[middleofsweden]

I finally found the schematics for the mini 910 MB today.

DELL Mini 910 - LA-4421P KIZ00 - REV 1.0.pdf - 4shared.com - document sharing - download

I have been lurking here for a while and I have followed all the discussions about where to tap in a USB device/hub. There have been some concerns about all the internal USB connections runs on +3V instead of +5V.

I checked the schematics and this is true for the WWAN port, WLAN port and the BT module. However, due to the scematics the webcam should run on +5V (page 22). Same supply line as the touchpad but with 5V already in the connector.
I haven't disassembled my mini 9 just yet so I wonder.. Have any one measured the voltage between pin 1 and 5 on the cam connector?

I also found that external USB port 1 & 2 runs on the same regulator (U2) and USB port 3 runs on a separate regulator (U7). I checked up these regulators (Richtek RT9711). They have overheat and overcurrent protection and fault signal ability in use (monitored) and they are good to supply 1,5A continuously. So a good (read protected and USB prepared) +5V source would be pin 6,7 or 8 on regulator U7 (3rd USB port). (Page 28)
If soldering to pin 7 on U7 it shouldn't matter if it accidentaly short circuits to pin 6 or 8. They are already shortened internally in the chip, and (due to the schematics) on the MB.

[AaronASB]

Originally Posted by middleofsweden

I finally found the schematics for the mini 910 MB today.

DELL Mini 910 - LA-4421P KIZ00 - REV 1.0.pdf - 4shared.com - document sharing - download

I have been lurking here for a while and I have followed all the discussions about where to tap in a USB device/hub. There have been some concerns about all the internal USB connections runs on +3V instead of +5V.

I checked the schematics and this is true for the WWAN port, WLAN port and the BT module. However, due to the scematics the webcam should run on +5V (page 22). Same supply line as the touchpad but with 5V already in the connector.
I haven't disassembled my mini 9 just yet so I wonder.. Have any one measured the voltage between pin 1 and 5 on the cam connector?

I also found that external USB port 1 & 2 runs on the same regulator (U2) and USB port 3 runs on a separate regulator (U7). I checked up these regulators (Richtek RT9711). They have overheat and overcurrent protection and fault signal ability in use (monitored) and they are good to supply 1,5A continuously. So a good (read protected and USB prepared) +5V source would be pin 6,7 or 8 on regulator U7 (3rd USB port). (Page 28)
If soldering to pin 7 on U7 it shouldn't matter if it accidentaly short circuits to pin 6 or 8. They are already shortened internally in the chip, and (due to the schematics) on the MB.

Some pics of the actual mobo with some added graphics such as arrows or something would be more helpful than the schematics, I know I have trouble reading them. I am not being facetious.

Thanks home slice.

[middleofsweden]

Originally Posted by AaronASB

Some pics of the actual mobo with some added graphics such as arrows or something would be more helpful than the schematics, I know I have trouble reading them. I am not being facetious.

Thanks home slice.

As soon as I rip it apart I will take photos and try to mark it as clear as possible. I will also measure the voltage on pin 6,7,8 on the regulators to confirm it. The same with the cam connector. Only reason I haven't ripped it apart yet is that I'm still waiting for my order containing fine soldering tips, tools and ESD gears (I'm always nervous to "zap" thingies under the cabinet).
Once it arrives I will get on with it :-)

[middleofsweden]

Originally Posted by middleofsweden

As soon as I rip it apart I will take photos and try to mark it as clear as possible. I will also measure the voltage on pin 6,7,8 on the regulators to confirm it. The same with the cam connector. Only reason I haven't ripped it apart yet is that I'm still waiting for my order containing fine soldering tips, tools and ESD gears (I'm always nervous to "zap" thingies under the cabinet).
Once it arrives I will get on with it :-)

Just ripped it apart.. and made the U7 mod, it worked like a charm. Still havent checked the Webcam though, mostly because the connector there is still on backorder so I decided to go for BT connector instead...

I personally will not use the BT module, but I needed a port to tap in to so my choice was to modify BT connector at MOBO to handle both 3V and 5V. Here is how I did it.

The frist pic is the MOBO cloesup of area just behind USB3 external connector.



Point one is the Regulator U7 legs #6-#8. They are inteconnected, both internally in the IC and on the MOBO. I aimed for leg #7 when I tapped in but if you aim for #8 it will not matter if you clutter solder tin on leg #7 or even #6. They are already shorted.

Point two is the filter cap (C72) for external USB port #3. It is soldered to the same rail as pin #6-#7 on the regulator. It is also a nice place to tap in, even if you don't own a fine tip soldering iron. (You can also go for the right side of C56 or the empty place where C77 would have been here but it is a more delicate work and requre a fine tip and steady hands)

Point three is the actual USB port. No explanation needed here... They are on the same rail.


The second pic is just an explanation of how I got here.. it is an exerpt from the schematics of the MOBO. You can see the connections of the whole PS of the USB ports (including the C72 solderpoint)


http://img835.imageshack.us/img835/4...latorsu1u7.jpg

All these points carry +5V from "inside" the regulator. It means current protected and monitored voltage. With other words, if you mess up when you tap in here you get a second chance to correct it (it will be obvious in the dev. manager). If you tap in to the main +5V rail directly and mess up the chance is far more greater that the mini 910 don't boot at all.. or just die..


The third pic explains how I tapped in to the BT port. Pin #2 is unused and would be a great neighbour to pin #1 with pin #1 carrying +3V and pin #2 carrying +5V.


http://img521.imageshack.us/img521/8379/2pinbt.jpg

The red ring shows the "blind" #2 connector on BT port. This is the one I soldered to pin #7 on U7 regulator.

So.. Now I have a panelmate connector that carries USB +/-, ground, +3V (pinout as Dell BT) and custom +5V protected and monitored for whatnot +5V devices I feel to connect in future without soldering anymore to the MOBO.

Maybe this post is a couple of years too late but hopefully itgives some ideas how to keep the 910 "flexible" after a mod.

[tismon]

Very nice work. So then, in your opinion, what would be the easiest place to get your 5v usb +/- from on the bottom of the motherboard?

[qh187]

Do you have another link to that schematic?