• Hello MLAers! We've re-enabled auto-approval for accounts. If you are still waiting on account approval, please check this thread for more information.

PB 3400 Power Issues

I'm sure this isn't totally new, but I'll describe the chain of events specific to this PB.

I bought it on eBay untested.  There wasn't that much corrosion on the board.  I removed what I could, leaving (visible) three or four points of corrosion on the joints of a few resistors and maybe a small capacitor or two.

I replaced the power board out of fear some of the capcitors on it had gone bad nowithstanding some corrosion on the battery plug.  When I plug in the adapter, there is a whining sound - that mostly comes from the replacement power board.  The old one is less terrifying.  There's a 'pop' (not in a bad way) like when a Powerbook normally turns on.  That's it.  When I pull the plug, the same pop occurs again as if one were powering off a Powerbook.

There's no screen activity.  I think the speakers may be broken so I can't listen for a chime or anything else.  There's no VGA port - or ADB port - activity, but it's also possible (for the sake of argument) that both ports are broken.

Initially, when I tried to press the on key on the keyboard, or the sound/brightness up/down on the speaker part (that can be removed) I'd get a looping electronic sound on the speakers (a bad sound).  I then noticed that occurred when I pressed any key on the keyboard, so I replaced the keyboard with my 5300c's and that issue stopped.  Can I, for instance, plug the 5300c screen into the 3400c?  That'd be on the assumption that the VGA/ADB ports and the 3400c screen are all dead.

I realize that's an extreme longshot.  The only way it would be a valid hypothesis is if nothing I have so far done would have turned the computer on [because the fan hasn't yet gone on...].  I'm guessing power's not actually getting across the board - or not properly.  The real problem in trying to do this systematically is that I can't in any way vouch for the a) logic board, b ) power board, c) adapter, d) any other components...

 
Last edited by a moderator:
The whining of the power board I talked about on the other recent 3400 thread.

The caps are bad. Replace the 2 caps and that should disappear.

The pop and non screen come on has to do with something corroded in the area of the battery as one of my three does what you describe. One board I have makes the screen come on. So I was able to test the screens and 2 were fine. The issue is power output and signal to the screen. I cannot do board level repair and cannot justify paying for it so I am stuck.

The one that boots and shows the cursor shows the rest of the screen garbled and will not boot.

The one the screen does not come on will boot and go to desktop as you can make it do alert sounds. Neither of those 2 will allow output to external video.

 
I'd be really appreciative if you could send me a link to the topic. Until I'm sure a power board is working correctly, I'm not sure how much else I can do/diagnose.

 
And let me also ask this: my 5300c had a dead PRAM battery. It usually starts fine.

Initially, I thought I had noticed that it would not start at all without the dead battery connected. I removed the dead, corrosive PRAM battery from the 3400c and have a new one. The new one may be uncharged. I also replaced its two prong connector with the original 3 prong (red wire on the left). So on another long shot, the whining isn't the power board trying to charge the battery and the laptop isn't not starting because of the PRAM battery... or I didn't put the wires in correctly also?

I can't find the posts you're referring to, Macdrone.

 
Last edited by a moderator:
OK well that is interesting. Would still really appreciate your post...

I was wrong: my 5300c powers on without PRAM battery with the new power boats... which may not speak to what would happen with a working but otherwise defective board...

Idk. General help again solicited.

 
Last edited by a moderator:
I took some voltage measurements, though not very systematically.  On the logic board, I measured between ~1 and 3.5 volts (and nothing in places).  On the power board, I got a range of like 0.1 to 3.5 ish to just under 20.  Some of those seem like they must be wrong, but I don't know what to look for in Powerbooks.  The low board voltage is one thing but is there something/somewhere I can look to definitively test the power board?

 
Last edited by a moderator:
Is this a power board problem? Because if so I'd probably like to try and get my money back on the replacement board.

 
Last edited by a moderator:
Back
Top