Dead K7000 killed my other K7000 monitor chassis

PrairieDillo

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So here's a long story about how I have another two Dead K7000's now.

I picked up a cab that was dead and they cut the cord off of it just to give me a story about how the cab still works but just needed to re-connect the power cord. Well I got it home and got it hooked up because I had another Dynamo HS1. Plugged it in and I got blue crackle in the neck where normally I would see some orange monitor glow. Scared I turned it off and decided to swap in the Chassis from my other HS1 K7000 monitor to see if it was something wrong on the monitor chassis. There's a bulging cap that's pulled away even on the "bad" monitor chassis I noticed.

Well the power molexes for the chassis were of different types so I desoldered the power cable (white and black) and swapped them to get the working (previously installed a Delux kit a few weaks earlier on the good chassis.) Got it in and oh man.... more blue crackle in the neck of the bad machine OH no...

I swapped everything back to the good working machine and now.... the previously "good" monitor is now dead and it doesn't come up or even glow... fuse good...

Any ideas on where I may start? I didn't measure any voltages on the monitor while on... I'm a little scared of poking around in there. I checked the power coming out of the isolation transformers on both machines... Both 120~

Thanks Guys... it's late and I'm fustrated. I hope I can get the chassis I capped for my TMNT back in that machine... at least one working K7000 when I should have at least two of these working...
 
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"Blue crackle" in the neck of the tube means the tube is destroyed (vacuum leak). There's a crack in the tube somewhere and it's ruined.
 
Thanks Ken... can plugging in a working chassis damage it, to this tube?
 
There are couple things here:

a) as Ken said, if you get blue sparking INSIDE the neck, then the tube is cracked.

b) if you don't hook up the DAG ground wire from the neck to the neckboard, you'll get sparking from your chassis to various parts of your monitor frame and yoke. Eventually it will blow your fuse, VR, HOT, and even burn up resistor.

c) Check the fuse on your "good" chassis and see if it blew...
 
So I had two K7000s one was perfectly working.

Not knowing that the tube was blown I put the good chassis into the bad monitor to test... nothing... swapped it back into the good Monitor and it no longer worked.

Tonight I checked all of the ceramic resistors, fuse etc... still did not work.

I then went over the "bad" chassis and swapped in some used caps to it from another K7000 cap kit (TMNT 25") I recently to some obviously bulging caps. I threw that in and it worked.

Not knowing what blew in the good chassis... I'll now just bring those good new parts to the chassis from the blown tube monitor.... funny how that is... I barely ran my good chassis in the bad Monitor (blown tube)

I've still alot to learn. But I don't even see the HOT on a K7000

At least I am back to square one with my working monitor. Now in search for a new monitor for that HS1. It's a 19" but a friend offered me a 25" "working but untested" monitor. I can't see it fitting in that dynamo mounting board but I may give it a shot.
 
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Are you getting neck glow even on the formerly good chassis?

Just me logically thinking, but tube arcing can send high voltages to things that shouldn't have high voltages, and my first guesses would be the 2 chips or the voltage regulator if a bad tube were to kill something. I have seen dead tubes kill things - a B&W monitor I have that has resistors on the tube socket blew most of the resistors when the tube cracked. I fixed the resistors and it lives on though.
 
I've still alot to learn. But I don't even see the HOT on a K7000

It's a D1398 transistor mounted to the metal bracket that goes over the flyback. A good will show a reading of .400-.700 in diode test with the black lead on the base and the red lead on each of the other legs. Tests between the emitter and collector (either way) will show approx. .060 but that's okay...
 
No glow on the now bad chassis. Oddly this chassis was plugged in less long than the one that came with the monitor. The chassis that stopped working from the bad tube previously got a flyback and cap kit.

Thanks, I'll check that IC. I think my Fluke meter has a diode mode.
 
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