68kMLA Classic Interface

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Color classic AV recap booted first time fine
Posted by: thegarse on 2020-12-11 22:42:58
Hi everyone, I did the painstaking analog video recap on my color classic verified polarity multiple times and thought I was in good shape because the computer booted up without any issues. Today I booted the Mac again and got a bouncy pin cushion shaped image that looked like it was shifted to the right a bit. I scratched my head because it works fine the night before so I took the analog video board out double checked for broken joints, reflowed a few that looked suspect, rechecked the polarity and booted it again, this time I got less video and saw a plume of smoke and immediately  I turned off all power to my workbench. Upon inspection it looks like the plume of smoke may have come from RL54 a 330 ohm resistor that currently measures at 33 ohms (pictured). Replacing the resistor seems pretty simple but I wonder if there is more of a backstory to this issue and I’m curious if anyone has seen it. Thanks.

FA9C1F34-B367-4F03-9529-48E8814AB2E6.jpeg
Posted by: thegarse on 2020-12-12 19:44:28
I found one doc that said RL54 should be a 33ohm resistor: https://powercc.org/640x480/

a few others state 330ohm, can someone give me a definitive value?

Based on the color code of the original I see it as a 33ohm, I’m not a pro at reading color codes btw. Also will a cooked resistor measure the appropriate ohms?
Posted by: thegarse on 2020-12-23 11:55:56
Hi all got my resistors in. What would be the best place to start 330ohm or 30ohm? 🙂

044EDBB0-5E30-4E8A-AE2F-30E7B39FDF58.jpeg
Posted by: thegarse on 2021-01-01 08:11:10
Well, I tried the 330ohm, and it also smoked so I turned it off. I think now I will try to disconnect as many things as I can and add them one at a time. I do have a AV board for a performa 579 so I can poach some parts but because it was a bigger screen a lot of items will not transfer. I'm guessing a short?
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