modessitt
Volunteer: Encyclopedia Submission Moderator
I recently repaired a Spy Hunter boardset in the last few weeks, put it in the game, and it worked just fine. A week later, the monitor is slowly rolling vertically. Adjusting the vertical hold and V-Lin pots can make it slow to almost a stop, but it is with a black line down the center and the left side on the right and the right side on the left. Can't get it to lock.
After looking over some previous threads on this issue, it seems others have had this problem and not found a solution:
http://forums.arcade-museum.com/showthread.php?t=207658
http://forums.arcade-museum.com/showthread.php?t=150650
http://forums.arcade-museum.com/showthread.php?t=212534
http://forums.arcade-museum.com/showthread.php?t=211682
Despite a couple mentions of caps, pots, and IC501 helping some people, these people still didn't have a solution.
Well, I fixed this one, and I'll explain how I did so. It helped that I had a known-working G07 on hand, as I could compare readings. If I hadn't had the extra G07, it's likely I would have chased ghosts for quite a while before solving the puzzle.
As anyone with the G07 flowchart knows, a vertical hold issue is pointed towards three parts - Q306, Q302, and IC501. Now, I had previously used my meter to test these three components and all readings seemed to indicate they were fine. However, when I compared these readings to the known good chassis, I found that the reading between the emitter (black lead) and the collector (red lead) of Q302 showed a different reading. The good chassis showed a reading of 1.4xx, while the bad chassis showed a reading of .7xx. This was the only difference between either chassis. Q302 is a C1685 transistor (which I didn't have new) that cross references to an NTE85 (which I did have new), so I replaced it and the image now locks perfectly.
So, if anyone is still fighting this issue, you may want to go check those readings to see if they are off. if I hadn't had the good chassis, I would have assumed the .7xx reading was okay...
After looking over some previous threads on this issue, it seems others have had this problem and not found a solution:
http://forums.arcade-museum.com/showthread.php?t=207658
http://forums.arcade-museum.com/showthread.php?t=150650
http://forums.arcade-museum.com/showthread.php?t=212534
http://forums.arcade-museum.com/showthread.php?t=211682
Despite a couple mentions of caps, pots, and IC501 helping some people, these people still didn't have a solution.
Well, I fixed this one, and I'll explain how I did so. It helped that I had a known-working G07 on hand, as I could compare readings. If I hadn't had the extra G07, it's likely I would have chased ghosts for quite a while before solving the puzzle.
As anyone with the G07 flowchart knows, a vertical hold issue is pointed towards three parts - Q306, Q302, and IC501. Now, I had previously used my meter to test these three components and all readings seemed to indicate they were fine. However, when I compared these readings to the known good chassis, I found that the reading between the emitter (black lead) and the collector (red lead) of Q302 showed a different reading. The good chassis showed a reading of 1.4xx, while the bad chassis showed a reading of .7xx. This was the only difference between either chassis. Q302 is a C1685 transistor (which I didn't have new) that cross references to an NTE85 (which I did have new), so I replaced it and the image now locks perfectly.
So, if anyone is still fighting this issue, you may want to go check those readings to see if they are off. if I hadn't had the good chassis, I would have assumed the .7xx reading was okay...
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