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  1. You will probably have to remove the regulator from the board to test it, otherwise you may see the effects of other capacitors between either the input rail or output rail and ground giving you an impression that there may be a short. The exploded capacitor on the input rail pin is there to provide some stability for the voltage regulation, but there may be enough additional capacitance on that voltage source that it could just be removed and it would still work ok as Unknown_K stated.
  2. Looks like it is a tantalum capacitor that is associated with that three terminal 7805 5V regulator next to the failed cap. From the marking on the cap it is a 10 uF 6V part. I'd replace it with a 10V or 15V part if you can find one to give a safety margin.
  3. Wonder if they are the Pinnacle Micro "Gold Card", which was a disk compression processor. I found this bit of text in a search for "pinnacle micro nubus": Compression boards put the speed on squeeze: Sigma's DoubleUp and Pinnacle Micro's Gold Card being near-instantaneous compression to Sigma Designs Inc's DoubleUpand Pinnacle Micro Inc's Gold Card file compression boards provide compression without data loss, avoiding speed problems found in boards that employ loss-prone compression. These boards have fast enough compression and decompression speeds that users can keep most of their files in a compressed format. Sigma claims that its DoubleUp works eight times faster than software-only compression and offers an average ratio of 2-to-1. The board comes with DiskDoubler software that lets users select and compress a hard disk from the desktop. Pinnacle Micro Inc contends that its Gold Card can expand disk capacity by two to seven times. The product compresses and decompresses 20 times faster than software-only compression. Both cards run on Mac II-family microcomputers. DoubleUp is currently available and Gold Card is expected to ship in late April 1991.
  4. WIth all that fast SRAM on the board and no I/O connectors, I'm guessing the square unmarked chip in the corner is meant to offload some kind of processing function.
  5. Can you see if there is a 3.58 MHz clock signal at pin 23 of the 8530 chip? Maybe there is a bad solder joint there. That clock signal is output by the Mega2 chip, and if it did not make it to the 8530 SCC, the register writes and reads wouldn't function correctly. If the Mega2 chip wasn't outputting the 3.58 MHz clock, then the entire IIgs might not work correctly.
  6. According to a ROM source listing found at https://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Computers/Apple%20II/Apple%20IIGS/Documentation/, the serial I/O chip test failure code 01 indicates a problem with the SCC register R/W test, which is testing some of the channel A and channel B registers. It tests registers 2, 12, 13, and some of the bits in register 15. Unfortunately it doesn't indicate which of the registers may have failed the test. The test appears to test all of the bit combinations in the registers. I'll have to experiment if the diagnostic disk images provide any more detailed tests for the SCC.
  7. Is it just the diagnostic disk, or a mini diagnostic built into the ROM or a report from GS/OS? Is it possible to just ignore the error report, or does it get in the way of running programs?
  8. Seems to me like you should be able to disable the on-board serial ports and use a card, the ROM slot configuration menus should work for that. Unfortunately I don't have a serial card to try in my ROM 01 IIgs.
  9. Unfortunately it looks like it might be hard to find those chips. Mouser has the 40 pin version listed in stock, but not the 44 pin version you'd need.
  10. Have you checked for leaking capacitors or bad solder joints for the serial chip? Maybe the issue can be resolved with a simple fix. Also, have you downloaded the IIgs Diagnostic disk images? I have three versions, one of the version 3 variants might tell you something more.
  11. cruff


    I used to run A/UX on my IIsi years ago. It worked fine for what it was. I gave my IIsi away, but still remember it fondly. I wish A/UX would run on my Quadra 631.
  12. cruff

    SCSI2SD daisy chain

    Only termination power is available on a standard SCSI interface, including the 25-pin Mac variety. You should not expect to be able to power the SCSI2SD from that, let alone two of them and the required terminator.
  13. cruff

    DIP switch settings for Mac to VGA adapter

    I see the link. It shows settings for the Viewsonic adapter AC-AT Mac II-02, which presumably was meant for a Mac II era system. For 1152x870 resolution SW 1-4 are all on. SW 5-8 depend on the sync method required by the monitor. Sync on Green 5-8 all off.
  14. cruff

    Extended Keyboard II troubleshooting

    Is it not sufficient to remove all of the keycaps then the plate? It is a minor pain, but you should then be able to remove the metal plate and clean up some more.
  15. Wait, made a mistake, 11.32 V divided by 1 Kohm gives 11.32 mA. If you multiply 11.32 V by 11.32 mA you get 128 mW, which would exceed the rating of the pot by a bit. You might see if you can find a trim pot with a higher power rating.