Noisy K7000

BeagleBoy

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I just picked up a 19K7901 off ebay. The picture is nice, the colors are good (after I adjusted them), and it's got just the tiniest curl at the top (which I'm fine with for now).

The problem: it makes a buzzing noise. It's not super loud, and it doesn't affect the picture, but there's a constant low buzz. I tried tapping the chassis at various places, but it didn't change at all.

Any ideas?

-Jim
 
Will do. I admit, I avoided the flyback because all I had onhand was an insulated metal screwdriver.
 
if the flyback looks like it's from 1492 or even has the infamous white knobs, and you want that thing to last awhile, I would change out the flyback and cap it just to be safe.

should operate just fine for a long time if you're just using it in your house every so often.
 
So I replaced the flyback, and the monitor is still buzzing. And to make matters worse, I'm hearing "ticking" from the new flyback's anode cap. I'm guessing the clips aren't making a good connection? The picture's solid, at least.

The old flyback's anode cap was definitely higher quality, so I'm probably going to swap the original back in (it's a later model one, not the infamous white-knobbed one).

So what's the likely source of the buzzing? The horizontal drive transformer? Thwocking on it with a plastic stick doesn't seem to have any impact on the buzz/hum. Do they go bad? And where can you get them? Happ lists them as a non-stock item, so I have no idea how long it would take to get one from them.

-Jim
 
Also, I'd like to make the picture wider, but I can't get the width coil to turn in either direction. I'd prefer not to snap the sucker, but I have no idea how much torque to put on it.

I realize I can swap width capacitors, but I'd like a working coil. Is there any hope for it, or are they pretty much done-for if they're stuck?

-Jim
 
just keep trying to work it..

worst case, POWER OFF, use a metal allen wrench to attempt to loosen it. You will likely break it, but hey if its sol anyways its worth a shot.

popping at the anode...discharge and recheck yoiur connection. Both fingers should be firmly seated underneath the hole..

make sure the surface where the rubber cap is is free of dirt dust etc. If its dirty it cn tryu to arc the high voltage out of there twoards the aquadag.

Some folks(myself included) have used a THIN layer of silicone paste around the OUTER EDGE of the anode cap. Dont get any in the anode hole or on the anode lead.
 
Hey, got it loose, and it's intact. Cool. Picture's now the proper width. Also, I gave the tube a good cleaning around the anode, and reseated it yet again. Fifth time's the charm, or the cleaning made the difference, because I got rid of the ticking from the cap.

One more question, though. The picture is pretty well centered, but it's a tiny bit high. Problem is, it's at the very bottom of its vertical range. The pot works fine, I can adjust it up and down, no problem (except for the picture being too high through the whole range). Is there anything in particular I should be looking at?

Thanks for the help!
 
R83 controls this - should be a 680 ohm, or , depending on where your K7000 came from, this resistor may be clipped or missing. Check if the resistor is there, check its value, etc. etc.

Decreasing resistance will lower the display, and increasing resistance will raise the display.

You can decrease resistance by putting another resistor in parallel with it. That will allow you to see if that will lower it properly. Then, you can purchase a single resistor to replace the original if you are happy with the results.
 
The problem: it makes a buzzing noise. It's not super loud, and it doesn't affect the picture, but there's a constant low buzz. I tried tapping the chassis at various places, but it didn't change at all.

Most monitors and TV sets make a buzzing noise when they're on. You shouldn't be able to hear it unless you're right up next to the back of it though. It won't be very loud - but buzzing is normal. As is a very high pitch, faint whine that you can only hear if you have good ears (15.75khz). And it'll be right on the edge of your hearing... I can walk in to a room an hear if the TV is on, even though I can't see it. It's hard to place the noise, or even concentrate on it, but I can tell it's there.

If you can hear the buzzing from the front of the game, it's too loud.

Whining, loud buzzing, squealing, hissing, clicking - these sounds are not normal.

-Ian
 
If you can hear the buzzing from the front of the game, it's too loud.

That's just it. I keep telling myself that the buzzing is too loud. But perhaps this monitor is just a bit noisier than the others I've got. It's not super loud, but it's there (I'd call it "normal" monitor buzz, but a bit louder).

Regardless, I think I'll just put it back in the cabinet and ignore it for now. Though I should probably cap it while it's out. Except it looks good as is. Lazy vs right thing..... sigh.
 
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