My first tube swap, have Questions WG4600.

BrianS

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I have two functional 4600 chassis/tube/frames. One has a terribly burned tube, one was perfect but a guest at a party dropped something on the neck and broke it last week :(.

I bought two old 19" TV's from a thrift store last night. One was a 1986 Sears and it has a Toshiba tube. I checked the yokes vertical impedance and it was a match for the 4600 at 9 ohms. I did not check the horizontal impedance (did not know I should have, new at this!). Anyway the neck socket was the correct 10-pin although it only has 9 pins, the OEM tube also only has 9. So thinking the yokes were compatible I swapped the new tube into the old frame and hooked the whole thing up. The image was upside down so I did have to swap the vertical wires but it produced a better image that the oem tube did. The colors are off and the image choppy because the game PCB is no good- every monitor plugged in to this PCB looks the same.. And this chassis needs caps, but rest assured this is the same image the old tube generated.

So the image looks as fine. My question is- when I go back tonight and check the horiz impedance if it is a match can I go ahead and soldier on with this yoke?

Next question is, how close must the horiz impedance be to use the yoke? The vertical wasn't exact but it was within .2 ohms so I thought that was OK.

I don't want to swap yokes if I don't have to.

Thanks,
Brian
 

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If you already did the swap, hooked everything up, and it functions correctly you shoud be fine. I'd bet your horz impedence is very close to the original, within a couple ohms.

In the future you should check both of course...
 
OK, one more question then. The picture is not centered up, it is a bit high and the horizontal size is small. It looked like this with the old tube as well.

I think I know where the horizontal width adjustment is on this one but is there a way to move the vertical position down?
 
OK, one more question then. The picture is not centered up, it is a bit high and the horizontal size is small. It looked like this with the old tube as well.

I think I know where the horizontal width adjustment is on this one but is there a way to move the vertical position down?

yes, there is a jumper...
 
Fantastic, thank you.

Next step, now that it works will be to clean up the chassis and cap it.

Anyone have any service info on the 4600?

Thanks again!
Brian
 
Please post the model number (and a picture of the shell) of the Sears TV you found.

I have never found a TV that had a ~8.8 ohm vertical resistance yoke measurement in any TV set I've picked up. Most are all 14-15 ohms and a handful of 45-55 ohms.

The 2 Sears TV's I had from the late 70's had 12 pin tubes so were worthless for swapping.

I have lots of K4600 chassis that could use new tubes but I never want to do yoke swapping again.
 
Please post the model number (and a picture of the shell) of the Sears TV you found.

I have never found a TV that had a ~8.8 ohm vertical resistance yoke measurement in any TV set I've picked up. Most are all 14-15 ohms and a handful of 45-55 ohms.

The 2 Sears TV's I had from the late 70's had 12 pin tubes so were worthless for swapping.

I have lots of K4600 chassis that could use new tubes but I never want to do yoke swapping again.

Sure I can post that info tonight or tomorrow.

What is the problem with using the 14-15 ohm yokes with the 4600 chassis? I was thinking that as long as they were in the same range IE a LOW or HIGH impedance yoke then they would be OK to swap? The second tube I pulled out from the 1989 model TV did measure 14 ohms on the vertical and I was hoping to use that one too on my other 4600 chassis.
 
OK the Sears TV is a model# 562.42410550

Has "SR3000 Remote Control" printed on the front left. Woodgrain case.

I'll get the tube number tonight.

Here is a pic.
 

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Sure I can post that info tonight or tomorrow.

What is the problem with using the 14-15 ohm yokes with the 4600 chassis? I was thinking that as long as they were in the same range IE a LOW or HIGH impedance yoke then they would be OK to swap? The second tube I pulled out from the 1989 model TV did measure 14 ohms on the vertical and I was hoping to use that one too on my other 4600 chassis.

Yes they're low, but K4600's are VERY low. The resistance measurement (DC resistance at a specific frequencey) is a close approximation as to the impedence (AC resistance across multiple frequencies). However the low ohm yokes that the K4600 use just aren't compatible with a standard 14-15 ohm so you end up with numerous geometric distortions.

No, they won't blow up the deflection circuit like using a high ohm one, but you end up with too wide or too narrow screens, and then barrel or pincushion or corner tearing that cannot be adjusted out since the old chassis don't have fancy controls to adjust for that.

There are some pics up somewhere on the web showing a 15 ohm yoke on a K4600 -- I think it had pincushion and basically a square image that could not be expanded. Feel free to try and post your results -- It won't blow it up but I dont think you'll be happy with the geometry you get.
 
Yes they're low, but K4600's are VERY low. The resistance measurement (DC resistance at a specific frequencey) is a close approximation as to the impedence (AC resistance across multiple frequencies). However the low ohm yokes that the K4600 use just aren't compatible with a standard 14-15 ohm so you end up with numerous geometric distortions.

No, they won't blow up the deflection circuit like using a high ohm one, but you end up with too wide or too narrow screens, and then barrel or pincushion or corner tearing that cannot be adjusted out since the old chassis don't have fancy controls to adjust for that.

There are some pics up somewhere on the web showing a 15 ohm yoke on a K4600 -- I think it had pincushion and basically a square image that could not be expanded. Feel free to try and post your results -- It won't blow it up but I dont think you'll be happy with the geometry you get.

Good info, thank you.

The tube I have with 14 ohm impedance cannot have the yoke swapped per a sticker on the rear that says basically "this yoke is permanently attached, do not remove". So I guess I'll get one of those Wei-ya chassis for it.

One small sticking point I have run in to with the good Sears/Toshiba tube is the mounting tabs on the tube itself are in the wrong place. The tabs are all the way out at the front of the glass instead if being inset an inch or so like the others I have. Spacers can be made to correct this problem though. I'll post the tube part number info tonight.
 
I thought I noticed that yesterday that the mounting ears were inverted. Yes, I've run into that on newer (late 90's/early 2000's) 8 pin tubes like Sharp's. I've ended up tossing them because it ends up putting the tube too low so the back of the tube hits the chassis or the wires to the neckboard get stretched too far, and of course the bezels and stuff don't fit on top. But with 8 pin tubes they're easy to find a better tube with correct mounting anyway. A spacer on that should work fine.
 
Tube info:

I checked the yoke impedance against the 4600 yoke once again for confirmation.

4600 was 9.1 and 3.3

The Sears/Toshiba tube was 8.9 and 3.9

Tube model is A48AAB27X

It does not say anywhere on the tube if it is a 90 deg or 100 deg tube but there is a sticker with the number 9 visible on it, it is partially obscured by the clamp band so I don't know what the other digit is but I assume it is a 0 to denote 90 degrees.
 
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