K7000 won't stay on even with new chassis

Griffin

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I have a k7000 that will randomly not power on. It makes a static buzz initially like it's powering up the tube but then will stop. I even changed out the chassis for a fully reflowed, recapped and new flyback board but it does the same thing. I had to use the same neck board due to the pinout of the tube.

If I power off for about 10 seconds I get the same static sound as the HV powers up again.

Any ideas?
 
check the ac voltage going into the chassis, I had a couple that were producing too high ac volts and putting the chassis in shutdown.
 
Checked and it is at 125v which certainly higher than I would like, question is how do I get it down, it's coming from the transformer
 
This may seem like a stupid question but did you initially hook the ground wire from your neck board to the tube dag wire or did you fire the chassis without it hooked up. Often times this wire is missing and without it, these chassis love to eat regulators. Sounds to me like you now have a blown regulator so try pulling one leg of the D10 diode and see if the monitor fires and stays on.

BTW, the 125 volts you're getting at the monitor plug is fine and it's going to fluctuate a bit so I doubt this is your problem
 
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Now try this, if you have a k7000 19" monitor, take the 8 pin neck board off, attach it to your 25" chassis and install your 25" chassis on your 19" tube. I had to do this many times to test 25" k7's when I didn't have a 25" tube and it works but the one thing you need to do is adjust the vertical size pot all the way down or it will really labor your 19" yoke. It's going to run your image off the screen horizontally but it won't hurt anything, it's the massive vertical size that the yoke doesn't like.

This test will confirm if your neck board is in fact bad but I'd still try the D10 first
 
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Well that puts a damper on things doesn't it? I'm not sure why I thought you were working with a 25" chassis so I'm probably confusing you a bit. I don't suppose you don't have a machine with a 25" k7 in it? If you don't, try the diode and let's see what you get.
 
Changed all the dacs on the neck board as they are the only thing really sensitive. Plugged it all in and the picture came up, but a tiny tap on the chassis and it turns off again. The other chassis did the exact same thing. Could it be a shorting gun in the tube?
 
i am willing to bet your HV shutdown pot may be bad or dirty.

i have seen that happen from time to time.

the pot is possibly just on the threshold of triggering HV shutdown and when you tap on it it triggers.

you could replace the pot and see if it fixes your issue.

adjust the new pot to the same position as the old one, and test from there by turning it a little each way to see if you can reproduce the same results.

sometimes the glue can eat the pot up as well.

Peace
Buffett
 
Don't you think it's weird that I get the same behavior on two different chassis with this tube and neck board though?
 
no not really.

nothing surprises me much anymore about theses weird issues.
when you fix them for a living you see allot of strange things that make you go Hugh that is kinda strange.


does the game work with any other monitors without issue.

does the monitor work with any other games without issue.

do you have a video signal going to the K7000 when you are testing it?

i forget did you try pulling one leg of D10 to see if the chassis stayed on.

you can run it with the diode lifted for a wile just don't stand in front of it the whole time.

Peace
Buffett
 
Monitor does not work In a different cab, same issue.
Game works on another monitor but that's a glitchy one I keep for testing.
Does the same with or witho u t a video signal.
Havent tried the d10 test yet
 
between the 2 K7000 that are having issues what are the parts that were replaced or swapped between them that they both share.

example: if one needed a vertical IC and the other did not then that part is ruled out.

example: if both chassis needed IC1, then that is what i am talking about, as parts replaced that they have in common

Peace
Buffett
 
I bought a rebuilt, reflowed chassis with new flyback from ebay. I had to reuse the neck board from the original as the new board came with a ten pin and my tube is an eight pin. So the only common parts are the neck board and tube.
 
you have both the dag wire connected and the ground from the neck board to the heat sink connected correct.

Peace
Buffett
 
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