I have an old powerbook 100 that when I turn on it gives me an empty blue screen and no chime at all. The motherboard and the LCD have been fully recaped. I'm using a 6V 3A power adapter. Please let me know if you have some tips!
Powerbook 100 with blue screen and no chime
- Thread starter MacManiac
- Start date
Two things to try:
1. Use the proper AC adapter. The 100 is supposed to use a 7.5V 2A supply. Anything else may not let it start, and risks damaging the logic board. Apple was pretty explicit about this in their documentation, so it is more important than it is for the average computer.
2. Check if any of the three inductors near the bottom right of the board have gone open circuit.
1. Use the proper AC adapter. The 100 is supposed to use a 7.5V 2A supply. Anything else may not let it start, and risks damaging the logic board. Apple was pretty explicit about this in their documentation, so it is more important than it is for the average computer.
2. Check if any of the three inductors near the bottom right of the board have gone open circuit.
Oh - and also - do you have to press a key for it to start (normal behavior), or does it power on as soon as power is connected?
Before the recap it started as soon as I plugged it in but now it turns on when I press a key like it should
The 3 inductors are working. I've been using this 6V 3A adapter on a powerbook 145b and it works on there. Is there some sort of security on the powerbook 100 preventing other power adapters?
I believe the issue is more that the PowerBook could (will?) draw more current than its designed to support if you don't use the proper (limited to 2A) power supply.
There is no way that if you give more current to the device it will use more then it's rated. Imagine a gardening hose, the hose is the 3A. The powerbook is a container connected to the hose and it can hold up to 2A, if you fill the containar with more water then it could hold, it will overflow and you can't fill it any more. And this is the case with the powerbook, it can't draw more power then it's designed to.
Except imagine the container is a pressurized chamber instead of an open one, so instead it explodes when you try to overflow it. In any case - what you said is true most of the time, but the PB100 is a re-engineered Macintosh Portable, which had horrific power management design, so it can get problematic. On the Portable, you will absolutely blow out half the chips on the logic board if you use a supply rated over 1.5A with no battery installed. The Portable's power manager only regulates voltages on the battery side of things - so without a battery, it won't regulate properly, and eventually the happy little chips on the logic board will get sent a high enough voltage to blow them out. The 1.5A supply the Portable shipped with isn't enough to power it on its own, only to charge the battery, so this works fine. If you use a 2 or 3A supply on a Portable, that is enough and bad things happen.
The PowerBook 100 uses the same power manager design as the Portable, only they fixed the issue that made the Portables blow up with more amps. That being said - the Portable power manager is very finicky in other ways, and it wouldn't surprise me whatsoever if 6V wasn't enough for them, or that 3A was still not healthy for them. Apple did explicitely say that the 3A charger would damage the PowerBook 100 and also the 150's logic boards if used on them. My guess would be that like the Portable, it will charge the battery at a higher current with the 3A supply, which I'm sure isn't good for the battery.
All that is to say - get yourself a 7.5V 2A supply. They're like $10 on amazon or eBay. I'd recommend an aftermarket one as the originals all need recapping.
I generally agree, but the PB 100 is apparently not a fixed current (A) draw device. The way I normally think about it the voltage of a power supply is what maters, the amperage is just a max that the PS can safely supply. No harm no foul to use a PS with a higher Amp rating as long it is above the max current needs of the device. The device will only draw the current it needs no matter what the PS might be able to supply.
However something about the PB100 design means that it can pull more Amps than its actually designed to support and therefore is reliant on the PS only being able to provide a max of ~2 Amps. I highly suspect this is related to the charging circuity and perhaps only applies if you have a battery installed but that's a guess on my part. (If I'm right that would mean you could use a 3A PS as long as you didn't have a batter installed but again I'm just guessing). I could see Apple not wanting to split hairs on if you could use a higher rated 3A PS in some situations and just saying not too in general but again that's just a guess. What we do know is they definitely documented that you should only use a 15W or 17W (2A or 2.27A) PS with the PB100:
I'm basing some of my thoughts here on the PowerBook 500 series PS. It actually provides two independent 2A 16V feeds to the laptop (Vmain and Vbatt), my understanding is when folks looked into this you could not tie them together and feed it with a modern 4A 16V PS as the battery would draw to much current/overheat. Of note VMain works fine with a 4A PS.
Thanks I will try to find an official one and recap it. Sadly I live in a very small country where ebay and amazon are not available