PowerBook Power Supply Connector (520/520c/540/540c)

[croissantking]

I don't believe anyone has tried running 15V for the vmain. We're all using 16V for vmain to power the laptop. Some of us are using 15V for the vbatt pin for charging the battery.

I have three power supplies. One of them is dead on the Vmain side so I switched the wires over so that Vbatt now powers the laptop. It works, mostly, just as long as I don’t draw too much power. Turning up the brightness and for example maybe inserting a floppy disk at the same time causes it to power off.

 

[mmu_man]

Well I guess I'll design a PCB for that to add inside, since all the boards I find on aliexpress are too large. More fun. Already found a possible chip to use.

 

[jmacz]

Well I guess I'll design a PCB for that to add inside, since all the boards I find on aliexpress are too large. More fun. Already found a possible chip to use.

 

[mmu_man]

So, someone confirmed using 15V Vmain without trouble for a year, I guess we're pretty safe there.

I have three power supplies. One of them is dead on the Vmain side so I switched the wires over so that Vbatt now powers the laptop. It works, mostly, just as long as I don’t draw too much power. Turning up the brightness and for example maybe inserting a floppy disk at the same time causes it to power off.

That's not a voltage problem but a current issue: with full brightness you'll draw about an amp already idle, so using anything more will try to pull more amps, but since Vbatt is capped at 1A, the voltage will drop to compensate, and it doesn't like it. That's why Vmain can provide 1.5A.

 

[3lectr1cPPC]

I am also using 15V on VBATT without issue.

 

[mmu_man]

So, the only thing I hate more than people forcing me to published unfinished work because they are redoing what I spend nights already doing, is people wasting time doing what I already did…

GitHub - mmuman/cad-mac-pb500-pwrconn: DIY Power Connector and USB-C adapter for PowerBook 500 Series

DIY Power Connector and USB-C adapter for PowerBook 500 Series - mmuman/cad-mac-pb500-pwrconn

github.com

Oh, A voltmeter variant, because people love useless displays… (untested yet)

 

[mmu_man]

Needs some more margins but it works:

 

[mmu_man]

Updated the model to make it easier to assemble with the meter.

 

[mmu_man]

Just tested myself for the sake of it, it happily triggers overcurrent protection at 1.3A if I let it charge on a bench supply. So definitely needs some circuit to calm it down.

 

[mmu_man]

So, just confirmed on my PB520c, Vbatt is drawn almost directly to charge the battery (it drops at 11.7V), but it's disconnected when it thinks it's fully charged, so I only have to implement current limiting.