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Wg k7000? Bad focus, or dim picture (solved)
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:
--- Quote from: Zebidee on November 02, 2021, 06:44:48 pm ---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.
--- End quote ---
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:
--- Quote from: lilshawn on November 03, 2021, 02:13:27 pm ---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.
--- End quote ---
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.