K7000 No heater glow

Kyrosfear

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Gentlemen,
I just did a cap kit and flyback replacement on a K7000. Upon powerup, I hear the monitor's high pitched whine (I am not sure what the technical term for that is), but I get no glow in the yoke. I checked to make sure I did not bend any of the yoke pins, and they are all fine. I have the manual from WG, which says "check filament circuit" but I am unsure how to proceed with this directive because this is the first chassis I have ever attempted to work on myself. Please provide any suggestions you have regarding troubleshooting this issue.
Thank you.
 
Sounds like one of the many bad solder/trace issues common with the board.

Figure out how and where to test the B+ voltage, make sure the fuse is good, and report back with the B+ value...
 
I appreciate the help, very much. It is a 25" monitor. The number on the neckboard is "025A1342-001".

The manual says to check the B+ at "IC4, Pin4; Neck Board, P202, Pin 3." Does this mean one lead goes to IC4 and the other to P202, or that the B+ can be checked at both locations?
 
check R213 on the neck board to see if its open or two far out of tolerance.

that is in line with the heater and the trace from the fly.


Peace
Buffett
 
It is shorted. I will order a replacement and update this thread upon completion and test. Thank you for your help.
 
resisters are supposed to be shorted. if it is open then it is bad.

put your meter on ohms and see what the value is.

Peace
Buffett
 
It is shorted.

You sure about that?

The manual says to check the B+ at "IC4, Pin4; Neck Board, P202, Pin 3." Does this mean one lead goes to IC4 and the other to P202, or that the B+ can be checked at both locations?

Either....those are two separate test points.... negative meter lead goes to ground (any heatsink).

Pin 4 of IC4 is actually easier to test at R301, which is the large ceramic resistor mounted to the side of the chassis. One side will be about 145vish, the B+ side will right at 130v. (DC voltage)

There are also common broken solder joints near the center of the chassis around some of the larger resistors that will cause a no neck glow scenario. (R91, R93, something like that, I don't have one handy to glance at)
 
Although I greatly appreciate the help, when I turned my test machine back on (where the monitor is located) to check the voltage at Pin 4 of IC4, a small puff of smoke came from the center of the chassis and it is completely dead now. I am going to pull it again and see if I can figure out what happened. Thanks guys.
 
i bet you have a multitude of cold solder joints and fried traces on that chassis.

read the K7000 sticky at the top of this section to see where most of them are.

also update your general location so maybe a local member can help you.

Peace
Buffett
 
Ok, the smoke was the resistor R96. My board is charred around both solder points. I tested the resistor out of circuit and it is open. Should this be a simple replacement of the resistor or is this a symptom that something else is wrong?
 
clean and re-flow all the solder joints/pads.

it may have burnt up due to poor contact all this time. i have seen this before on other chassis. replaced it and it was fine after a good clean and re-flow.

Peace
Buffett
 
You are correct. I can already see at least one fried trace. What is the best thing to do with those, run a jumper? I will proceed to resolder the questionable joints. I am located in Emporia Kansas.
 
you can jumper them if you wish. i usually use a left over cap lead or scrape the green mask off the trace and bend the lead over to touch it and resolder to the trace.

well i am not local to you. update your location in your profile as well.

Peace
Buffett
 
Fair enough. I will update this post once I resolder the joints, replace R96, and fix the fried trace. Thanks for the help.
 
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