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| Author | Diagnose blank video output (Read 35942 times) | ||||||||||||||
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DerekLewis
32 MB  Posts: 33 
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on: July 21, 2023, 07:05
Hello, I have a Mac IIci with a recapped mainboard that boots with correct chimes though the onboard video is blank. I bypassed the problem with a Nubus video card, but I would like to diagnose the onboard video, if only to eliminate soldier bridges or a bad cap. |
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wove
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1024 MB Posts: 1363
Reply #1 on: July 21, 2023, 16:18
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Since your Iici starts with its normal bong, it has successfully ran its diagnostics, indicating it has found the onboard video hardware. In my (very) limited experience that indicates the problem is between the video chip and the video out. I would start there, tracing wires from the chip to the video out, could be shorts/broken traces. Check that any capacitors replaced in that are installed correctly. The video out connector (need to look at pinout) should have a plus voltage pin, make sure that has power (probably +5 volts). If that does not have power follow the traces back to known power rail. (It might be easier if there is no power to simply run a bodge wire back to known good power source.)
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Knezzen
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Administrator 512 MB  Posts: 608 Village idiot
Reply #2 on: July 21, 2023, 17:36
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Have you tried the basics like zapping PRAM etc? There might be an odd resolution set on the regular video output.
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3lectr1c
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32 MB Posts: 36 PowerBook Enthusiast
Reply #3 on: July 26, 2023, 23:29
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The IIci's onboard only outputs sync on green video, which only works with monitors that support it. What monitor are you using?
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