k7000 vertical wrap

bluestreak

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New at the monitor board repair, so I think this is what's happening. see pic.

I put in a new cap kit as this problem existed prior. Cap kit fixed it but after running it for a few hours, I was about to consider it a done deal and prep it for the "arcade room".
Suddenly problem returned.

Searched threads an found that C51 could be an issue or IC3 possibly.
I haven't checked those so far, but posting to see if there are any other ideas or anyone else that may have had this issue while I have it pulled back out tomorrow (today).

Thanks,
Mike
 

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Search over the entire thing for solder issues, especially with those big power resistors near the HOT.

Have you tried adjusting the 50/60-Hz pot to see if it affects it any?
 
I had resoldered the larger connections when I put in the cap kit last week and looked over the others but will take another look if I have to remove it from the chassis again.

I have not tried the 50/60 HZ pot adjustment, but will. I assume this POT is noted as HZ adj somewhere on the board?

Just strange, it worked great for a couple of hours, but not now, even after it has been off for 30 minutes or so for a cool down. Didn't try it this morning before leaving to see how it acted but wil this afternoon.
 
desolder and resolder r101 and other large resistors in that area..


actually fully desolder r101, scrape the legs, verify it hasnt changed value, check the solder pads on the board as sometimes they turn black and need scraped off, then reinstall and resolder the resistor.


not saying thats it but 9/10 thats it

also wiggle all large transistors resistors diodes to verify you dont have a cracked solder connection...


good luck!! hope ya fix it!
 
Does shutting it off and letting everything cool off for awhile make the problem go away for a little while ?

I've seen similar issues fixed by adjusting the 50/60Hz pot (tiny pot by the Horizontal Hold pot on the back of the chassis)
BUT... the way the graphics are separating has me a bit confused, never seen it do it quite like that.
 
I just rebuilt a 25" K7000 that did the same thing. Adjusting the 50/60-Hz pot made most of the lines go away. three days later the monitor was dead again. Found a pad had separated from a trace right on those power resistors that I reflowed. Added a jumper and it's back up and doing fine...
 
Worse one I have seen separate the image like that was only about the first inch or so.
(which would adjust out easy enough)
That one just kinda stuck out to me as being really bad.
 
Does shutting it off and letting everything cool off for awhile make the problem go away for a little while ?

I've seen similar issues fixed by adjusting the 50/60Hz pot (tiny pot by the Horizontal Hold pot on the back of the chassis)
BUT... the way the graphics are separating has me a bit confused, never seen it do it quite like that.
Thought cooling down may work also but after being off for nearly 24 hrs no change. I tried the 50/60 pot (sure don't like it being so close to the high voltage trans for personal reasons) but no chnage in the roll over.

Going to repull the board and check all solder connections again and the suggestions about R101,etc.

I hope this doesn't turn out to be a bear of a problem to find.

Thanks for the suggestions and I'll post how it goes.
 
Well, looked good when I put it back in again tonight......initially....

Looked at all connections with Magnifying glass. There were a few suspect connections including the R101 so I cleaned and resoldered. Touched up many others just to be sure.
Checked diodes and appeared OK.
Transistor connections didn't appear loose but they were resoldered as well.
Put it back in and looked good except for some retrace lines when I turned up the black level (made it darker).
Started a game and not 2 minutes into it, here we go again. Same problem.

There are 4 non-electrolytic caps that haven't been replaced with the cap kit. C4,5,6 and one I don't remember the other one on a stand off board. Could these be causing a problem? I left the K7000 schem at work that I downloaded today so not sure what circuit they are in and really need to get some rest tonight so am not going to search internet tonight.

One last question, if it may not be the remaining caps, can a vertical output trans do this?

Thanks guys, really need to go get some sleep now for tomorrows work day.
 
Update- this morning before leaving for work I turned it on and it looked good except for retrace lines, which if memory serves me right is because high voltage is turned up too high.
So i'm thinking I either have another cold solder joint or a component on the verge of failure.
I have a spare CPU board that I will swap out tonight to make sure the sync coming into the monitor chassis is not the failing culprit. I want to make sure I am chasing the problem in the correct area.
If it turns out to be on the monitor chassis, then looks like I will be replacing some additional parts, but at least I can be sure I am working on the correct board.
 
Just to close out the thread...most may have considered it closed already. :)
This afternoon I found that there is a bad connection somewhere on the video/sync input cable, or near there.
I can tap the daughter board on the chassis or press on the video input cable and problem clears up for awhile,but comes back.
Feeling better about it now since I at least know the area where the problem exists and will eventually find it.

Thanks again for all the input, it helped eliminate what wasn't the problem.
 
reflow the solder on the pins where the video wires hooks up.. at least you know how to break it now lol itll help ya track it down..
 
reflow the solder on the pins where the video wires hooks up.. at least you know how to break it now lol itll help ya track it down..
I had did that earlier on. Just found the problem (waiting on iron to heat up). The little stand off board that has L600 and R618, plus a few other parts, has bad solder joints on it's pins. I couldn't see them while it was plugged into the main board, but once off, it's obvious.
I picked a good one to learn on, but I did learn a bunch.
 
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