sanyo 20-Z2aw image shifted 1/3 to right

G.E

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Hi,

My first post to KLOV!

I'm trying to solve a CRT issue on my Punch-out!! While running over the weekend, the image on the lower monitor has shifted to the right about 1/3-1/2 of the screen. There's no image distortion, blinking, folding etc. It looks completely normal except it's shifted. In fact since everything happens in the middle of the screen for this game, it's still completely playable.

Adjusting Horizontal Center (VR352) shifts the center of the image, but the border of the image does not shift left, the 1/3 is a hard stop. Difficult to explain but it's clear in the video below. The monitor is connected to the Crafty TPG. The blank area is at the bottom in the video as the monitor is sitting sideways.

A Cap Kit was installed in 2021, and it has been working fine for the last few years. Checked all the resistors and caps around IC401 and everything seems fine. Checking all the components around the horizontal drive circuit has turned up nothing.

Hooking the scope up shows proper wave forms as shown in the schematic.

B+ is another story and drifts significantly above and below 108V. I've ordered a new regulator (IC401) and pot (VR601).

I also ordered a new flyback and IC401; even if these are not the issue, they can be kept for future use.

I haven't taken the upper monitor out yet to compare signals etc., but that may be coming soon.

Any ideas would be greatly welcomed,

Greg


 
Does the game board and the TPG have about the same offset from the bottom (left if monitor was horizontal) ?
 
Solved.

For anyone who has a similar problem since I couldn't find this specific issue with forum searches:

  • Watching Mikes Amateur Arcade Monitor Repair channel and searching for horizontal shift issues clued me in; look for capacitors related to the horizontal width coil
  • Found bad C485 (0.047uF 100V mylar); it showed evidence of overheating over the years and is tucked away against one side of the Flyback
    • Amazingly found some NOS units in a bag; replaced and monitor almost normal
    • Image is slightly over-shifted from previous condition and can't be completely corrected with position pot, but image is completely usable
  • Found C470 (0.47uF 200V mylar) out of spec at 0.33uF
    • This is likely why the screen is still not able to completely center, but the surplus electronics shop is closed til tomorrow
    • could also be flyback?
  • Regarding voltage:
    • 20EV and 20-Z2W are 100VAC, not 115vAC (found during forum search, and also clearly labeled on monitor and specs document) DUH
    • Variac in combination with iso-transformer resolved all B+ issues
    • No need to change voltage regulator
Greg
 

Attachments

  • 2023-07-09 14_26_27-Sanyo_20Z2AW_Schematic.pdf - Foxit PDF Reader.png
    2023-07-09 14_26_27-Sanyo_20Z2AW_Schematic.pdf - Foxit PDF Reader.png
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  • 2023-07-09 15_21_05-Greenshot capture form.png
    2023-07-09 15_21_05-Greenshot capture form.png
    3.7 MB · Views: 9
  • IMG_3683-resized.JPG
    IMG_3683-resized.JPG
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I think the EZY was the 115V model, was in Atari games if I'm not mistaken. I've never actually encountered one of those, only ever saw the Sharp XM-2001s in those games.
 
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