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Macintosh PowerBook 1400cs/166 Power Supply Replacement

Posted by: TheMightyMadman on 2024-12-18 14:27:12

Hi all,

I've got a Macintosh PowerBook 1400cs/166 in for repair for a friend of mine, as it wasn't starting up.
I've replaced all of the SMD electrolytic capacitors on the mainboard, control switch board, and LCD board.
However, all that happens now when using the original PSU is that the speaker clicks and the screen backlight flashes.

I've tried testing the PSU output when it's disconnected from the laptop and I'm not getting 24Vdc, only up to about 200mV and it seems to change when I move the cable around - is there a bad connection in the PSU cable, or is the PSU not supposed to output 24Vdc when not under load? Is it a smart charger?

The PSU is a Macintosh PowerBook 45W AC Adapter model M4896, output 24Vdc@1.87A. Can anyone recommend a suitable replacement if it is bad?

The cells inside the onboard battery pack have also started to leak, so the battery pack is duff. I've pulled it apart and gutted the batteries. I tried out some cheap emergency lighting cell packs as they were 2.4V 4Ah and seemed to be 4/3AA cells pre-welded two in series so would be easy to assemble, but they were slightly too long to fit in the pack unfortunately. I'm tempted to try out a pre-built pack like the one below, if the dimensions are correct - these should have a built-in thermistor and thermal fuse, too:

Battery for Fukuda FCP-7101 MB333BHR-4/3AU 9.6V Ni-MH 4000mAh / 38.40W

www.fusionbattery.co.uk

Many thanks,

Adam

Posted by: MacUp72 on 2024-12-19 09:50:14

when the charger is bad you can try to open it and look for bad caps..I havent dont that before for a 1400/3400 because mine were/are all still working. On ebay UK there are some modern replacements..

Posted by: 3lectr1cPPC on 2024-12-23 16:47:58

If the voltage varies when you fiddle with the cable, then it's probably a break in the cable rather than bad caps. Not that these supplies never need recapping, my first 5300 supply (same PSU design, different connector) needs it.

Posted by: TheMightyMadman on 2025-03-29 09:59:41

Thanks everyone 🙂