Recapping a K7000 monitor tomorrow (wash the tube?)

[Tighe]

Where

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.

OK Great, Now I am not sure of the locations you told me, so I took a picuture and labeled the possible locations (I could be completely wrong)

OK so where do I measure A, B, C? Or somewhere else?

 

[KevinMullins]

Between chassis ground and "B".
Can also measure at "A" and let us know what that is.

Remember, DC voltage, look for 123-130 volts on "B".
May be higher on "A", like 145-155v.

 

[Tighe]

Between chassis ground and "B".
Can also measure at "A" and let us know what that is.

Remember, DC voltage, look for 123-130 volts on "B".
May be higher on "A", like 145-155v.

LOL OK so the frame of the monitor is not chassis ground, Got a nice HUGE spark when I touched the tester to the frame and B. OK so I will try again.

 

[KevinMullins]

Just use the heatsink right there where everything (the resistor) is mounted.
But either way you should not have gotten a spark by metering to the frame.

 

[splattergatz]

What brand?

no, im not a salesman

its an Atlas ESR 70 made by Peak

here:
http://www.anatekcorp.com/atlasesr70.htm

and its a little bit cheaper now than when i bought mine
great device so far, also bought a ring tester from them so i can verify im installing/removing good/bad flyback transformers

 

[mecha]

there should be a green earth ground wire attached to the chassis. if I'm not mistaken, that's what links up the "ground" to the rest of the chassis when you screw it in, right? the black ground on the RGB header is just for the video signal. what do people call those... synthetic ground? lol

your tube frightens me.

 

[Tighe]

Between chassis ground and "B".
Can also measure at "A" and let us know what that is.

Remember, DC voltage, look for 123-130 volts on "B".
May be higher on "A", like 145-155v.

Voltage @ point B 152.1 V

Voltage @ point A 129.6 V

Those are off, so what do I do next? Does turning the screen knob change the value at those points?

 

[mecha]

if I'm understanding this correctly, if your B+ is running way high or too low like that, your monitor could just be stuck in HV shutdown. is it possible that's high enough that it just won't turn on? I've heard stories about the monitor at least being on for a monitor and then when a bright flash happens on the screen or 1 minute later, it'll shut off.

 

[Tighe]

if I'm understanding this correctly, if your B+ is running way high or too low like that, your monitor could just be stuck in HV shutdown. is it possible that's high enough that it just won't turn on? I've heard stories about the monitor at least being on for a monitor and then when a bright flash happens on the screen or 1 minute later, it'll shut off.

OK after taking it out and putting it back in a few more times, I seem to have neck glow now. I am even getting a picture, be it all black like before. It is almost like the RGB input is unplugged. I am uploading a video you Youtube right now. Will post when done.

 

[Tighe]

Haa haa ha!!

OK after taking it out and putting it back in a few more times, I seem to have neck glow now. I am even getting a picture, be it all black like before. It is almost like the RGB input is unplugged. I am uploading a video you Youtube right now. Will post when done.

Here is the video, I just tried plugging the RGB to the monitor into my MK cabinet that is right next to it and a K7000 too. Guess what. No video. I am pulling that cabinet apart again and looking to see if anything is unplugged inside.

I am hoping that this is just a unplugged cable.

EDIT: Woops forgot video:

 

[Peale]

no, im not a salesman

its an Atlas ESR 70 made by Peak

here:
http://www.anatekcorp.com/atlasesr70.htm

and its a little bit cheaper now than when i bought mine
great device so far, also bought a ring tester from them so i can verify im installing/removing good/bad flyback transformers

LOL...no, no...I mean what brand of capacitor? You said you had a few bad of that variety, and I'm curious because I just bought a bunch of that same value. I've had an issue with one of them, and now I'm concerned I should test the whole lot.

 

[mecha]

did you reflow the video header? I've never had to do it on the few K7000s we have, but I guess it's a common problem.

trying to think of why else you'd have a black picture. I still feel half asleep. wooo

 

[Tighe]

did you reflow the video header? I've never had to do it on the few K7000s we have, but I guess it's a common problem.

trying to think of why else you'd have a black picture. I still feel half asleep. wooo

I didn't reflow the header, the solders looked fine, but I will try that, because I was thinking there was a unplugged cable, but when I backed it up and plugged the cable to the neighboring MK cab it worked (after I realized I forgot to plug in the VGA cable after doing the video.)

But when I plugged the monitor back in again:

I guess I am taking it out again.

Anything else I should be checking?

 

[Tighe]

Another clue

OK so all the controls for the monitor respond like they should except for contrast. I am thinking that there is a problem that is causing it to have the contrast all the way down. I tested the remote board and it is good, I need to now check the wire from the board to the chassis.

 

[Tighe]

OK so all the controls for the monitor respond like they should except for contrast. I am thinking that there is a problem that is causing it to have the contrast all the way down. I tested the remote board and it is good, I need to now check the wire from the board to the chassis.

What I am thinking if the contrast is all the way down I wouldn't see anything.

 

[Tighe]

What now, please help.

OK so I traced the contrast all the way to C12. That is one of the capacitors i replaced. So I swapped it back and nothing changed. Still same problems. I reflowed the video input pins too. This monitor worked before I did the recap kit, but picture was now that great.

 

[splattergatz]

few bad

uh oh ! hehehe. uhhhh let me look...they were NTE
every other capacitor was waaaaay out of tolerance, some were down by almost half none were on and all were low if that makes sense.

synthetic ground

hahaha...no silly, thats logic ground. but i like the synthetic ground idea.
just *remember* hooking up your ground when testing voltages, you can/sometimes get screwy readings if you're ground wire is clipped to earth ground instead of logic ground when testing voltages on your PCB.

 

[splattergatz]

monitor worked before I did the recap kit

when replacing capacitors you have to be careful not to flex the board too much when you are moving it around on your bench. the traces can break when its flexed enough. try putting your DMM on sound and check for continuity between points in the section you suspect where the problem may lay. the pain in the ass about them is when they break they do go back together so you still might get continuity but when a load is placed on that circuit, it wont work so look real close at the traces too. dont just glance over at the next component in the circuit, you might see the break if you're lucky.

do you have one of those magnifing lens/lights or do you have a good pair of glasses i hope?

 

[Tighe]

when replacing capacitors you have to be careful not to flex the board too much when you are moving it around on your bench. the traces can break when its flexed enough. try putting your DMM on sound and check for continuity between points in the section you suspect where the problem may lay. the pain in the ass about them is when they break they do go back together so you still might get continuity but when a load is placed on that circuit, it wont work so look real close at the traces too. dont just glance over at the next component in the circuit, you might see the break if you're lucky.

do you have one of those magnifing lens/lights or do you have a good pair of glasses i hope?

Is that all I should do? Check for back traces?

 

[R3LL1K]

Is that all I should do? Check for back traces?

You might also want to try another jamma board in the cab. If the Naomi works on a VGA monitor but not in the cab it means that the I/O board might have an issue. Once that flyback craps out you're SOL. Instead of buying a whole new monitor you can drop in a Wei Ya chassis or just buy a working K7000 chassis. It would be a lot cheaper than buying another monitor.