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Everything posted by LinemanDoc

  1. I recently was given a number of antique computers from a friend including several Macs. I was removing the capicitors off one of the SE/30 logic boards and noticed that it has some sort of repair or modification on it. A trace has been deliberately cut and a jumper wire has been soldered on directly to another component. I realized that I'm not the best at reading circuit diagrams (but I'm learning) and I wanted to ask if anyone recognizes what is going on here. My current plan is to simply assume the person who did it knew what they were doing and ignore it. Once I get new c
  2. I just wanted to update this thread with some kind of resolution in case anyone reads this later and wonders what happened. I ended up finding a complete replacement logic board, recapped that, and got it running. I donated this problem board to another forum member who I am sure can put it to good use. Hopefully he is able to fix it and his post results on this thread, but I can't speak for him. Thanks davidg5678 and others who read this. I learned alot from your tips.
  3. I downloaded the redrawn schematics and they are much easier to read. Thanks to everyone who helped with that project. I have the last week of the month off of work and will have the time to tediously check every trace that involves the ROM and RAM or is simply near the leaky capacitors.
  4. Voltages were good at the floppy connector. All the capacitor pinouts also good, except I believe the chart has C1 polarity reversed. My board has C1 negative terminal going directly to ground and + goes to J12 pin 12. I believe it to be an error in the chart and not my board.
  5. Thanks for the reply. I have already checked the ROM pinouts using the following image from https://ronangaillard.github.io/posts/my-mac-se30-is-back-alive/ and they have continuity to the corresponding Motorola CPU pins. I also checked the ROM pins to themselves to verify that there are no shorts between pins. I will use your posted images to check the capacitor pinouts and voltages tonight when I get more time. Is it normal to have a split second beep from the continuity tester when first touching VCC to GND? .
  6. This is my first post and first Mac restoration project. I was given a Mac SE/30 that had been put on a shelf display and not used for 20 years. It had the simasimac problem and no startup tones. I removed the logic board and saw a few corroded spots from leaky capacitors, but overall, the board looked clean. I washed it with soap, water, and a toothbrush. Then I soaked it in 99.9% rubbing alcohol for 30 minutes and brushed and rinsed with alcohol again. After drying it for a few days, I replaced the capacitors with the tantalum capacitor kit from console5.com. I have only a little sold
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