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How does iBook power input board work?

poiihy

poiihy

macrumors 68020
Original poster
Aug 22, 2014
2,303
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I've got an iBook power supply and a power input board (aka "DC-in" board). When I plug in the PSU and connect the output plug to the power board, some glitchy things happen with the indicator light...
It's rather random so it's hard to explain, but basically, when I touch the metal fabric sheathing on the output wire bundle (the wires that connect the power board to the logic board) the light glows amber, though dimly (it flashes very frequently, like PWM dimmed), and when I touch the shroud of the plug or any metal pieces nearby that are connected to that shroud, the light glows green, though dimly (PWM). And if I touch both, I think the green overrides the amber, but I'm not sure... I don't quite remember, but I know for sure one overrides the other, not make both lights glow at the same time.
But there are variations to this. I think the green only glows when I am grounded, so when I am not grounded, it won't glow, but the amber will still glow even though I am not grounded. Though this is often not the case and sometimes it does other random things...

Well anyway, how does the board work? How does the board tell the plug what light to use? How can I control the light manually?
 
Uhm…my understanding is that orange means charging while green means power/charged.

There is no other meaning.

As to why your iBook lights up like a Christmas tree when fiddling with the plug, I honestly can't say.
 
Yes I know that amber is charing and green is full, duh

No no no this is a BARE iBook power board and ONLY a power board (aka "DC-in" board). Not a whole ibook!
 
There's nothing to charge so it can't turn the Amber charging, but when you are grounded, it represents to iBook chassis which serves as a ground. That being said, since there isn't a battery to charge the light will be green like it would be on a computer with no battery
 
But for some reason when I touch the metal cloth sheathing thing on the bundle of wires, it makes the amber light glow. Even though that metal sheathing doesn't seem to be connected to anything...
 
Does it do the same thing with a different power brick hooked to it?

I have a spare power brick that will power my powerbook, but won't charge the battery for some reason.
 
poiihy said:
But for some reason when I touch the metal cloth sheathing thing on the bundle of wires, it makes the amber light glow. Even though that metal sheathing doesn't seem to be connected to anything...
Click to expand...
Ah, but the metal, which you could call the shield IS in fact connected - to YOU! Well, it's not really a good connection, as you would mostly have enough "conductivity" to modify grounding, and likely why the power LED would change color. It's probably nothing that you can predict.
The light on the power adapter plug will be controlled by the DC-in board itself, in conjunction with the power circuitry on the logic board, and finally, by the charge status of the battery.
 
DeltaMac said:
Ah, but the metal, which you could call the shield IS in fact connected - to YOU! Well, it's not really a good connection, as you would mostly have enough "conductivity" to modify grounding, and likely why the power LED would change color. It's probably nothing that you can predict.
The light on the power adapter plug will be controlled by the DC-in board itself, in conjunction with the power circuitry on the logic board, and finally, by the charge status of the battery.
Click to expand...

But the metal fabric sleeve on the cable is not connected to the board so I don't know how it would cause the board to change the light to amber when I touch it.

Do you know how the board works? The circuitry? How can I modify the board to control the light manually? How does the board control the light?
 
poiihy said:
But the metal fabric sleeve on the cable is not connected to the board so I don't know how it would cause the board to change the light to amber when I touch it.

Do you know how the board works? The circuitry? How can I modify the board to control the light manually? How does the board control the light?
Click to expand...
I suppose if the DC-in board is just plugged in, but not installed completely, that the ground (the shield that you touch) is modified by your own body resistance, and therefore changes the state of the LED. Not too great a mystery there.
I can't tell you exactly which circuit components are the controlling elements, but I do know that the power is controlled by the 3 parts (DC-in board, logic board, and battery. And, ultimately, the control for the LED comes from both the DC-in board, and the power adapter. The correct operation would be the result of having the DC-in board properly installed (including the internal plug and the screw that both holds the board in place, and provides other ground path for the chassis shield. Any other mode of operation (such as plugging everything in without actually installing the board) will be unpredictable, at best.

And, don't forget that the iBook power LED has 3 states (not 2) - green, orange/amber, and red (which is an error condition - some folks don't distinguish between the orange and the red states, but they are different colors, eh?)

Why do you need to control the power connector LED manually? Are you just trying to do that for fun - or do you have some goal in mind?
 
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