K7000 won't focus

AtomicBomb

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Bought a cab for short money with a "bad monitor". Cranked up the screen pot a little and got a VERY fuzzy image. Looked like brand new Xicon caps in it, so I skipped over bad caps and went right to changing the flyback (old one was a cracked white knob)... No change. Figured there might be a problem w the neck board, maybe a break @ the focus pin, so I swapped that with a known good, No change. Started suspecting the tube, so I hit it with my BK 480. All the guns are in spec now, but no change with the focus issue. Went back and checked all the caps just to be sure, they're fine. Ideas while I throw another chassis on this tube?
 
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Check your B+. There are a few resistors around the flyback that are on the secondary side off of the the windings for the HV, Screen and Focus. They may have changed value.

Might even be a problem over in the brightness and contrast circuit.
 
some of the chineses flybacks have poor focus.

i would swap a known good flyback on it to see if the problem is fixed.

put the questionable flyback on the known working chassis and see if the problem follows.


Peace
Buffett
 
focus is flyback controlled (tob knob) adjustment, neck board focus socket terminal pin or the tube itself has a corrupt gun.
anything beyond that would be unusual to rare. something along the lines of b+ / drive problem.
 
Based upon what you've already done, I would be focusing (pun intended) on the neck board. There may be something with the socket or spark gap.
 
Again, tried 2 different neck boards on chassis A (the second of which was known good) with the same result. As soon as I swapped in k7000 B, it was perfect.

Btw, when I say blurry, I don't mean a little off, I mean unrecognizable.

Unusual/rare isn't unheard of. I've had my hands in a lot of games.
 
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I did not. Just the original white knob and the repro. That was my last one, so I have to wait for more to come in. I did not experience any change between the two though.
 
Just repaired a 25" K7000 yesterday that had the same problem. Turned out that the anode wire was not making good enough connection. Spread the prongs further apart to get a better connection and now it focuses just fine.

Ed
 
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