Wg k7000? Bad focus, or dim picture (solved)

[abispac]

Edited to make the topic ore reliable: So this monitor has been caped, inspected for bad traces, and after that it has an ok image, turning focus on flyback all the way up it almost make the image look clear , but turning the brightnes a bit more makes the image look out of focus again.Only way to make the image look good, is by turning brigtnes low and and focus all the way up, it looks good but to dim, or dark. So im getting a flyback to see if thats the problem. Will keep updating this topic.  Pardon my bad english and grammar. Im just trying to fix this and hopefully help others that might have the same problem in the future.


So i found a beautiful monitor together with it's base and conections, the screen dont have any burnt in, and the pcb looks decent, a bit dusty but decent, it has like 2 blown caps and a badly burn  resistor. I would attempt a cap replacement as the monitor turns on but i get a greenish twisted image, hope the caps would fix it. Ive been trying to id this monitor and it looks alot like a k7000 but it has some small diferences, i couldt find an id number as the only stickers are fade up. Hope someone would help identify this monitor and put it back to life. Thanks for your time and advice.

[lilshawn]

yep.

 these are known for having a few variations as WG started farming out production to a few companies to keep up with demand at the time.

small differences and fixes and revisions and patches between boards here and there but for the most part they are true to schematic for the important bits that break down anyways.

[abispac]

yep.

 these are known for having a few variations as WG started farming out production to a few companies to keep up with demand at the time.

small differences and fixes and revisions and patches between boards here and there but for the most part they are true to schematic for the important bits that break down anyways.

Any advice on something that is a must do while I replace the caps?

[Zebidee]

Give it a bit of a clean maybe. However, you want to inspect closely for stuff like leaky caps first. You don't want to wash away the evidence before you've seen it.

[bobbyb13]

Give it a bit of a clean maybe. However, you want to inspect closely for stuff like leaky caps first. You don't want to wash away the evidence before you've seen it.

OOooo... this is really good advice I hadn't heard previously.

[abispac]

Give it a bit of a clean maybe. However, you want to inspect closely for stuff like leaky caps first. You don't want to wash away the evidence before you've seen it.

I saw a couple of leaked caps and i  know wich ones they are, but im gonna replace as much caps as i can, do you think its a good practice to replacerts even though they dont need to be replaced? like ive seen some burned looking resistors. Also ive seen the ic1 and ic3 can cause a problem similar to the one i saw in this monitor, like partially collapsed, also this model does not have the 50/60 pot, so i guess ill have to get me a groovymame pc with emudrivers in order to have a test machine and start posting some real pictures, but before that ill try to replace the caps.

[Zebidee]

Give it a bit of a clean maybe. However, you want to inspect closely for stuff like leaky caps first. You don't want to wash away the evidence before you've seen it.

I saw a couple of leaked caps and i  know wich ones they are, but im gonna replace as much caps as i can, do you think its a good practice to replacerts even though they dont need to be replaced?

Many people will simply "shotgun" replace all the electrolytic caps every 5-10 years. Leaky caps should definitely be replaced, but replacing all the caps just in case one is a little wonky. I personally don't, because it is unnecessary and wasteful. In most cases the caps will be perfectly fine for 30 years or more.

Instead, I use a Dick Smith ESR (equivalent series resistance) meter to check caps instead - With it, you can check capacitors without even removing them from the chassis/PCB. An ESR meter will detect bad electro caps about 99% of the time. The ESR meters are not terribly expensive and usage is similar to a standard digital multimeter. Recommended for anybody that wants to be serious about electronics repair, especially CRTs. If you think you may be recapping more than one CRT in your lifetime, consider getting an ESR meter instead.

like ive seen some burned looking resistors. Also ive seen the ic1 and ic3 can cause a problem similar to the one i saw in this monitor, like partially collapsed, also this model does not have the 50/60 pot, so i guess ill have to get me a groovymame pc with emudrivers in order to have a test machine and start posting some real pictures, but before that ill try to replace the caps.

Although heat scarring can indicate a failure there (or nearby), it is not always a problem as resistors can get a bit hot normally. So test the resistors with your DMM (you should be able to get away without lifting a leg, typically common metal or carbon film resistors fail in OPEN state, though there are exceptions like solid carbon resistors that just slowly get worse).

[abispac]

So today on my wg k7000 19" ,after buying a cap kit, i did most of the bigger caps and let the small ones for tomorrow. I checked most of the stuff Michael Jensen checks on his videos (thanks master for all the great info on your repair videos). Hooked my monitor to my ISO transformer, and the monitor turned on, still with the same problem, as you can see in the picture, the screen seems twisted, this is just the monitor with nothing plugged in, tomorrow ill set up a groovyma… See more

[lilshawn]

probably just a simple as turning your flyback screen control adjustment and/or brightness down. it looks like its turned up too high showing the retrace.

it does not appear to have a neck board transistor issue judged by the color I'm seeing, but it could just be the way you took the picture or how the camera interprets the color... but it is a possibility. Once you have a proper signal fed into it, it should be pretty obvious what the issue is.

get a good CRT test pattern with an SMPTE test pattern or one with some RGB sections on it and see what it looks like. it should become pretty obvious where your issue is and if you have a stuck or missing color.

[abispac]

probably just a simple as turning your flyback screen control adjustment and/or brightness down. it looks like its turned up too high showing the retrace.

it does not appear to have a neck board transistor issue judged by the color I'm seeing, but it could just be the way you took the picture or how the camera interprets the color... but it is a possibility. Once you have a proper signal fed into it, it should be pretty obvious what the issue is.

get a good CRT test pattern with an SMPTE test pattern or one with some RGB sections on it and see what it looks like. it should become pretty obvious where your issue is and if you have a stuck or missing color.

Thanks for the advice, ive been getting alot of help from a facebook group especialy from a guy named Michael Jensen, the twisted problem was the neck being loosed, and the colors was a purity problem, moving the neck solved both problems, then after some adjustments i got nearly perfect picture ,ecept i misiing some focus, so ima finish caping this thing, and if the focus does not get any better  i might buy the flyback to get this bad boy back to new.

[Zebidee]

I don't see anything wrong with your flyback - this looks like a yoke/convergence issue.

Hopefully it is all about the yoke, not the rings. But maybe it is. Adjusting rings is not easy if you don't know what you are doing (read up about it first, watch a YT vid).

Like lilshawn says, you need a proper monitor/TV test image to calibrate yoke/convergence properly, otherwise it is all guesswork. Also helps if you have a large standing mirror, so you can see exactly what happens to the image as you move the yoke/rings about.

[abispac]

I don't see anything wrong with your flyback - this looks like a yoke/convergence issue.

Hopefully it is all about the yoke, not the rings. But maybe it is. Adjusting rings is not easy if you don't know what you are doing (read up about it first, watch a YT vid).

Like lilshawn says, you need a proper monitor/TV test image to calibrate yoke/convergence properly, otherwise it is all guesswork. Also helps if you have a large standing mirror, so you can see exactly what happens to the image as you move the yoke/rings about.

Are you positive about the yoke? Monitor has great image with focus all the way up in the flyback, and with the brightness very very low, it looks great but to dark, as soon as i turn any kind of brigness up, i start to loose the focus. Most monitors i had fixed they never need to have focus in the flyback all the way up. But im also not familiar with this k7000, one thing im allready loving is that, with all weiyah type of chasis, groovymame strugles alot with games like popeye or mortal combat, this k7000 cand handle them just find, so instead of giving up like i always do when a monitor give mes to much trouble, ima try to be patient and fix this bad boy. I want to use it for a dedicated robotro anyway. LOL Anyway thanks alot for any advice on what to look next.  Sorry forgot to mention that, i did reflow the focus cable, i made sure that focus pin looks srtongs and it does, its not bent, and as mentioned before, only good focus is when i have the monitor very dark. Thanks again.

[Zebidee]

Ahhhhhh, now that you mention it like that, I feel less sure about the flyback. However, lowering brightness also makes bad convergence less obvious. You'd want to see some proper test image patterns to be certain. Like at least a white crosshatch pattern to see how your RGB is coming together.

For the Flyback, I guess K7000 flybacks are probably still easily available and not too expensive to swap-out. Not a bad thing to have on hand as a spare too.

If you have a rings tester, also called a Line Out Put Transformer (LOPT) or simply "flyback tester", you can check to see if there are any shorts etc compromising the coils inside your flyback. No need to remove flyback from PCB either. What it does is pumps a short pulse of very low-amp current into the coils which produces a kind of echo, or ringing, in good coils. The meter detects this "ringing" and lights up a row of LEDs. If most or all of the LEDs light up, flyback is good. If none or only a couple of LEDs light up, flyback is probably bad. I have the original Dick Smith flyback tester, Anatek also sell one based on the same design. It is also good for testing other things with lots of coils like transformers and vertical deflection yoke.

If you are interested in getting one of these, I have a few of the original Dick Smith kit versions of both the flyback/rings tester and the ESR meter I mentioned earlier, still in original shrink wrap! PM me if interested. Just a little bit of soldering required. They are very useful for CRT repair and electronic repairs in general.

[lilshawn]

agreed, lower the brightness. having the screen volts up too high makes the picture go out of focus.

don't forget this is a 40 year old CRT monitor...not a modern day display. it's not suppose to output 10,000 lumens of light and have 1,000,000:1 contrast ratios.

[abispac]

agreed, lower the brightness. having the screen volts up too high makes the picture go out of focus.

don't forget this is a 40 year old CRT monitor...not a modern day display. it's not suppose to output 10,000 lumens of light and have 1,000,000:1 contrast ratios.

Well at this point i replaced all caps and checked on the resistors, also fixed a couple of bad traces and nothing seemed to help, my last hope is the flyback as i dont have another tube to test the chasis on to see if the tube is bad. Most Monitors i get my hand into, are inded crap, but the still look bright and clear when fixed,i had had many with badly burnt in, and chinese weiyah chasise and even with that they look bright and crispy, but not this monitor, i got one flyback on the way but it will arribe till the 15th so in the meantime ill have to put this monitor to rest as the others i have... Thanks for your sugestion.

Edit: here a couple of pictures after finishing the caps and fixing some bad traces.

[Zebidee]

Definitely a bit fuzzy, but seems bright enough. Convergence not terrible. You need to degauss the tube, there is an obviously discoloured patch bottom left in pics. Does the monitor have a degaussing coil fitted? Sometimes they need an extra go with a degaussing wand. You can get a cheap degaussing wand online for $10-20, and the YT demos are free! There is a kinda art to it.

Just don't keep the degaussing wand button pressed for more than about 5-6 seconds, as they can melt in your hand.

[abispac]

Definitely a bit fuzzy, but seems bright enough. Convergence not terrible. You need to degauss the tube, there is an obviously discoloured patch bottom left in pics. Does the monitor have a degaussing coil fitted? Sometimes they need an extra go with a degaussing wand. You can get a cheap degaussing wand online for $10-20, and the YT demos are free! There is a kinda art to it.

Just don't keep the degaussing wand button pressed for more than about 5-6 seconds, as they can melt in your hand.

Well over at the face group im getting help, they suspect the tube is bad, and i also have found a few topics on other forums where they found it was actually the tube failing, not even rejuvenating the tube helped, i think it has to do something with bad guns. And im getting a free k7000 flyback , to not discard that problem, but i will have to wait for the 15 for that to happen.   Im also thinking on finding another tube, but being a 7\8 pin tube, is gonna be hard to. Im also thinking on finding a 13 inch tube as ive always wanted a small tube, ive believe this chasis are compatible with  13inch tubes, so lets see if that works, ill keep this topic uptadate it, as i really hate how many but many topics with this similar problem, they never come up with a solution , if there was ever one. By the way, the decoloration problem is just purity problem that gets solved really easy, i just happen to take a picture after playing with the yoke trying to solve the problem.

[abispac]

So I got good news and bad news on my k7000 19". The good news is, the chassis works, it still might need a new flyback but it works. Today I found a 13" Disney tv I was gonna RGB mod, as I always wanted a 13 inch monitor, but then it struck me, that the k7000 19 inch chassis  also works for the 13" inch screen, so after checking the Disney tv has 7 pin to, and the readings in the yoke are similar, so I decided to give it a try, and guess what? I got a 13 inch monitor, it looks nice but the focus it's all the way up, Wich makes me think I still need to change the flyback. Anyway, I'm gonna ask a friend of mine if he can rejuvenate the 19 inch monitor for me, and see how it looks after changing the flyback. The Disney tv I'm still going to RGB mod it and use it as my 13 inch monitor. I'm so exited. The colors in the picture looked better after messing with the pots after the picture.

[abispac]

So to close this, original k7000 tube needs rejuvenating, so im gonna scrap it, the new 13 inch tube looks nice, only issue focus is all the way up, but all other pots are normal, so i might be changing the flyback. Maybe not, if it aint broke dont fix it, lol.

[Zebidee]

Looks good from here!

You got lucky with that tube. If you want to keep the Disney TV, maybe just find a similar donor from a dead TV.

Aside from the neck pins, is a good idea to at least compare, between the tubes, the impedance (ohms) for the horizontal and vertical yokes. This is easy to do with any digital multimeter. Ideally they should be roughly similar.

[abispac]

Looks good from here!

You got lucky with that tube. If you want to keep the Disney TV, maybe just find a similar donor from a dead TV.

Aside from the neck pins, is a good idea to at least compare, between the tubes, the impedance (ohms) for the horizontal and vertical yokes. This is easy to do with any digital multimeter. Ideally they should be roughly similar.

Sorry forgot to mention that i did checked the ohms on both yokes and they where very closed, thats why i gave it a go. Perfect match

[abispac]

Messed up mi monitor, i ended up sending it to a pro for repair, it works just fine now.

[Zebidee]

Was that Michael Jensen? Pleasure to watch, thanks for the link