K7000 in shutdown no B+

PrairieDillo

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Donor 2011, 2024
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I'm trying to fix a K7000 that may have a multitude of issues because at one point it did fire up the tube with a white screen. I capped it and then it would come up and then shut down very quickly. Since then I did basically everything on it.

It's got all new caps, Flyback and I checked the HOT. C38 was pulled and checked.

I had two donor chassis so I swapped the big filter cap at C55 since I wasn't getting any B+

I've checked the diodes in the bridge/power section.
I don't think I've checked C36 the critical safety cap yet.

I have a question. ON R103 the vertical caged ceramic resistor, mine is reading like 4/5 ohms but isn't blown. This is higher than the 2.7 rated. Even on my donor chassis, they all read high compared ot the rating. So of the three, that I pulled and checked (looking to put the closest one into the one I'm trying to fix) none are close to the 2.7 rating.

Could this higher range cause shutdown?
 
When you say "no b+", do you mean it is zero? Where are you measuring it?

R103 seems fine, so check the fuse, make sure IC4 is good, check R101, R89, the aforementioned C36.

You did put the insulator behind the HOT when you replaced it?
 
B+ was reading zero. Fuse was good and the holders were strong.

I only tested that the hot wasn't bad by checking the middle and third leg under bobs "dead" page for K7000. I may change the HOT since I have a new one.

How does one check IC4? The Shutdown pot looks clean still but it's sealed under something so how does someone check that one?

Thanks for the help!
 
If you have a ZERO for B+, and your fuse is good, then don't bother with the HOT right now if it tested okay under that method. Do you get ANYTHING at either end of that big white resistor?
 
If you have a ZERO for B+, and your fuse is good, then don't bother with the HOT right now if it tested okay under that method. Do you get ANYTHING at either end of that big white resistor?

You mean the resistor where B+ is measured?

I will do more voltage measures w/ the chassis out tonight. I'm too afraid to hook it up when its in the monitor.
 
You mean the resistor where B+ is measured?

I will do more voltage measures w/ the chassis out tonight. I'm too afraid to hook it up when its in the monitor.

You need to invest in a set of alligator jumpers. Connect one end to the resistor and the other end to your meter. Do the same with the black lead and the frame. Then power it up and check the reading...
 
Yeah that's how I measured it but I didn't measure other stuff in there
 
C36 the critical cap seemed good.
The B+ resistor was measured good but I am not getting anything at B+

I checked the fuse holder and power coming in. 130V coming in... after that I don't know where it's getting lost.

I may just give up and send this to you Mod for fixing. The chassis is really clean and I think that it'll be good down the road. Sigh....
 
The B+ resistor was measured good but I am not getting anything at B+

You don't get any voltage on EITHER end ?

There is a difference, which is why it's being asked.
One end gives you an idea of the B+ "input", the other end gives you an idea what the B+ "output" is doing.
 
C36 the critical cap seemed good.

Did you check the value? How does C36 look? Is it the large 4 legged one, the orange one or a blue one? If it's the blue one, those are usually a lower value and need to be changed if the monitor doesn't fire up after a capkit or flyback change.
 
I only measured the red side and got nothing.

Did you check the value? How does C36 look? Is it the large 4 legged one, the orange one or a blue one? If it's the blue one, those are usually a lower value and need to be changed if the monitor doesn't fire up after a capkit or flyback change.

It's a Blue one... I also have a green one from another chassis but they were the same value. As it was rated. So they both looked fine.
 
I only measured the red side and got nothing.



It's a Blue one... I also have a green one from another chassis but they were the same value. As it was rated. So they both looked fine.

Measure both sides of the big white resistor, and give us the value. Make sure you are measuring DC volts.

And does C36 say .0061 or 612? Or does it say .0043 or 432?
 
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