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Showing results for tags 'trace'.
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So now that I've gotten my hands on a Macintosh SE/30 to fix up, I went and checked the seller's conclusion on what was wrong it. According to him, the CRT wouldn't come on, and he suspected the analog board. To put that theory to the test, I swapped boards between my working SE, and the SE/30. The SE in the SE/30 chassis booted, and was happily driving the CRT. Thus, the issue was not with the SE/30 analog board or CRT. And to be expected, the SE/30 totally failed to boot in the SE chassis. The seller thought the SE/30 didn't chime because the speaker cable wasn't plugged in, but his memory failed him because it was firmly plugged in. So, now that the SE/30 board is definitely the culprit, I decided to give the board a good look over. And would you believe it, there was a broken trace (open the image for the full resolution): The jumper might obscure it a bit, but it connects from a pin from the UI6 to a pad that continues to a trace that is completely dug out just below the UG7 chip. On the underneath of the board, the pad doesn't have any connections to any other part of the board. What I can't figure out however is what the jumper cable is supposed to do. The schematic I was looking at made it seem that that pin on UI6, which is the PAL HSync chip from what I can find, isn't used for anything and not connected to anything. So why is it jumpered, and how does it influence the way to system works? I can't quite find out where the trace goes to, it goes underneath the GLUE chip and from there on out it's anyone's guess if it connects to the GLUE or goes elsewhere. Now, I knew the caps were highely likely bad, and some pins of chips near the electrolytic capacitors looked a little dull, so I gave it a bath of warm soapy water followed up by some 96% cleaning alcohol, then I left it to dry. After drying, it managed to display a bunch of dots across the upper section of the screen for a while, which started to disappear one by one, to now just showing a very, very faint grey image with lines going across it horizontally. So the question is, is this the result of bad capacitors, or that bad trace? And if it is the trace, where does it go?