Macintosh Portable

[bd1308]

I've been on this quest to resurrect a Portable from motherboard death. A well-known portable collector gave me a box of motherboards from the non-backlit and the backlit series. I'm going through each of them and making lists to buy caps for these guys to fix them. Also documenting the PDS slot and RAM slot to see what I can come up with. Also found a way to get a CF card to work on the SCSI bus

Stay tuned.

 

[ClassicHasClass]

Good luck. I'm tempted to drag my Portable out to play, but alas I'm out of town this weekend. I'll do it when I get back.

 

[Anonymous Freak]

You're going to make all of us "dead portable" owners jealous!

 

[Trash80toHP_Mini]

I've got the Docs on both slots in GttMFH:Second Edition. You might find it online somewhere, if not, I can copy the pages to pic-n-post for you.

The ROM Slot is actually one of the more promising avenues for exploration! }

 

[H3NRY]

Yes, dead portables are becoming common in the last 2 or 3 years. The 5120s are suffering from leaky caps, mostly, and are fairly easy to fix if the corrosion hasn't spread too far. The backlit 5126es have tantalum caps for the most part which don't leak, but the voltage regulator custom IC is failing in many of these. If you work out a fix, we'd love to know. One day when the world smiles and I have spare time, I hope to figure it out. Probably replace a lot of the existing power circuit with newer, reliable parts.

 

[Anonymous Freak]

Oooh. Power regulator sounds exactly like what could be wrong with mine!

 

[ClassicHasClass]

Mine might be bad cappy. I'll investigate. Right now it just clicks, but won't boot.

 

[ClassicHasClass]

Actually, I take that back. It looks like a power problem. After the two-fingered power manager reset, I can get a pointer to appear, but as soon as it tries to spin up the hard disk the system dies. The Pb battery is definitely dead. What power supply are you guys using with yours?

 

[H3NRY]

If you want to boot one without a good battery, you need a later PowerBook AC adapter, one that puts out at least 2 amps. I use a model M5652, which is 3.0 Amps at 7.5 Volts. It's still not as reliable as having a good battery. The surge of power needed to spin up the HD is too much for the original AC adapter. However, once booted, a non-backlit portable draws a miserly 6 Watts. Not bad for a Mac twice as fast as an SE.

 

[4seasonphoto]

What's the story with the custom voltage regulators, and can an off-the-shelf part be substituted?

 

[H3NRY]

Don't know. I started tracing out the power supply of the beast, but haven't got it figured out yet. It's pretty complex with stuff feeding back on itself. If anyone knows of a schematic it would save weeks of reverse engineering. This is an early design before switching boost-buck regulators were available from IC vendors, and it's all Apple. It appears to use capacitor ladder boost circuits instead of inductors as we do today. The hybrid controller in the 5120 probably will offer some clues.

I'm almost at the point of unsoldering everything in Apple's supply and building from scratch. Integrating with the custom power management processor is going to be interesting. In all, this is a long-term project. Ask me again in a couple of years.

 

[ClassicHasClass]

H3NRY, I'm using a 7.5V supply at 2A. Would that be sufficient, or should I go for a 3A one instead?

 

[4seasonphoto]

I guess it was too much to hope that the voltage regulator could be replaced with an off-the-shelf 3-pin 5V or 12V regulator...

My 5125 will probably need another battery rebuild but seems to otherwise be working fine. I think I should hook it up to a small solar trickle-charger so I can keep the circuits energized for free.

 

[LCGuy]

I just want to say, I think that Portable looks mint! :O

 

[4seasonphoto]

Thanks! I lucked out a few years ago and got it for $25 from Mac Shack in Boulder and did a full restoration on it except for the space bar, which I will probably RetroBrite at some point.

 

[Trash80toHP_Mini]

Very cool, 4SP! I need to fire mine up just to see if it still works. :?:

Any o'youse gots just the Case, an extra DOA Luggable, or a Numeric Keypad to downsize your collection?

} )

 

[4seasonphoto]

Seconded on the carry case, and I wouldn't mind having a set of manuals either.

 

[H3NRY]

'm using a 7.5V supply at 2A. Would that be sufficient, or should I go for a 3A one instead?

2A is what Apple lists as the power draw for the 5120. If it boots, it's sufficient. If not, I guess you need 3A. 2A is borderline for booting these old girls with old lubricant in the disk drives. Remember these AC adapters are no spring chickens either. They are 20 years old, and I had one go bad. Unfortunately it went from 7.5V to 19V out, and fried my Power CD player. Fortunately it wasn't a Portable.

 

[ClassicHasClass]

No, this is a third-party power adaptor. Unfortunately 2A is the maximum output, so when I'm at Fry's next I'll get a 3A.

And mine has the case, and none of y'all can have it. The case really is spiffy.