K7000 keeps blowing fuse?

[Popcorrin]

My K7000 keeps blowing the fuse.  It was working fine and then I tried to adjust the horizontal hold, I heard a little sizzle and the monitor went dead.  I checked the fuse and it was bad so I replaced it and tried to fire it back up and it immediately blew the fuse again. 

I pulled the chassis out and tested the hot and it tested fine, checked the solder joints and was checking a few capacitors when I found C37 to be shorted.  I replaced it along with the fuse and put everything back together and tried the monitor again and it immediately blew out the fuse along with C37.

Now I am stumped and I was wondering if Ken or anyone else had some advice.

Thanks in advance.

[grantspain]

if the fuse is blowing black then more than likely its a short on the primary side of the psu,you should look at the degauss coil(disconnect) for damage,the degauss ptc component for short circuit and the diodes on the bridge rectifier circuit
don't know why adjusting that pot caused this unless something moved on the chassis

[Ken Layton]

Common causes of the fuse blowing:

bad flyback

horizontal output transistor (you did remember to put back the insulator behind it didn't you?)

shorted diode D18 (the damper diode)

shorted cap c36, c38, c69 (if present)

shorted voltage regulator

shorted diodes in the power supply section

shorted degauss coil

On that cap you replaced, you did replace it like-for-like didn't you? In other words say a "metalized polyester" for a metalized polyester" of the same values/specs?

[Popcorrin]

Yes, the cap I replaced was the corresponding cap out of a working k7000 chassis I had laying around.

I checked D18, C36 and C38 and they all tested fine.  I will go check the other components you suggested and report back.

One question though,  if something was wrong in the power supply section or with the degauss coil, why would it take out cap 37 which is in the horizontal output circuitry?  I guess I wonder why this particular cap would fall victim while the hot, c36, and c38 are unaffected? 

Could a bad flyback take out this cap?

To be honest, I feel pretty clueless!

Thanks

[Popcorrin]

I checked C69 and it was shorted.  Is it possible that c69 being shorted caused the failure of C37 since they are on the same circuit? 
I am going to replace C69 and C37, anything else I should do while I am at it.

Where is the best place to get capacitors for C69 and C37?

Thanks

[StephenH]

You may want to order a Capkit from Zanen or Bob Roberts.

[Ken Layton]

You can get the correct capacitors from Bob Roberts. He also has a regular capkit and the flyback too.

Sometimes a shorted flyback can take out those caps you mentioned. Sometimes they just fail on their own too.

[SirPeale]

One question though,  if something was wrong in the power supply section or with the degauss coil, why would it take out cap 37 which is in the horizontal output circuitry?  I guess I wonder why this particular cap would fall victim while the hot, c36, and c38 are unaffected?

Good question.  The horizontal circuit is tied into the power supply.  Note on the horizontal part of the yoke that the red wire is far larger than the others? 

[Popcorrin]

Success!
I replaced C69 and C37 and it's working great.
Thanks for the help guys.