Originally Posted by sentrme

Solution #1: I unplugged the USB plug from the AC adapter and lightly scratched the pins with a knife or tweasers. I found out that in order for the Transformer Prime (TFP) to display the charging icon on the screen, the TFP has to recieve 12+ volts from the wall adapter to initiate (Fast Charge = 12v - 15v). Any time that the wall adapter was used to charge and the Charging icon does not appear most likely your TFP is only getting 5v (Slow Charge), same as connecting TFP to PC with USB cable ( Only if your PC recognizes the TFP when plugged in ).

For solution #1, can you explain more precisely what did you do with wall adapter to gain an output from 5v to at least 12v? Are you also in Europe like me? Maybe in USA wall adapter gives 15v of output power? Can be this reached in Europe with a special wall adapter or something else?

On USB connection I know that depending of motherboard, usb fastcharging can be enabled. In my case, I can't do it.

Thanks! Regards!

Originally Posted by Vidda77

For solution #1, can you explain more precisely what did you do with wall adapter to gain an output from 5v to at least 12v? Are you also in Europe like me? Maybe in USA wall adapter gives 15v of output power? Can be this reached in Europe with a special wall adapter or something else?

On USB connection I know that depending of motherboard, usb fastcharging can be enabled. In my case, I can't do it.

Thanks! Regards!

I can't speak for sentrme, but the voltage is dependent on the adapter itself having adequate power from the wall (it should be the same whether you're in Europe or the US since the US uses 110 volt and Europe uses 220volt, but it may vary from socket to socket depending on how well they were installed and wired). I've noticed a few sockets in my (fairly old) apartment cannot seem to provide adequate current, but others can.

Originally Posted by superhyper

I can't speak for sentrme, but the voltage is dependent on the adapter itself having adequate power from the wall (it should be the same whether you're in Europe or the US since the US uses 110 volt and Europe uses 220volt, but it may vary from socket to socket depending on how well they were installed and wired). I've noticed a few sockets in my (fairly old) apartment cannot seem to provide adequate current, but others can.

Thanks for the reply

I don't know why, but in any wall socket I get the same result. Don't worry, this is more a curious doubt than a real problem. After all, my prime charges, although maybe not in the fastest way.

Regards!

I ordered a new usb wish me luck guys :/

Sent from my PG86100 using XDA

Superhyper took the words out of my mouth. I livein the US but my apartments wiring is crappy. But I ran into the charging problem again. Im not sure what is causing it this time. Im pulling out my multimeter to test the output voltageof the wall adapter then wall adapter + USB powercable. Ill post my findings in a little bit.

Vidda77 let me know if you get different results with new AC adapter? Did you order the wall adapter and usb cable?

---------- Post added at 07:21 PM ---------- Previous post was at 06:46 PM ----------

I just found this forum post that explains more about the charging scheme at transformerforums. I cant post the link so i copied the text into the next post.

I think my ac adpter isnt recieving a signal from my TFP over the middle 5th pin. I dont know if i can clean the 5th pin pbut im going to try.

Im getting really irritated with this proprietary AC adapter and modified USB cable. ASUS should of made a full AC adapter for charging then included a separate Usb cable orjust enabled file transfers over the normal USB 2.0 port.

Does anyone know if the power charging signal that is sent to the AC adapter handled by the kernel or firmware?

---------- Post added at 07:26 PM ---------- Previous post was at 07:21 PM ----------

Posted at transformerforums by Frederuco

"First, to search for 3 character term, put it in quotes. For instance, search for USB Charging, use "USB "charging

Secondly, why did ASUS choose 12-15 volts to charge? Well, the batteries output 7.5 VDC to run the system. Using 5 VDC (standard USB) means the charging circuit has to bump up the voltage.

Also, the higher the voltage, generally the more efficient the charging circuit and the resistance of the circuit becomes less of a draw. This is why power companies do not send out 120 VAC from the power plant, but a much higher voltage and step it down close to your house at a substation, and then again at your house to 240 VAC..

With that being said, charging the tablet on 5VDC @ 2 amps would take quite some time especially if you have the dock and tablet. I know my tablet alone charges faster than my wife's iPad 2 and my tablet alone last a bit longer than hers does without a charge.

That 5th pin you are asking about allows the ASUS wall wart charger to detect the Eee Pad devices. If you plug in a phone to it, the wall wart will put out 5 VDC @ 2.0 Amps instead of the 15 VDC that the Eee Pads use.

Another thing, my wife's iPad will charge via a computer USB port, but it is slow. She is forced to use the apple wall wart just the same as I have to use the ASUS wall wart.

I should mention that the Eee pad series will charge via USB, but it is slow and does not show that it is charging. It will only charge if the screen is off and the rate is abut 3% per hour. Using an iPad charger the rate increases to about 10% per hour with the screen off."

Thamks Frederuco