K7500 issue, snow/static & H pos effecting brightness

italie

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K7500 issue, snow/static & H pos effecting brightness

Hello all,

Been a while since I've pulled apart a K7500, having issues with "artifacts" on one. Running from a silent scope 2, medium res. The monitor has been fully capped at this point, the neck board transistors addressed and re soldered. Here are the issues I'm seeing.

- Snow or static on the screen around letters. Almost like a pixelated smearing. Text is hard to read at times. Picture can look perfect in some spots.
- Faint white noise/groups of lines rolling across the screen (not raster lines). Kind of like an old TV with the rabbit ears out of adjustment
- H pos pot on the remote board works, but the picture dims when moved from either side of "center".
- H width pot does not work.


I want to say I've seen this issue before, and the issue was that remote mounted transistor. I didn't have another chassis or part handy to swap it out tonight and test that theory. Looking at the schematic though, I'd guess the issue is more around U701

Any thoughts?


Thanks in advance.
 
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i had a u5000 that some of the adjustments would not work. it would eat hots too about every 8 hrs of runtime. On mine the mosfet was not remote mounted, but they were later on i guess. Ohm between the center and rightr leg of that mosfet. If you get anything under 100 ohms, its shroted and bad.
 
Hello all,

Been a while since I've pulled apart a K7500, having issues with "artifacts" on one. Running from a silent scope 2, medium res. The monitor has been fully capped at this point, the neck board transistors addressed and re soldered. Here are the issues I'm seeing.

- Snow or static on the screen around letters. Almost like a pixelated smearing. Text is hard to read at times. Picture can look perfect in some spots.
- Faint white noise/groups of lines rolling across the screen (not raster lines). Kind of like an old TV with the rabbit ears out of adjustment
- H pos pot on the remote board works, but the picture dims when moved from either side of "center".
- H width pot does not work.


I want to say I've seen this issue before, and the issue was that remote mounted transistor. I didn't have another chassis or part handy to swap it out tonight and test that theory. Looking at the schematic though, I'd guess the issue is more around U701

Any thoughts?


Thanks in advance.

Replace C729 the 10uf 50v NP

If the width pot And the Darlington power transistor is good replace the cap.
 
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