Recapping a K7000 monitor tomorrow (wash the tube?)

[Tighe]

WOW Bad caps!

I am installing the Bob Roberts cap kit and check out just the first 2 I swapped!

Leaky!

 

[Tighe]

Finished

In Bob's kit there is one capacitor (C204) that is on the neck board, which I skipped because he says it is 4.7 µf 250v while the one there is .01 µf.

Other issues:

Here is the crack I found on the neck:

Seems to work anyway, it is only in the plastic.

The bottom has these burned contacts I assume were done by the person who soldered them.

Also there is a coil on the board that is burnt and has yellow crystals on it. I blew some off with the air compressor, anyone know where I can get a replacement, and if it is worth it?

 

[Tighe]

Woops

OK so I put it back together, and I get this:

If I turned this would it cause that to happen?

 

[Tighe]

Ah fuck

I powered it down and turned it some more, and now nothing, the tube makes noise, but black. I don't know what to do now. Help!

 

[KevinMullins]

None of the things you asked about earlier are of too much concern... the plastic piece on the tube, the little transformer, the burn marks are just old flux from soldering.
That width coil should not have to be turned all the way out like that though, run it back down in until about flush with the top, that's a good starting point.
Almost looks as if you had no video input on that blueish screen, and the SCREEN voltage on the flyback may have been a tad high causing the white lines.

But it almost does look as if you may have the Zenith made K7000 (K7000a).
(olive drab green kinda colored flyback)

Take a couple good pics of the entire chassis, top and bottom and of the neckboard as well.
As close as possible to be clear, but show the whole thing. (want to check solder joints for ya)

Oh, and I just have to ask. you did have the yoke plugged back in right?
(just noticed it wasn't during those pics)

Did you also verify the "values" of all the caps as you changed them?
If you do have a K7000a then I'm not sure if any would be slightly different. (been meaning to drag one of mine out and compare values on everything)

 

[KevinMullins]

Oh, and I just have to ask.... you did have the yoke plugged in right ?
(just noticed it wasn't during those pics)

 

[Peale]

Oh, and I just have to ask.... you did have the yoke plugged in right ?
(just noticed it wasn't during those pics)

Has to be - otherwise there wouldn't be retrace lines, there would be a dot in the middle.

 

[Tighe]

None of the things you asked about earlier are of too much concern... the plastic piece on the tube, the little transformer, the burn marks are just old flux from soldering.
That width coil should not have to be turned all the way out like that though, run it back down in until about flush with the top, that's a good starting point.
Almost looks as if you had no video input on that blueish screen, and the SCREEN voltage on the flyback may have been a tad high causing the white lines.

But it almost does look as if you may have the Zenith made K7000 (K7000a).
(olive drab green kinda colored flyback)

Take a couple good pics of the entire chassis, top and bottom and of the neckboard as well.
As close as possible to be clear, but show the whole thing. (want to check solder joints for ya)

Oh, and I just have to ask. you did have the yoke plugged back in right?
(just noticed it wasn't during those pics)

Did you also verify the "values" of all the caps as you changed them?
If you do have a K7000a then I'm not sure if any would be slightly different. (been meaning to drag one of mine out and compare values on everything)

Thanks, I turned the screen up so I could see something. Now the tube doesn't power up, when I turn it on it clicks 3 or 4 times and gives up.

The thing I might have done wrong was the plug that goes to the white strap around the monitor. I might have mixed up the polarity.

I am headed out for the day, I will post photos tonight. I sure hope I can get this working.

 

[KevinMullins]

The thing I might have done wrong was the plug that goes to the white strap around the monitor. I might have mixed up the polarity.

The degauss coil ?
You can't plug that in backwards..... it's AC voltage, so it doesn't matter which way it's plugged in.

 

[modessitt]

If you had retrace lines, turned the horizontal width coil, and now have nothing on the screen, then you most likely have cold solder joints in that horizontal output section either on that width coil or the power resistors and mylar capacitors nearby. This is very common. Wiggle each of those big parts while watching the solder underneath. If you see any that look to be moving, reflow the solder until they don't. See if that helps...

 

[Tighe]

If you had retrace lines, turned the horizontal width coil, and now have nothing on the screen, then you most likely have cold solder joints in that horizontal output section either on that width coil or the power resistors and mylar capacitors nearby. This is very common. Wiggle each of those big parts while watching the solder underneath. If you see any that look to be moving, reflow the solder until they don't. See if that helps...

I reviewed all the caps and and I did them correctly. Here is a link to a album with photos of all the caps and the board top and bottom.

http://picasaweb.google.com/tigheklory/CapKit

I also checked all the solders and they look good. I found what I think is a open between R104 and D23. The continuity tester shows continuity in both directions. Shouldn't a diode only only have continuity in one? Heck I don't know what I am doing. I am good at soldering, but I have never worked on a monitor before. All I know is that every time I take that neck board off, more plastic falls off. These Zenith monitors are real POS. I am this close to spending the $299 for a new Makvison 25". Even if I fix this shitty monitor it will break again, and by then I won't be able to buy a new monitor.

I did the same thing with the 19" in my Galaga that lost horizontal. Bought a new Vision Pro and it looks so much better (darker blacks) then the old tube.

Anyway I will give a few more tries, I would feel great if I did get it working again! So please look at the album and let me know if you see anything wrong.

 

[Tighe]

I think that the tube is toast

I think that the tube lost vacuum, I can hear it click 3 times and then no neck glow. I don't think I did anything wrong with the board, I think that the neck gave up after pulling it 5 times. The plastic is really brittle, and one of the pins was sticking out further than the rest.

 

[Fudd]

if the tube was cracked it be glowing blue, under normal operation it glows orange. what is yours doing?

 

[Tighe]

if the tube was cracked it be glowing blue, under normal operation it glows orange. what is yours doing?

No glow, clicks 3 times on power on.

 

[Michael Roma]

Ignore... I just saw your pictures.

- Mike

 

[KevinMullins]

Sounds like HV shutdown.
Measure the B+.

Did you verify all cap values AS you replaced them?

BTW - That IS a K7000a.... if the flyback dies there is no replacement for it.

 

[splattergatz]

an ESR meter checks the capacitance of a capacitor. just a few weeks ago, found a batch of bad 100uf 50 volt capacitors which almost got installed in a monitor chassis was working on. not saying thats whats wrong with yours or the chance you have a bad capacitor is very, very low but if you are going to be doing this a lot you might want to buy one. that way you know the ones you are taking out are bad and the ones you are installing are good.

dont have a lot of experience with that chassis but i do know that grey little box in the red anode wire is a capacitor. its for gun games that has a flash on the screen when you fire the gun.

 

[Peale]

an ESR meter checks the capacitance of a capacitor. just a few weeks ago, found a batch of bad 100uf 50 volt capacitors which almost got installed in a monitor chassis was working on.

What brand?

 

[Tighe]

Sounds like HV shutdown.
Measure the B+.

Did you verify all cap values AS you replaced them?

BTW - That IS a K7000a.... if the flyback dies there is no replacement for it.

By verifly, you mean check to see that I am replacing with the same f and >= voltage? Then yes.

Where do I measure B+? What kind of values should I be getting? This is the only meter I have, it only has 2 VAC settings 200 VAC max and 600 VAC max.

 

[Peale]

B+ is measured in DC, not AC. Set it for 200VDC.

Black lead on the frame, the other on the far end of the large white ceramic resistor bolted to the frame.