K7000 Help needed

jeff412

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I have a K7000 that is dead. I've replaced the HOT and caps. The Flyback physically looks good. The VR is shorted from pin 1 to pin 4. Is this normal? It is not blowing fuses, but I don't have any B+ voltages. Where should I look next?

Jeff
 
K7000.... never heard of it.

j/k

Did you scrutinize the chassis and neckboard for bad solder joints and/or cracked traces ?
Large resistor areas, may be a bit brown on the chassis, are always suspect.
 
nothing obvious-no obvious burn marks or broken traces. Should pin 1 be shorted to pin 4 on the voltage regulator?
 
B+ voltages

OK, my search mojo is a big fail.

Can anyone help me with the B+ voltage location for the K7000?
 
nothing obvious-no obvious burn marks or broken traces. Should pin 1 be shorted to pin 4 on the voltage regulator?

Pin 1 is the voltage input, pin 4 is the voltage output.... if I recall there should be continuity of sorts there, but not neccissarily a "dead" short. (more like a diode) I would have to pull a chassis out to double check myself.

Can anyone help me with the B+ voltage location for the K7000?

Between ground and one end of the LARGE ceramic resistor mounted on the heatsink.
One end is the voltage coming off the regulator, the other end is the B+.
One should be 145-150, the other about 130. (DC)
 
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IC4 Voltage regulator schematic......measure your B+ voltage on the resistor described above, it comes directly off pin 4 which is the output. ( pin 4 ---> resistor ---> B+ )
 

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With the regulator pulled out I am reading a dead short between pin 1 and 4. I get B+=0V. Fuse is good. If I measure across the iso I get 120 V, but if I measure either output leg to ground I get 60V. Should one leg of the output of the iso be grounded?

Jeff
 
Check the big standup resistor over on the back right of the board, completely opposite of the flyback.. .make sure that hasn't opened up.
 
Pin 1 is the voltage input, pin 4 is the voltage output.... if I recall there should be continuity of sorts there, but not neccissarily a "dead" short. (more like a diode) I would have to pull a chassis out to double check myself.

Between ground and one end of the LARGE ceramic resistor mounted on the heatsink.
One end is the voltage coming off the regulator, the other end is the B+.
One should be 145-150, the other about 130. (DC)

I'm getting 156 and 123 on the other side... after the cap, the monitor looks fine.
Is this anything to address?

Thanks
 
What's the actual number on your voltage regulator ? STR130 ?
There were a few different ones used with slightly different voltages.
 
Check the big standup resistor over on the back right of the board, completely opposite of the flyback.. .make sure that hasn't opened up.


Yep that was toast. Can't believe I didn't see it. It had a big black spot on it.

Now, what else could be shot because of this? It's a 2.7 ohm 7W resistor. Can you get that at radio shack?

Jeff
 
Replaced the voltage regulator and the 2.7 ohm resister and now she's working like a champ. Thanks for all the help!

Jeff
 
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