K7000 low HV

RetroHacker

Well-known member
Joined
Jul 14, 2008
Messages
4,313
Reaction score
109
Location
Schenectady, New York
Well, I just rebuilt a K7000 chassis (from a 25" monitor) - had the typical cracked flyback, was "dead" when it was in the game - blank screen. Fuse was good. When I replaced the flyback, the HOT tested good, so I left it. Did all new caps and put a new fuse in (old one was corroded). Now, I'm testing it on the bench, and I don't have a tube or yoke to connect it to. I've got my HV probe on the output of the flyback, and I only get about 9kv. The B+ is right around 123v, so it doesn't seem to be in shutdown.

Ideas?

-Ian
 
the fact you have a b+ of 123 on a 25" chassis scares me. Most of these have a "5xx" chassis with a 130v regulator..

in any event, stop messing with it untill you get a tube and yoke. Youll end up smoking something else...
 
the fact you have a b+ of 123 on a 25" chassis scares me. Most of these have a "5xx" chassis with a 130v regulator..

in any event, stop messing with it untill you get a tube and yoke. Youll end up smoking something else...

If you do it right, then you can bench test without a yoke or tube...
 
If you do it right, then you can bench test without a yoke or tube...

Exactly. I do it all the time. I just very rarely work on K7000's, so i didn't know that HV wouldn't come up without a yoke. I *think* I have a 19" K7000 yoke laying around - will that work well enough, or will the different impedence throw it off? Does anyone know the DC resistance of a 25" K7000 yoke? I have a couple of assorted yokes here, and one 25" TV, maybe one is close enough?

For the record - this is how I bench test a monitor like this: tape the anode lead to the tip of the HV probe, and put it down into a glass jar. Then, I can monitor that the chassis is putting out the proper HV, and can check the B+ and other voltages. I do it pretty regularly with G07's and K4900's and the like.

-Ian
 
Don't use the 19" yoke, as it will generate a lot more of a field than it should.

The readings for the 19" and 25" yokes are about the same, but with a wider winding of course...
 
Back
Top Bottom