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My Macintosh Portable adventure

Hello all,

The last few weeks i've been studying the various repair threads of the forum in order to get my own portable running. I'd like to thank everyone here on this forum for providing such a treasure trove of knowledge. Thanks to all that, i now have a working portable.

So this is more of a show and tell and thanks post then a help wanted one. I found this post my mc128k: power regulation to be very usefull in diagnosing what was wrong. Also Techknights replies to various posts were a great help.

I got the Mac Portable M5120 with a backlit display, ram board and modem from ebay early januari. It was a non starter to begin with, although it still tried to do something when power was applied to the barrel plug. It turned out that the fuse on the mainboard was dead. One of it's previous owners had done a full recap of the system but i think it wasn't cleaned at all and maybe even the old solder was left in place because some of the caps weren't attached to the board at all or by very dull looking solder points. I cleaned a recapped it again.

The mosfet that drives the harddisks 12V was looking a bit green and there was a whole load of cap goo underneath it, on of the traces that controls the gate of the fet was also gone.

The final point was a short and a bad trace on the Hybrid board. The LT1054's "cap+" and "cap-" pins had less then 50 ohms between them, and one of the traces from the chip to the cap on the mainboard measured about 20 ohms. I removed the corrosion between the 2 traces and added 2 wires to repair the connections.

and after this, the portable booted from floppy and from the harddisk. Even the backlit display works.

So, thanks to everybody on this forum for sharing your knowledge.

one of the things i do need some help with is getting software from windows onto the mac. Most disk images i find are for 8ook drives and nothing seems to be able to write those. The only other apple computer i have is an Apple 2c. Is the SD card floppy emulator a good way to do that? I guess the the floppy emulator would be usefull for the 2c aswell.

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LaPorta

Well-known member
They are fun little machines. Half the battle on most is just cap replacement and finding a compatible battery. I find that that works for most people, except if there is leaky cap damage.

 
They are fun little machines. Half the battle on most is just cap replacement and finding a compatible battery. I find that that works for most people, except if there is leaky cap damage.
i'm not really an Apple or Mac user at all, i mostly have MS DOS portables, and a few other systems like an Osborne 1 and a Commodore SX-64. The fact that Apple made a luggable Mac was the reason i had to have a working one in the collection.

If the previous recapper of this one had paid a little more attention to what he or she was doing it would have worked great. The fact that all the cap goo was left on the board was a large part of the work I had to do now.

i have another portable, i bought it 2 or 3 years ago. i recapped that and cleaned it but it has never done anything. When i hook that board up to the bench power supply the draws 0.018A and that's all, even at the battery terminals.

 
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