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Well, I finally got to installing my Belkin BT dongle internally. I originally wanted it switched, but decided it was better to have it done than not done, and I didn't have a P-Channel FET on hand. While installing, I discovered some things that has convinced me it's possible:
1) Pin 6 is likely not working because a required pullup resistor was left out. A 10K resistor (Follow the traces, right over the BT in BT_CON) will pull up the line to 3.3v
2) I had NO mention of Bluetooth in the BIOS before this mod. Switching via F2 ONLY switched WiFi
3) After installing the BT Dongle, there WAS a Bluetooth option in the BIOS. Apparently the presence of a USB device on that specific port enabled it.
4) When using FN+F2, I now have a choice of both BT and Wifi, Just WiFi, Jist BT, and both off.
So, I'm going to order a P-Channel FET to use Pin 6 to switch the power to my Bluetooth dongle. If anyone wants to try it, I think it's very likely it will work, but no guarantees.
Also, the measured current draw of the Belkin bluetooth adapter I used (Don't remember the model number, but it's the smallest Belkin one I think) was only between 12 and 20 mA. This might shorten battery life by a whopping 2 or 3 seconds, so switching it off is really for reasons other than power savings.
Last edited by RChadwick (2009-10-29 1:17:59 am)
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What model 900 is this done on?
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Just a plain 900 (Not A), Celeron 900, Originally came with 4GB Flash and Linux, but upgraded to 16GB and Windows 7.
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Or you can just use "Softswitch" to turn Bluetooth on and off. . .
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I suppose Softswitch would work to make it look like it's not there, but it's still drawing power. I'm not bothered by that, as the BT current drain is tiny, but someone might want to put in a different adapter, maybe a larger/older Bluetooth adapter, a second WiFi adapter, GPS (Mine draws a LOT, despite the specs), etc. Also, hardware switching is the most reliable and universal among other OS's.
I didn't have a digikey order together yet, so I got some P channel MOSFETS on Ebay. Will mod my mod with on/off ability when they come in. It's a bit too simple to draw a schematic, but I'll take another picture with a description if anyone is interested.
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Well, normally the Bluetooth normally installed on these Eee PC's will have all the pins needed and it's just a trick of soldering them, since even experienced modders have found it difficult, if your Eee PC doesn't have the connector already soldered.
But your mod will be useful for other USB devices as you have noted, as most just use dip switches but your method may be more practical for single devices and setting up for software control switching.
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I'll share a secret. Flux is your friend. Flux makes the solder want to stick where it's at, and not make bridges. With enough flux, and the right amount of solder, an impossibly small soldering job becomes almost easy.
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Nice find man!
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Flux helps, solder wouldn't be very manageable otherwise, but it can't replace sharp eyes and a steady hand. . . not to mention a variable temp soldering iron with custom tips.
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RChadwick, I commend you on your soldering skills.
I decided to use a solderless hub inside and connect it to the webcam port as the 900A Woot special didn't have a webcam. Whats been noticed on the 900A's is that the line for the BT has been left out while all of the traces are there on the motherboard similar to your Celeron Asus 900. The mention of a pull up resistor is the first time I've seen this though. My initial assumption was to be able to use a ASUS BT module soldering all of the wiring to the traces on the board and it would be plug n play.
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does the 900hd have bluetooth? I looked around and didn't see anything.
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No, neither the 900HA or 900HD have bluetooth nor the soldering points for one. So you'll be limited to USB dongle type, or soldering one to a free USB point.
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zeo, noticed that the 900HD BIOS does mention BT though versus the 900A bios. See my other post in the "hacking/mod" section.
- petec
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Perhaps Asus modified the BIOS from another Eee PC model for the 900HD? Or the feature was added during one of the updates?
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It doesn't help us much, but if you're Asus, and you're making 1 million (Just a guess) Eee's, removing parts you don't need, even a few resistors and capacitors, might save $10,000 or more. An engineer who costs his boss $10,000 needlessly isn't getting a bonus check. From memory, there's the two resistors (?) on the USB data lines that are missing, the possible pullup resistor (I measured 3.3V on the other side of the pad, so it would make a lot of sense it's a pullup), and what I'd guess are two capacitors across the 3.3V supply. And of course the connector. Leaving out the connector alone might save Asus $250,000.
As for soldering, a good temp-controlled iron is very important. A small tip helps sometimes, but I prefer a slightly bigger tip, as it transfers heat better. I've found that, with a lot of flux, your soldering 'aim' doesn't need to be that good. I use much more flux than some might use, bathing the solder joint almost completely, and just clean it up later with alcohol. Flux is critical for large pin count surface mount chips. With a bath of flux, I can solder a 100+ Pin IC (With pin spacing so small I can't see it clearly) in a few minutes, with the result looking exactly like it was done by machine. I just run a blob of molten solder across the pins, and the flux makes the solder stick where it's supposed to be.
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Reading your posts is making me think of maybe soldering the ASUS BT module I purchased. I bought it with the connector for the non existing connector on my 900A. I could either solder a new connector on the traces (which I would prefer) or just cutting the wires and soldering them on directly. I would still be able to remove the BT module on the opposite side of the cable if I needed to replace it. I believe that maybe the Asus BT module would still work in MS even if not recognized in BIOS. I would still have to solder a couple of surface mount resistors (I call them insects) and two capacitors. I wonder if there is an Asus 900 MB picture of said area posted anywhere's out there.
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If you can get the connector, I think it would be much easier to solder. With the connector holding the pins in the proper position, you can solder them all at once, after tacking down the two big solder blobs on the ends. Doing it with wires means you have to carefully do each one. It's not impossible, but a lot harder.
I do remember seeing a 900 Motherboard Picture on here somewhere. Just don't remember where (Lost bookmarks temporatily in a Windows 7 Upgrade)
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zeo wrote:
No, neither the 900HA or 900HD have bluetooth nor the soldering points for one. So you'll be limited to USB dongle type, or soldering one to a free USB point.
lame 
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