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Ok guys, i'm the recent proud owner of an EEE motherboard which has taken some abuse from its previous owner. Suffice it to say that the AC input does not work. (see: http://forum.eeeuser.com/viewtopic.php?id=19570)
So here is my idea; make or buy a regulated power supply and connect it to the battery terminal of the eee. I have noted 9 inputs on the battery connector, 2 large and 7 small so i'm guessing a simple ~7.5v to one pin and gnd to another is going to cut it.
My questions:
is this feasible? if so what are the pins on the battery connector for? which one will I have to supply a voltage to and how much voltage? I assume some are for the battery maintenance/capacity level indicators.
Finally, what regulator should I get or what voltage should I aim to put accross the connector? I tried measuring the voltage of one of my batteries but couldn't get a reading.
Thanks guys.
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Any ideas?
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Someone is gonna have to crack open an existing battery to trace back the pins or the flipside trace the motherboard. What you'll probably find is a common ground in conjunction with a bunch of positive leads...
I'm going to assume that the positive leads are individual cell taps so that the charging circuitry (again assuming) in the motherboard knows the balance state of the cells in the pack.
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Your best bet is to try to fix the ext DC input and apply power there.
Did you get any further with the analysis of the last fix attempt? The blown component wouldn't be a fuse, cos fuses don't "burn" when they fail... they just fail (blow open); that's their reason for being. So I would guess that it was either a resistor or a capacitor that toasted on the mobo. Which means there might be a blown
semiconductor somewhere that caused the burnup, but didn't itself "burn" . Comparison with an untoasted mobo should reveal what component toasted up.
Have fun...
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Are the two longer connectors for the batteries for ground? That's what i always assumed they were.
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Probe around with a multimeter and find out.
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The long ones have always been ground on things I have messed with but I haven't specifically looked at the eee.
Buzz it out on the motherboard.
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kenn wrote:
Your best bet is to try to fix the ext DC input and apply power there.
Did you get any further with the analysis of the last fix attempt? The blown component wouldn't be a fuse, cos fuses don't "burn" when they fail... they just fail (blow open); that's their reason for being. So I would guess that it was either a resistor or a capacitor that toasted on the mobo. Which means there might be a blown
semiconductor somewhere that caused the burnup, but didn't itself "burn" . Comparison with an untoasted mobo should reveal what component toasted up.
Have fun...
Fuses do fail short that is why full fuse rating includes breaking capacity as well as blowing capacity. If they blow with a current flowing that is greater than the breaking capacity then they will fail short circuit.
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Fixing DC input is looking unlikely...
I dont get a reading from the battery on those 2 large prongs... perhaps it needs jump starting with a voltage on one of the other connectors?
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What about wiring the (or a replacement) dc connector direct to the famous ground and 5v rail?
I cant see why battery would owrk but mains doesnt.
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Jel, are you proposing I wire up the 9.5v jack to a 5v USB port? Even if the voltage was correct there'll be diodes e.t.c. which would stop reverse charging.
Also, the DC input has some pretty complex circuitry to charge the battery, supply power to the board e.t.c. it isn't just a matter of the battery and DC input going to the same place.
The charging circuit is done for so i need to find a way to run the board with some sort of supply replacing the battery - i just need to know what each prong is for and the voltage required on each. I could wire the DC jack to the battery (internally) manually to charge it but its gonna be pretty dodgy.
Last edited by no1knows (2008-04-02 9:54:25 am)
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Hadn't thought about mains power AND battery charging so no point going down the avenue I had in mind (which was dubious in any case!)
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Let my try to explain my view.
You could get a lithium battery charger (plenty available to RC bateries) and connect its terminals to first and last battery cell on the wees pack. That way it would charge the pack the same way the main connector/eee charger circuit charges it.
I'm pretty sure this could work. If you try it, tell us the result.
Last edited by macsoft (2008-04-09 3:19:25 pm)
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My findings after poking around with a volt meter and a external 7.5v power supply...
When connected up and powered up, the two large prongs are the +ve and gnd (the outer prong is gnd). It measured 7.8v.
Just removing the battery, and connecting an external 7.5v to the prongs do not work. It seems that the prong at the other end needs to be connected to gnd as well. With this prong also connected to gnd, the eee will now start up. Unfortunately, the eee will shutdown in a few seconds. I guess that the eee hardware checks the smart inputs from the (missing)battery, and concludes that it is critically low, forcing a shutdown.
****Possibly dodgy advice follows****
My suggestion is to connect a 7.5v external power supply to the two large prongs(via a diode for proper isolation), with the battery still connected, so that the smarts still work. Don't exceed 8v, or you may charge the lithium battery improperly(i.e. bad things will happen). I haven't tried this, so ***do this at your own risk***
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My suggestion is to connect a 7.5v external power supply to the two large prongs(via a diode for proper isolation), with the battery still connected
Nutin personal, but this is a bad, bad idea. You're basically bypassing all of the over volt / over current protection built into the charging circuitry that is there to keep your battery from going pop fizzle.
Using the common ground you identified already, poke and prod the remaining pins. I suspect you'll find varying output voltages from +/-4v up to the full pack voltage. These would be the individual cell balancing taps.
If it follows standard conventions each will be a positive lead that by itself would output a little under 4V. The trick will be constructing a harness that replicates that behavior.
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Thanks for providing the partial pin layout of the battery plug that I am looking for. This reminds me about the psu of desktop pc. When the soft power button is pressed, it short one of the pin in the psu-to-mb socket to ground, signaling the psu to start up and enter working mode. I wonder if there is similar mechanism in notebook (i.e. eee) battery? If they are similar, then, following your observation, if you leave the "other prong" to ground after the eee starts, it will behave the same as one continues to press and hold the soft power button in a desktop, which the mb will consider as a shutdown signal. What do you think?
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Success!!!
Finally managed to boot up the eee from the battery prongs (and stay booted). Here are the pinouts of the battery that I've figured out so far.
UuuuuuuuuuU <---- looking at the connector on the battery. The big U's are the bigger unconnected guide slots
from left to right:
. gnd
. ?
. 14K thermistor (?) - other end is gnd
. 8K thermistor - other end is gnd
. Switch (connect this to gnd to turn on the battery)
. ?
. ?
. +ve
. gnd
To power up the eee from an external 7.5v source:
1. connect the two gnd prongs together, and connect to the 7.5v external gnd
2. connect the 7.5v external +ve to the +ve prong
3. place a 18K(only one I had handy) resistor across the 14K thermistor prong and gnd
Boot up!
Note: the 14K thermistor might very well not be a thermistor. The resistance didn't seem to drop that much upon cooling.
Last edited by kangkeng (2008-04-14 1:35:28 pm)
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Exelent news! So if I want to do my battery switch (Macsoft Switch 
http://forum.eeeuser.com/viewtopic.php?id=24126 ) all I have to do to prevent the eee from access the battery is to put the switch on prong you call "switch"!
Thanks!
Last edited by macsoft (2008-04-14 1:59:15 pm)
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kangkeng,
In your step 3, should the 18K be connected to the gnd, or just touch the gnd? Also, for the "switch", any +ve supply if the switch hasn't connected to the gnd?
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thats good work kangken..
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Is it possibile that that 18K thermistor is really a shunt to detect battery level?
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Kithera wrote:
Is it possibile that that 18K thermistor is really a shunt to detect battery level?
Doesn't seem to be. The battery level seems to be directly related to the voltage level on the +ve input. Seem to recall that when powered at a little over 7v using the above setup, my Windows battery gauge gave a 10% reading. At over 7.5v it gave a 60% reading.
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senderj wrote:
kangkeng,
In your step 3, should the 18K be connected to the gnd, or just touch the gnd? Also, for the "switch", any +ve supply if the switch hasn't connected to the gnd?
The 18K was continuously connected to gnd.
The +ve supply is cut off when the switch is not grounded.
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no1knows wrote:
thats good work kangken..
Thanks.
So... how goes the repair on your eee?
Last edited by kangkeng (2008-04-23 10:50:36 am)
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abandoned i'm afraid, someone will get a bargain on the parts
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