900c, dim red charge LED

Finally got to put my MP900c back together today. Got it all together, slapped in a battery, plugged it in, and the charge LED blinked green, then switched to a really dim reddish-orange color. Unit wouldn't power up. Unplugged AC, removed main and backup batteries, pressed reset switch. Put both batteries back in, same behaviour. Unit will power on for about 10 seconds on just main battery, give me a low battery warning, and shut down (battery has been sitting for about a year). Tried leaving the AC plugged in for about 10 minutes, still dim red-orange color (got nervous that I would fry something if I left it plugged in any longer). Unit runs fine on just AC, after pulling both batteries and pressing reset switch. Same behaviour whether backup battery is installed or not, also same with new backup battery. If I'm running it on just AC (no batteries installed), and I shut it off with the power button, I have to unplug it, then plug it back in before it will power back up.

I loaded CMONEX 1.0 on it some time ago, although I'm not sure when. Build date is Apr 13 2007. PIC Firmware 4.19.7. Bootloader 4.10.

Is this just a matter of batteries sitting for over a year just dieing, or is something else going on?

EDIT: Just checked the three batteries packs with a multimeter, and using the outer most pin on the left and right, I get the following:

Pack 1: 7.4VDC
Pack 2: 8.1VDC
Pack 3: 8.4VDC

So I don't think old, dead battery pack is the problem

EDIT 2: I was able to get it to power up on just battery with one of these packs, it goes through the initial screen calibration procedure, and on to the desktop. If I press the power button to turn it off, it won't turn on, and I get no response from any of the LEDs if I plug the power supply in. I have to remove both batteries again to get any life back out of it. Is it possible that I have some level of firmware corruption going on, and I just need to reflash it? I've been kinda fearful of just trying it, as I'd like to avoid bricking it altogether, lol.

Edited by urbex 2009-01-08 8:32 PM

Update: I forgot about this for a while, and pulled it out last night to play with it again. Unfortunetly, I didn't pull the backup battery when I put it up last time, so I couldn't check off that i tried leaving it without batteries overnight, lol.

Anyways, I found that if I power it on AC ONLY, then plug a battery pack in, it does appear to charge the pack properly. Shows charging in the power section of the control panel, and shows a bright orange charge LED on the front of the unit. But same behavior as before - either clicking suspend off the control panel, or pressing the power button causes the unit to shut down as expected, but the charge LED goes off, and it's impossible to power the unit back up until the battery and AC are removed then replaced. When it gets powered up at this point, it goes through the screen calibration, as if it's been hard reset. The backup battery appears to be good, both with a voltage measurement, and according to the control panel power applet.

I finally decided that the unit is near useless to me in it's current state, so I wouldn't lose much if I did end up bricking it by reflashing it. At first I tried loading just CE.NET 4.2 on it, replacing the CMONEX rom. I used the compact flash method for that, and it appeared to complete properly, but didn't fix the power/charge issues. I then tried reflashing the 4.10 bootloader along with the CE.NET 4.2, and again it appears to go ok, but didn't change the power/charge issues.

At this point, I'm stumped. It seems to be a software issue, as everything runs OK when I get the thing to power up, including what appears to be proper charging behavior. But as soon as I try to suspend it or power it off, the whole thing goes dead.

I wouldn't rule out a problem with the battery pack. You might try picking up a spare 900 battery pack and seeing if the same thing happens. Do you know if the original battery pack has ever been rebuilt?

The two OEM NEC packs show no evidence of ever being cracked open, and one of them is labeled as a laptopsforless.com pack. No idea if it's a "new" pack, or a rebuilt/relabeled OEM pack, though it does show signs of having been cracked open.

But even assuming all three of these packs were completely screwed up, shouldn't the unit function properly running on JUST AC, with the battery pack removed?

What are you using for an a/c adapter....original Mobilepro 900 series charger or something else? Low amperage a/c adapters will appear to charge the battery, but don't really supply enough current to charge the battery and operate the unit simultaneously. Charging a battery with one of these adapters will condition the battery to not take a full charge, requiring the battery to be reconditioned. Normally charging the unit with a 2000mAh rated a/c adapter will do the trick, restoring full funtionality to the battery.

Only two possible things really....bad mothrboard in the unit, or bad batteries (assuming the a/c adapter meets original specs and is functional)...

Only way to check it out: swap them out with someone elses unit...

I have both a NEC OEM charger, as well as a custom 12VDC, 2200mah adapter I built several years ago when I first got the MP. Both adapters produce the same result. Both are producing 12VDC as they should while operating the unit (checked on the motherboard connections while running with a multimeter). Haven't checked current draw yet though.

From everything you've described it sounds like something has gone awry with the motherboard. One last thing...check the contacts real good on the battery connector where the main battery plugs into the unit. Make sure they are making good contact.

it totally doesn't seem to be a software issue to me as you have reinstalled the entire firmware including bootloader. if you hadn't, you'd have a chance it's just a corrupt bootloader (I had that with simpad sl4 once). btw if you soft reset instead of power off/suspend, does that work?