k7000...Uncle....

ThunderBunny

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I have been jacking around with a k7000 chassis for a month now and I'm done. It's blowing it's fuse as soon as I turn it on. Here is a list of what I have done so far.

1. Replaced HOT(it was bad)
2. Replaced C36
3. Replaced the 4 suspect diodes D19-D22(just to be sure)
4. Replaced flyback
5. Checked D18
6. Replaced the VR(it was bad)

One thing I noticed before steps 5 and 6 was that R100 was touching R80. I have reflowed a bunch of spots that looked suspect also. Any other ideas?

edit:Oh and a cap kit to start
 
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Check the power supply diodes..should be 4 matching. I have a bad feeling though, depending on the order of what you replaced when, you probably have another bad HOT.
 
Just checking here - you have been metering these parts before just throwing new parts at them, I hope?

If it's blowing fuses, something's shorted.

Critical Safety Cap (CSC)
Horizontal Output Transistor
Other Mylar caps
Bad flyback

I'd check the Mylar caps, and the horizontal output transistor.
 
I metered them out. Original HOT showed short and so did the VR. C36 was sketchy, so I replaced it since I had the part in hand. I'll be checking the HOT again, but I have a new one on the way. The diodes D19-D22, on the other hand one was bad, so I replaced it along with the other ones just because I was there.
 
C38 is probably shorted.

If you give up, I fix these (standard-res only) for $50 + parts + shipping...
 
I metered them out. Original HOT showed short and so did the VR. C36 was sketchy, so I replaced it since I had the part in hand. I'll be checking the HOT again, but I have a new one on the way. The diodes D19-D22, on the other hand one was bad, so I replaced it along with the other ones just because I was there.

Dumb question, you do have the insulators behind the HOT and the VR right? Even if they are there I like to meter the tab on the HOT to GND to make sure its not shorted.
 
try unsoldering the HOT, slap another fuse in and fire it up.....if it blows again, I'd say you can focus on the power supply....saving alot of time and replacing good parts. Make sure you have installed the diodes correctly and there are two more diodes used to protect the degaussing circuit that you can check. Wells has the schematic online if you need it. Good luck....
 
You might also try unplugging the degaussing coil and or removing the MTC (or whatever its called) that powers the coil. If its stuck on and the coil is drawing power all the time it will probably blow that fuse fairly quickly.

BTW, when the fuse pops does it just lightly pop open or does it flash and leave the glass on the inside of the fuse all blackened?

On the u2000's and u5000's you could isolate the b+ output by lifting a jumper and run it to a 120VAC 60 watt light bulb. This would keep you from frying deflection parts and would load the power supply so you could see where your problem lies. You can do the same thing on a K7000 by lifting one side of R101 and one side of R89 but you have to cut the trace heading into the horizontal drive section. I've done it a few times but its not for everyone. It will at least save some HOT's if its your power supply with the problem.
 
try unsoldering the HOT, slap another fuse in and fire it up.....if it blows again, I'd say you can focus on the power supply....saving alot of time and replacing good parts. Make sure you have installed the diodes correctly and there are two more diodes used to protect the degaussing circuit that you can check. Wells has the schematic online if you need it. Good luck....

You know, I think I tried that and it didn't blow but I'll try it again
 
Ya know, in this day and age of cheap s***ty parts its not unheard of to have a bad flyback out of the box.

Have you checked the horizontal yoke impedance? Post the results here.
 
Ya know, in this day and age of cheap s***ty parts its not unheard of to have a bad flyback out of the box.

Yes I have had several brand new k7000 flybacks bad right out of the box in a row. I think that's part of the reason k7000 flybacks are in short supply or out of stock right now.

Remember, the voltage regulator should only be replaced with the correct numbered part as the original. STRxxxx are different pinout than STRxxxxx series. The B+ and ground leads are swapped on those and will blow the fuse if you have the incorrect part installed.
 
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Ok, pulled the HOT and it didn't blow the fuse.

gamefixer - How do you check the horizontal yoke impedance?

Ken - I have been hoping the new flyback wasn't bad after all the reading I have been doing. I had tried Bob for the flyback, but he was out, ended up getting it from Twisted Quarter. I replaced the VR with the same number.

Mod - I used Dynex...maybe just as bad. Only thing readily available around here.
 
Ok, pulled the HOT and it didn't blow the fuse.

gamefixer - How do you check the horizontal yoke impedance?

Ken - I have been hoping the new flyback wasn't bad after all the reading I have been doing. I had tried Bob for the flyback, but he was out, ended up getting it from Twisted Quarter. I replaced the VR with the same number.

Mod - I used Dynex...maybe just as bad. Only thing readily available around here.

Just use your volt meter in ohms and measure between the red and blue wires on the yoke connector. For the sake of checking you should also check between red/blue and yellow or green.

Does that Dynex have silver in it? If so its conducting electricity and probably part of your issue.
 
Red/Blue - I get 1.5 to 1.9 and Yellow/Brown - I get 10.1

The compound is completely white, so I guess it's ok

All of that seem within reason.

When the fuse blows "how" does it blow. Bright flash or small tick and its gone?
 
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