• Updated 2023-07-12: Hello, Guest! Welcome back, and be sure to check out this follow-up post about our outage a week or so ago.

Recent content by sgervasi

  1. S

    M5126 Macintosh Portable Sad Mac (0x14/0xCD36)

    I did the bypass SuperSVGA gave above and the board now has 5.2 volts showing at Q16 drain like it is supposed to. The board still won't boot, but it does reliably get to a sad mac with error 03001500 00001FFA - no chime.
  2. S

    M5126 Macintosh Portable Sad Mac (0x14/0xCD36)

    Thanks SuperSVGA - I'll try that bypass and let you know what happens. Let me make sure I have this right: I'm going to jump from comparator pin 18 (V+) to op2 pin 7 (V+) then through 15k or more resistor to comparitor pin 6 (reference V) I guess Q16 is an enhancement-mode transistor?
  3. S

    M5126 Macintosh Portable Sad Mac (0x14/0xCD36)

    The resistors look fine on this board - no damage, no degradation. It seems as though this hybrid board is bad but I certainly don't want to replace it without being sure. SuperSVGA has good knowledge but I know it's hard for him without seeing the board. I know pin 8 is supposed to send...
  4. S

    M5126 Macintosh Portable Sad Mac (0x14/0xCD36)

    Here's the results with all 4 pins on J17 connected to the battery and with the power supply connected: Right after I reconnected the battery I read 1.22V on the comparator green pin, .06V on the red pin, 7.51V on the yellow, and the blue pin now reads battery voltage at 6.45V the op amp to the...
  5. S

    M5126 Macintosh Portable Sad Mac (0x14/0xCD36)

    it's currently connected to J17 pins 3 & 4
  6. S

    M5126 Macintosh Portable Sad Mac (0x14/0xCD36)

    The board is on the table with only the battery connected to one side of the molex connector. Does the 6V battery need to connect to both positives in that connector?
  7. S

    M5126 Macintosh Portable Sad Mac (0x14/0xCD36)

    I should mention this board doesn't turn on at all - no chime, no video. After I recapped it I could get a sad mac intermittently by doing different things - unplug/re-plug the keyboard, then it quit all together just like before I recapped it.
  8. S

    M5126 Macintosh Portable Sad Mac (0x14/0xCD36)

    The V+ (yellow) shows 7.51V with the power supply connected and battery voltage 6.44 when it's not on the comparator the red pin shows 0V, the green .09V - the blue highlighted pin is at .02V when I connected the 9V battery to the left side + and - pins on the molex the voltages change - red...
  9. S

    M5126 Macintosh Portable Sad Mac (0x14/0xCD36)

    Thank you for taking the time to give so much detail! I checked the voltages and at Q16 pin 1, and at pin 8 on the hybrid I get .10 volts (pins 2 and 3 on Q16 read 7.36V) I see 0 volts on the yellow highlighted pin on the op amp in the last picture The green highlighted pin shows .18V, the red...
  10. S

    M5126 Macintosh Portable Sad Mac (0x14/0xCD36)

    How can the full Battery voltage 6.45V get to the +5 rail on a macintosh portable non-backlit? Also there is no -5 volts showing on pin 33 of the hybrid board
  11. S

    M5126 Macintosh Portable Sad Mac (0x14/0xCD36)

    Does anyone know how the Macintosh portable non backlit logic board generates 5V? I can't find 5V anywhere - only 12V and 6.5 and 7.5. A fully charged 6V (reads about 6.5V) battery is connected. The board has been recapped and it won't boot at all - no video no chime
Top