New Flyback Destroyed My New K7000

zenomorp

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Just picked up a working K7000. Installed a new fly and full cap kit. Fired it up and it looked great, got everything adjusted and all of a sudden the brand new flyback cracked and started arcing profusely. I turned the cab off immediately, removed the chassis from the tube, removed the flyback and saw this...



Damn thing was brand new. I've always heard about bad batches of flys but I've never ran into one. Well, looks like it happened this time. I re-installed the old flyback and when I powered the chassis on again, I got vertical collapse and then D13 smoked/shorted. So I replaced it, checked everything in that area, it all checked good and reinstalled/turned the chassis back on again. Poof! Fuse blew. HOT shorted.

So now I've got a lot more troubleshooting to do while I wait on the new HOTs I ordered to come in. ARGH!!

sigh-charlie-brown.jpg
 
fuck. Where did it come from?

For awhile bob and chad stopped selling due to failure issues, now the ones available are supposed to be better quality.

CHeck c36 and the vreg as well, its possible they got taken out when the flyback shat.

That really blows man.
 
I had a bad HOT in a K7000 kit. I was lucky that I was able to put the old one back in and get it working. Sometimes newer isn't better.
 
I got the Flyback from TwistedQuarter. I've ordered MANY cap kits/flys from them and NEVER had any issues. I don't even remotely consider it their fault. How could it be? As with all things electronic, you never know how long it's going to last. Regardless, I contacted them and told them what happened and I am awaiting a response. Hopefully, I can get a replacement but now I have a dead chassis that was working before that I have to fix. That's the most frustrating part for me.

On the vertical collapse issue, let me just say that I've never had a K7000 in VC that wasn't an IC issue but I have to wait until my new set of HOTs arrive (ordered 10 of them because I'm tired of never having any on hand) to start testing them. Oh well. First world problems.
 
--it happens. Years ago I had two brand new 7000s blow the flybacks after a few months. Both of them blew a hole in the top in the exact same spot. Luckily nothing else went out along with them.
 
the last 2 cases of K7000 fly's i have gotten have had no issues.

i had an older case that had issues, i told my supplier and he had the manufacture correct the issue.

AFAIK twisted quarter does not get their flybacks from the same supplier i do.
there are two different factory's making them at this time in china.

my flybacks have a different sticker on them, your sticker is different.
so i know they are from a different manufacture.

good luck on the fix.

Peace
Buffett
 
Partial Success!!

I received my HOTs and some solder wick from MAT Electronics today. Started troubleshooting....

-) Re-installed original flyback.

-) Installed new HOT.

-) Critical Safety Cap(s) test good in circuit.

-) VR was shorted across pins 3 and 4.

-) Replaced VR.

-) R107 tested OPEN in circuit. Replaced R107.

Found no other issues so I re-installed the chassis and powered it up. It fired right up but my exuberance was short lived because it was in vertical collapse. Damn. What's next? IC1?

 
Total Success!!

-) Tested R101 and it's traces. Good.

-) Replaced C51.

Still collapsed.

-) Tested R91 in circuit. Supposed to read 1.2 ohms (basically shorted). Meter didn't ring so I removed it from the circuit to find that it was completely open and burned up...





-) Replaced R91 and gave everything else another good lookover. Fired the chassis back up and...BAM! Collapse fixed and back up and running. Maybe this will help someone else in the future. TwistedQuarter contacted me and told me they are sending me a replacement flyback from a known good shipment so I'll install it when it arrives and hopefully it'll be ok this time.

-) All told, the bad flyback took out D13, HOT, VR, R107 and R91 (either directly or indirectly).


 
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Good stuff, glad you got it sorted.

Are TQ's cap kits still only partial kits? last time i got one from them it was missing a few caps that bob's kits come with, i hear buffets kits are even better.
 
So, the moral is: if you pick up a working K7000, DO NOT put in a new flyback and cap kit.

Got it.

I've seen 3 flyback failures in the past month, black knob variety. so I'm almost to the point that even if it's a white knob.. fuck it, let it rock. ;)

granted the black knob flyback failures I've seen didn't wind up putting holes in the chassis either but I digress. as a common rule, if the flyback isn't exhibiting any ill behaviors such as arcing, walking focus/brightness, or other unnecessary jitters in the picture, leave it be until it's done. especially true on Polos. biggest mistake I ever made was going with new flybacks on all of mine.

same goes with HOTs. I'm not a rocket scientist by any stretch but when you go replacing known good parts with new ones you're just introducing more variables. you never really know if they're good parts out of the box. you never know if installing said new part may lead to damaging other parts. so unless it's like a garbage picked K7000 that's doing nothing and you're gonna throw the whole shot at it, I wouldn't change anything that's working.

of course, I don't recall if zeno specified whether it was working or not to begin with. but job well done anyway.
 
Same problem here with a blown flyfack.
you can see the crack on the same spot on the flyback.

exactly same components were shot D13, HOT, VR, R107 and R91
This thread was a great help.
 

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Same problem here with a blown flyfack.
you can see the crack on the same spot on the flyback.

exactly same components were shot D13, HOT, VR, R107 and R91
This thread was a great help.

Awesome. Happy it helped you out.
 
I'm going to go back over my K7000 that had an arcing flyback and hasn't come back to life yet... R91 is the only component I haven't replaced off of your list.

Fingers crossed!!
 
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