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The Duo 270c does have a standard 8 pin modern port which you should be able to use for localtalk. But that's it, no floppy drive or anything else without a dock. Internal hard drive is scsi, so you're looking at scsi2sd or similar. LC III has a slower CPU and system bus, but you can add an...

Which voltage regulator card is in your beige G3? I've heard that one from Royal Technology can misbehave with certain ZIF upgrades, possibly causing damage. If you have the Switch Power or Raytheon voltage regulator card, you should be fine.

No other capacitors found with this issue.  Guess I just lucked into it while poking around at the power manager test port.  After patching up the connections to C116, no difference in behavior.  Starts right up after power is connected, but fails 3/4 times after sitting for awhile with...

You can also steal full screen assemblies from the 5300. My 190cs's dual scan color is getting replaced with 5300c's active matrix color (same resolution). You just need the full display cable, going all the way to the motherboard.

My freakish workaround was to format the SD card in the SD-IDE adapter in OS X as HFS, then the 7.5.2 disk utility boot disk told me it needed to be initialized and now it no longer says the SD-IDE adapter is locked.  Thus the installer lets me select the SD-IDE adapter as the install...

I'm trying to use an SD to ide adapter as the hard drive in my 190, and it's been a pain. Had to install it in my Wallstreet to format as HFS, but now the system 7.5.2 installer (floppy) tells me the disk is locked (despite having literally just formatted it in my Wallstreet with no issues). At...

Another issue found.  C116 (by the power manager side keyboard/trackball connector) was very nearly electrically isolated from the traces it is sitting on.  Visually the traces look fine.  Green, not dark or discolored or anything.  Pads look fine, nice and shiny tin.  But when I checked with my...

Today I spun a little adapter PCB that converts the 2x25 1.27mm pin headers for the EPWRMGR test connector out into two 1x25 2.54mm pin headers.  Also ordered some 1.27mm male and female connectors for the PCB and board.  Figure I'll solder a female connector on the board (gotta clean the solder...

Yes indeed, the capacitors will leak whether they were actually powered up or not.  So NOS parts, still sealed, never used, stored properly... can still come right out of the bag with capacitors leaking and corroded traces on the board.  Sigh.

Could be capacitors, could be battery leakage. These old 68k laptops often need capacitors replaced, with the leakage causing potentially a lot of random issues.

Very nice, I have been wondering on the status of ardscsino and forks.  This seems like the best low-cost scsi replacement for older devices, where speed is less of a concern.  Good work.

The original dexcool was more or less terrible. Newer versions of the formula are much improved, I just don't know whether they are directly compatible for mixing.

Seems like the consensus is basically that the power manager chip is having issues then.  I had the thought "too bad I don't have a logic analyzer, that would help me characterize exactly the difference in behavior of the chip between a good boot and a failed one". So I hopped on my local...

Ah, so those mosfets are used as linear regulators thanks to their variable resistance.  Being used to more modern electronics, I just expected these to be buck regulators.  Makes me wonder whether an LDO buck would work here.  So maybe instead of reverse engineering the hybrid's design we...

Thinking on the subject of buck regulators some more, there has to be at least one, and likely more.  How else do you take 6 to 7-ish volts from the battery and turn it into the 5 volt power rail? Looks like  Q16 is the switching mosfet for the 'always on' 5 volt power rail buck regulator. ...

I replaced capacitors in the portable AC adapter too.  It was awful inside, totally coated with cap electrolyte and a bunch of soldermask eaten away.  But has a nice steady 7.5 volts after cleaning and replacing the capacitors. No buck regulators?  I was wondering about that, because of battery...

My next round of checking resulted in an interesting power on failure.  Start the system, it displays that checkerboard background for a moment, and then usually goes on to mouse cursor and happy mac.  This time it did pattern, followed by the screen sort of 'bleeding away' or 'fading away'...

The hard drive works and the Portable will boot from it.  I also thought the hard drive was the primary failure source until I noticed that the vast majority of the time right after power is applied, it boots up fine.  So generally it's happy and fine when you go from no power sources to...

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...

Found a battery cover for the mac portable on Thingiverse this morning: https://www.thingiverse.com/thing:4660666