androda
Well-known member
My friend asked me to fix up his old Portable and I'm giving it a shot. Done capacitor replacement jobs before (several), and replaced the capacitors with very few issues. There were a few traces where the cap goo was clearly under the soldermask, so I scraped off the mask, cleaned up the goo, plated with solder, and then covered with new mask. Things generally look good, though I haven't done an ultra-close inspection on the entire board. Some pins on the video chip (top center pins) needed rework because of corrosion, and a few other things here and there like those tiny transistors.
Now, on to the behavior. Often, the Portable starts without a problem. Happy mac, successful boot. This is both on battery and on battery + power adapter. I am using the correct Portable power adapter, the battery is fresh, and the switch by the battery is pressed down. Oh, and it has a 9V battery too.
5v "always on" rail is solid at 5.2 volts. 12v line is also solid, at 11.85 volts. Power manager chip is getting its 3.9 MHz clock signal. Hybrid ADC line varies between 1.76 volts and 4 volts, with battery voltage being 6 volts and 7.1 volts respectively.
Sometimes, the Portable does not boot up, and just freezes at a screen of nothingness or garbage lines near the top of the screen. Other times it has looked like the screen image here:
There have been some sad mac codes here and there. A few examples (first line / second line):
05000706/00001FA7
01000700/00001FFA
01000314/00001FF4
A few times on startup the floppy drive has made the classic 'disk read' sound with nothing in the drive, and a failed boot. Hard drive never starts up, either nothing or random garbage on the display.
Based on the thread I linked above, it could be the SWIM chip that's going out. Are there any good methods to check this, other than pulling it off the board?
What other power manager signals or voltage rails should I watch? I was planning to monitor the 68000's clock signal, halt and reset lines, IWM_CNTRL, SCC_CNTRL, STOP_CLOCK, etc. Speaking of these signals I've noticed some have a dot next to them (on the schematic). Does this mean the signal is 'on' or 'active' when the voltage is high or low?
Often, when the system fails to boot, pressing the reset button a few times (press, wait a few seconds, press again...) will end up clearing the problem and I get happy mac successful boot.
Other than that, it seems the system struggles to start after it's been sitting for awhile. Going from no batteries at all, put in the batteries and cover, it starts right up. Wait 6 hours, crash.
Thanks for all your help, this seems to be "the place" to come for the Macintosh Portable. I'm hoping to get this old mac up and happy, it was apparently the first computer my friend ever purchased with his own money.
Now, on to the behavior. Often, the Portable starts without a problem. Happy mac, successful boot. This is both on battery and on battery + power adapter. I am using the correct Portable power adapter, the battery is fresh, and the switch by the battery is pressed down. Oh, and it has a 9V battery too.
5v "always on" rail is solid at 5.2 volts. 12v line is also solid, at 11.85 volts. Power manager chip is getting its 3.9 MHz clock signal. Hybrid ADC line varies between 1.76 volts and 4 volts, with battery voltage being 6 volts and 7.1 volts respectively.
Sometimes, the Portable does not boot up, and just freezes at a screen of nothingness or garbage lines near the top of the screen. Other times it has looked like the screen image here:
There have been some sad mac codes here and there. A few examples (first line / second line):
05000706/00001FA7
01000700/00001FFA
01000314/00001FF4
A few times on startup the floppy drive has made the classic 'disk read' sound with nothing in the drive, and a failed boot. Hard drive never starts up, either nothing or random garbage on the display.
Based on the thread I linked above, it could be the SWIM chip that's going out. Are there any good methods to check this, other than pulling it off the board?
What other power manager signals or voltage rails should I watch? I was planning to monitor the 68000's clock signal, halt and reset lines, IWM_CNTRL, SCC_CNTRL, STOP_CLOCK, etc. Speaking of these signals I've noticed some have a dot next to them (on the schematic). Does this mean the signal is 'on' or 'active' when the voltage is high or low?
Often, when the system fails to boot, pressing the reset button a few times (press, wait a few seconds, press again...) will end up clearing the problem and I get happy mac successful boot.
Other than that, it seems the system struggles to start after it's been sitting for awhile. Going from no batteries at all, put in the batteries and cover, it starts right up. Wait 6 hours, crash.
Thanks for all your help, this seems to be "the place" to come for the Macintosh Portable. I'm hoping to get this old mac up and happy, it was apparently the first computer my friend ever purchased with his own money.
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