I got a Megatouch game from my uncle to fix up and return to him. It had several issues:
1. Screen was displaying too wide, horiz width controls did nothing
2. A light zig-zag line would be evident throughout the screen after the monitor was left on an hour or so, eventually this would be bright enough to make it unplayable
3. Colors were WAY off in the corners, see attached pic.
First off, I got a cap kit from Zanen for the Megatouch monitor I was using. The kit arrived but some of the cap values were WAY THE F off from the caps I was pulling out of the boards. Put the project on hold until I could visit the local grognards to get some more caps. They told me that in some cases it was fine to have a different cap level (for monitors anyway) than what was in there, so long as they weren't too far off. They weren't just referring to voltage (which I already knew, higher than what's listed is okay), but to capacitance as well. They also suggested that Zanen may have gone through the schematic and determined that it would still be in spec if they put in the caps they did.. or they could simply have had a ton of one type on the shelf and said 'good enough'. Without contacting Zanen, I've no idea, but I would rather be safe than sorry. The only cap I put in that did not match what came out was the non-polarized 4.7uf @ 50V (C19). The cap that came out was a 5.6uf @50V. I replaced with the Zanen cap.
This fixed the issue with the horizontal width not being adjustable. I can now change the size as normal.
Issue 2 - monitor too bright. I played with the brightness and contrast controls and couldn't resolve this. Then I looked at the sticky on this forum and found there's a "SCREEN" control on the flyback. I adjusted this and the too-bright situation went away. However, I discovered Issue 3 at this time.
Issue 3 - colors separated on edges of monitor. This was a weird one. I thought perhaps I had some convergence adjustments to make, and was ready to punt this to a pro. I had tried to adjust the "FOCUS" control but it was glued stuck to a position so I didn't try it again. Tried a degauss coil, no effect, so then I thought, let's mess with the R-G-B drives. Got out a nice screwdriver and adjusted them, no effect on my issue. BUT, the screwdriver was something I had not tried on the "FOCUS" control yet, so I put it in and started turning up the pressure until it let me adjust it. Sure enough, this resolved the issue!
1. Screen was displaying too wide, horiz width controls did nothing
2. A light zig-zag line would be evident throughout the screen after the monitor was left on an hour or so, eventually this would be bright enough to make it unplayable
3. Colors were WAY off in the corners, see attached pic.
First off, I got a cap kit from Zanen for the Megatouch monitor I was using. The kit arrived but some of the cap values were WAY THE F off from the caps I was pulling out of the boards. Put the project on hold until I could visit the local grognards to get some more caps. They told me that in some cases it was fine to have a different cap level (for monitors anyway) than what was in there, so long as they weren't too far off. They weren't just referring to voltage (which I already knew, higher than what's listed is okay), but to capacitance as well. They also suggested that Zanen may have gone through the schematic and determined that it would still be in spec if they put in the caps they did.. or they could simply have had a ton of one type on the shelf and said 'good enough'. Without contacting Zanen, I've no idea, but I would rather be safe than sorry. The only cap I put in that did not match what came out was the non-polarized 4.7uf @ 50V (C19). The cap that came out was a 5.6uf @50V. I replaced with the Zanen cap.
This fixed the issue with the horizontal width not being adjustable. I can now change the size as normal.
Issue 2 - monitor too bright. I played with the brightness and contrast controls and couldn't resolve this. Then I looked at the sticky on this forum and found there's a "SCREEN" control on the flyback. I adjusted this and the too-bright situation went away. However, I discovered Issue 3 at this time.
Issue 3 - colors separated on edges of monitor. This was a weird one. I thought perhaps I had some convergence adjustments to make, and was ready to punt this to a pro. I had tried to adjust the "FOCUS" control but it was glued stuck to a position so I didn't try it again. Tried a degauss coil, no effect, so then I thought, let's mess with the R-G-B drives. Got out a nice screwdriver and adjusted them, no effect on my issue. BUT, the screwdriver was something I had not tried on the "FOCUS" control yet, so I put it in and started turning up the pressure until it let me adjust it. Sure enough, this resolved the issue!
