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doctormistral

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  1. After some work i got this behaviour when turning on the mac: Quick checkerboard -> Sad Mac with stripes --(after a while)-> Vertical patterns. Any suggestion about the cause or about what to check? 20200709_211825.mp4
  2. Hi all, what are the differences between 820-0390-A and 820-0390-B models of Mac Classic Logic Board? Are they interchangeable? Thanks
  3. Any other suggestions? Would it be worth buying an inexpensive logical analyzer to check what is going on on the board?
  4. Hi marcelv, yes, I removed the battery holder at least twice to check the board, no problems. Recently I've also checked frequencies of CPU 7.8Mhz and 32.768 on RTC crystal and they are there.....
  5. Hi @marcelv, yes, I removed the battery holder at least twice to check the board, no problems. Recently I've also checked frequencies of CPU 7.8Mhz and 32.768 on RTC crystal and they are there.....
  6. I've just replaced 2 x 74LS245, 1 x 74LS174 and 2 x 74LS257 but unfortunately there has been no change..... so sad Screen with RAM board installed Screen without RAM board installed
  7. I made my Mac Classic working with SCSI2SD V5.1. The most important thing to check everything is compatible is to start with a bootable disk with System in the partition 0. I suggest you to use already made images from here, better use the 7.5.5 image. I used dd command to copy image to the board, no need to connect power supply to the board. Once connected the board to the SCSI cable the mac boot at first attempt. If you need to inspect scsi drives with HD SC setup you have to get the fixed one because the original is locked to Apple signed disks. Hope this helps
  8. Normally connecting a Mac Classic (working) logic board to only its Molex connector (so no ram card, no floppy, no disk), it starts with sound and showing the floppy with question mark on the screen. Now, I'd like to know which components of LB are (not) participating in this phase in order to concentrate on them (or exclude them) in my tests to understand why it does not start. Thanks for suggestions.
  9. Hi, I successfully used SCS2SD 5.1 with a Mac Classic. Starting using the image provide in http://www.savagetaylor.com/wp-content/uploads/68k_Macintosh/Bootdisks/OS_755_2GB.zip and copying it with dd command (available for mac and win) it booted at first attempt! And no need to plug the card to the 5V. The only cases where i got the Disk? icon was when, by mistake, I tried to boot from a not-bootable partition 0 (zero) so use the link above with OS 755 (works also with 6.08). Also the Mac Classic is not listed in the compatibility list but however it works.
  10. Hi all! I'm from Italy and I'm trying to recover a mac classic logical board that I've previously recovered after a Max bomb in 2012. After a full recap and a lot of cleaning the mac has come back to life but after a while a put it in a box and kept it until 2017. Than i did a check and it was not working anymore but i decided to kept it in the box because no time to dedicate to it. In these days of lockdown I decided to fix it but it appears much harder than expected! Latest Symptoms: chessboard video (sometimes messed), regardless (with or without) ram ex
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