My Mac Portable's battery wiring harness looks like somebody tried to put on a new connector but didn't have the right tools so they just haphazardly twisted wires together and taped them. I have 9V connectors and want to fix this the right way, but when looking at a picture of an apparently unmodified Portable battery harness I see a heatshrink wrapped bulge on the wire that runs to the positive terminal of the 9V backup battery. It looks like there's some heatshrink shown in one of the diagram's in Apple's service manual too. What's in here? Is it a diode to drop the voltage down or keep from blowing the regulator if someone tries to connect the 9V cell backwards? Maybe just an inline fuse?
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Question about Mac Portable battery wiring harness
- Thread starter DragonKid
- Start date
I have not pulled mine apart but the switch is what allows the 9 volt battery to hold the computer in sleep and not lose settings while changing battery. What people seem to do is find a 6 volt power supply and hack it to the harness to run bypassing the charging and work since the battery is required for operation.
Ah. I actually have a good battery, and just replaced all the caps in my Portable tonight. I'm just trying to figure out what that extra part between the + terminal of the 9V clip and the switch is before wiring in a new 9V clip. Somebody would have to cut open the heatshrink wrap to know for sure what's in there, unless it's a diode or a resistor, then a multimeter could tell us that.
Well, I disconnected the connector on mine, I measured 8.57v at the battery connector but only 8.55 at the internal connector. If I had to guess, it probably has a polyfuse to prevent the hard drive from running off of the 9v and Schottky diode to prevent the 9v being charged or reversed. Techknight probably has a better idea, you should send a PM to him.
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Thanks a lot for your responses. And I definitely wouldn't ask somebody to cut up a working portable, worst case scenario I'll just try to buy a replacement harness from someone. A polyfuse makes a lot of sense, as would a diode, although 0.02V seems like an awfully low voltage drop for one.
4 pin connector. 2 bottom pins are ground. Top left is Reference, Top right is B+
When battery cover is removed, Top left goes from 6V to 9V, and top right goes from 6V to 0v.
And when battery lid is back in place, 9V falls back to 6V, and 0v goes to 6V.
thats it.
When battery cover is removed, Top left goes from 6V to 9V, and top right goes from 6V to 0v.
And when battery lid is back in place, 9V falls back to 6V, and 0v goes to 6V.
thats it.
So there's nothing of interest inside the piece of black heatshrink tubing visible on the red wire running from the 9V clip to the switch here? Sorry I don't have a better photo, that was the only one I could find, and it's possible that it's been repaired and the heatshrink is just covering a splice, but I thought I saw something that looked like heatshrink on that wire in the Apple tech procedures for the Portable as well.
And here's a second picture with a similar bulge visible on the positive 9V lead.
And here's a second picture with a similar bulge visible on the positive 9V lead.
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Ah. According to https://68kmla.org/forums/index.php?/topic/16733-macintosh-portable-recappingrepair-progress-questions/ what's actually in there is two 1N5817 Schottky diodes.
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