What's causing this? (K7000 13")

Patrick Verner

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I bought this off ebay a long time ago. It's been a good monitor in my Gorf on location for years. The red gun was shorting, so I quick swapped in a K4700. I ran a clean and balance on the bench and the red gun is now fixed. I noticed these squiggly lines and no adjustment could take it out. This was advertised as having been recapped, but the B+ was not replaced. The B+ voltage is 125v and I don't have a new pot on hand. 25% of the time these end up breaking no matter how careful I am removing the glue.

Is this caused by the old B+ cap or the +2v? Or something else?

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K7000 does not have an adjustable B+ value; the pot you're talking about is just the shutdown adjustment. Is the neckboard connected to the chassis frame and also the dag wire around the tube? This picture looks like the neck isn't connected to the dag. 125vdc isn't egregiously out of spec; I would check the joints on the VR and the value of R301 (big one on the heatsync) 220 ohm is the value for the 19" chassis, I believe 13" is the same.

Also check the part number of the VR; i believe it's STR-30123 (123vdc)

I do have a 123 IC4 I can try.

Going though the chassis, the only 2 things I have found different from a 13/19" is the different Vertical IC and the B+ resistor is a 440ohm version.

This kind of tracks as the 25" version is 180ohm and the 19" is 220ohm. So going down in size makes a bigger resistor I guess.
 
Neck board ground and dag wire have continuity. That all looks good.

R301 is about 200 ohms.

I've never really looked this chassis over. FFS...

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Those squiggly lines are usually caused by too much contrast. Backing off the contrast doesn't eliminate the squiggles?
 
Those squiggly lines are usually caused by too much contrast. Backing off the contrast doesn't eliminate the squiggles?
I've already messed with the knobs as much as they can be messed with. This is what it looks like with optimal settings. It gets worse with the contrast turned up.
 
I'll tell you what it isn't: the B+ being off by 2V.

did you adjust H. Hold? lot of people forget about that cause it's not on the remote board
 
I was searching the internet for more pictures. Check this out:


Exactly the same wave. Is it possible it's just the K7000 not liking the TPG? @Kaelan

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You can't always rely on the TPG. You need to install it into a game and see how it looks. TPG can sometimes create some weird effects like this. And as someone else mentioned, your screen control and/or contrast need to be adjusted to a good black level. Backing off either of those usually drops the squiggles off.
 
I'm going to replace the horizontal output transistor. That's right in the area of the all the other burnt up crap and bodge wires. It's original. I was reading some other TV forums and this is classic dried up cap in the high voltage circuit or bad horizontal sweep. Adjusting the contrast down to zero is a band aid hiding a problem. I have fixed 30 monitors now and this is the first time I have seen this. My other k7000 can have to contrast turned all the way up and this still doesn't happen.

Are there any known bad batches of flybacks from the 2018 era? That's when I bought this.
 
This was already said 3 times. I can turn the contrast down and it's still there. It doesn't matter what combinations of knobs are adjusted. I tried everything.
My comment was for the the picture you provided of the other fella with the same problem
 
It's hard to tell from your picture, but it doesn't look like these are supposed to be touching.
 

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I'm going to replace the horizontal output transistor. That's right in the area of the all the other burnt up crap and bodge wires. It's original. I was reading some other TV forums and this is classic dried up cap in the high voltage circuit or bad horizontal sweep. Adjusting the contrast down to zero is a band aid hiding a problem. I have fixed 30 monitors now and this is the first time I have seen this. My other k7000 can have to contrast turned all the way up and this still doesn't happen.

Are there any known bad batches of flybacks from the 2018 era? That's when I bought this.
why would you replace the HOT? it's obviously working. as is the flyback.

if you watched my K7000 video you'll find a significant portion of it is dedicated to solder cleanup. the people that just replace caps and install a new flyback for no reason and ignore the rest, that's reckless.

you don't service monitors to run them with TPGs, put it back in the game and see what it's doing there.
 
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