)

Thanks!

 

[mecha]

measure at the tabs on the yoke. if the outer yellow/green ones are high resistance then those are the vertical pair, and do same for the inner red/blue, if that's low resistance, that's the horizontal pair. the yoke could just be run to the tabs backwards.

 

[jcosper]

I did do that... the outer two are 8.2, inner 2.5. So... its wired correctly?? How common is that to run the tabs backwards?

 

[mecha]

I may have seen it before. there should be labels on the board the tabs come out of look for Y B R G (or whatever the combination is lol)

also if you had it wired backwards the monitor wouldn't start and the vertical transistors on XY board will be nuked. lot of people color code the tabs with appropriately colored Sharpies to make it easier for whoever acquires that monitor later.

 

[jcosper]

OK thanks for the insight. There were no labels on the yoke tab, but I will be sure to add them.

 

[mecha]

can you take pictures for posterity?

 

[jcosper]

Here it is in all its filthy glory. This was taken before I did cleaning and cap kit...

 

[behrmr]

I recently acquired a sad K4600 with P297 interface board. It has many issues (triple image, missing color), but I did a cap kit on it and replaced the B+ cap. But I noticed that the deflection yoke wiring was different as I had seen posted by others in pictures (including a Mike's Amateur Monitor Repair video).

The labels are all missing, but the outer pair are wired Yellow and Green, and the inner pair are Blue and Red. It looks like the "correct" way is outer Blue/Red, inner Green/Yellow. Can anyone confirm? Why might this one be wired this way? It was for a vertical cocktail game.

On the main board, there are following connections (matching the schematic):
yellow - TP14 (vertical)
green - TP13 (vertical)
blue - TP12 (horizontal)
red - TP15 (horizontal)

Thanks!

There are different yokes. Yours is the one where the colors are hash marked on the yoke.

If you had your yoke connected wrong you would have no image and blown parts on your XY card and main chassis.

The triple image is usually resolved by adjusting L351. With the monitor off adjust it to the extreme left, then extreme right, so you can determine where the center would be. Then adjust to the center. Power the monitor on and adjust until your image is correct. If the monitor shuts down during adjustment then you went too far. Back it off and start over.

 

[jcosper]

Thanks! I will play with that when I get it back together.

 

[mecha]

Thanks! I will play with that when I get it back together.

exercise caution when adjusting L351, that's an unobtanium/irreplaceable part if it breaks (still, to my knowledge, unless security is working on inventing a new one LOL)

as far as I know that's a very coarse horizontal hold adjustment, it's akin to literally moving the goalposts because you're moving the traditional H. Hold pot's adjustable range. so I would suggest centering H. Hold before mucking with L351 and turn that super gradually until you lock in or get it close to locking in and then you can use H. Hold to clean up the rest. it's a very routine procedure for me, so I'm trying my hardest on almost no sleep to explain what to do.

There are different yokes. Yours is the one where the colors are hash marked on the yoke.

If you had your yoke connected wrong you would have no image and blown parts on your XY card and main chassis.

The triple image is usually resolved by adjusting L351. With the monitor off adjust it to the extreme left, then extreme right, so you can determine where the center would be. Then adjust to the center. Power the monitor on and adjust until your image is correct. If the monitor shuts down during adjustment then you went too far. Back it off and start over.

I alluded to hooking the wires up wrong in my post above (ask me how I know... I'll tell you, I work in a dark arcade and mixed green and blue up years ago) I may have been aware of the different yokes, but thanks for the visual aid of the Sharpie markings, that's exactly what I was talking about. even the mungos in Texas were pretty good about doing that.

 

[jcosper]

I will do my best to be gentle. Even though I tire of breaking stuff, I somehow still manage it. I'll post when I have an update.

 

[behrmr]

I will do my best to be gentle. Even though I tire of breaking stuff, I somehow still manage it. I'll post when I have an update.

L351 is pretty easy to adjust don't worry about it. You'll need a small pocket type flathead screwdriver. There's a small hole in the frame of the monitor chassis to put the screwdriver through. Get it set in there before you fire up the monitor so you're not reaching through things to adjust it. This is it below (courtesy Bob Roberts).

 

[jcosper]

OK getting closer. Monitor comes up, but I can't seem to find that sweet spot that locks it in. The triple image is related to L351, and I actually got it nicely locked in once, but as I was adjusting other parts, it went back to this mode. I also tried the service manual method of grounding out TP32 through 1uF cap without much success/difference.

I would guess its something on the Vret/Hor board, but not sure where to start (maybe TR351?). Or looking at the Interface board TR201/202/203. I don't have another board to swap in, which would be cool.

On a side note, do you notice that B+ voltage moves as you adjust various pots? Is this typical? I would see it move +/- 2-3V.

Thanks!

 

[jcosper]

Also, what is VR601? I think this is a rough adjustment for width (since it is in series with the width coil), but it doesn't seem to be in the manual or on the schematic. I thought I read somewhere it was a rough, three position (or four if open?) adjustment since the K4600 doesn't have a dedicated pot.