A: The internal charger IC on the RM-908 is limited to 450-550 mA. Using a 2A charger will not damage the phone; the phone will only draw what it needs.
Whether you are a mobile repair technician, a hobbyist, or an owner of this rugged device, this guide provides all the pinout schematics and practical advice you need.
FBUS requires specialized hardware and software. Standard USB cables will not work.
| | Signal | Description | | :--- | :--- | :--- | | Pin 7 | FBUS RX | Serial Data Input (9600 – 230 400 bps) < 0.8V = ‘0’, > 2.0V = ‘1’ | | Pin 8 | FBUS TX | Serial Data Output (9600 – 230 400 bps) < 0.8V = ‘0’ @ max 4 mA, > 1.7V = ‘1’ @ max 4 mA | | Pin 9 | SGND | Signal Ground (charging ground) | Nokia 105 Rm 908 Usb Pinout
The Nokia 105 RM-908 relies on a MediaTek (MTK) chipset. When connecting via USB, the device often requires a placed between the BSI (Battery Status Indicator) pin and the GND pin to force the phone into "Boot Mode" or "Meta Mode." Without this, your computer may register the connection as an unrecognized device. Required Tools for the Modification
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To flash the phone or fix software issues, you must solder a modified USB cable directly to these test points or use a specialized flashing clip (Fbus jig). Why Do You Need the USB Pinout? A: The internal charger IC on the RM-908
On the RM-908 motherboard, look for a small square pad labeled (Test) or "POINT6" near the SIM holder.
For "dead" phones or auto-restart issues, a specialized flash interface or "F-bus" cable is connected to these points to reload the operating system. General Device Codes
If Windows displays a "USB Device Not Recognized" error, check your solder joints. Ensure the RX and TX lines are not flipped, and verify that the MTK VCOM drivers are correctly installed in your Device Manager. FBUS requires specialized hardware and software
(Note: On the RM-908 PCB, these are usually gold-colored contact pads labeled accordingly or arranged in a vertical row. Locate the GND point first to orient the others.)
If you never need data, ignore D+/D- and TP703/TP704. A simple two-wire charger (only +5V and GND) will work perfectly.
The RM-908 features typically used for these operations:
Apply a tiny amount of flux and solder to both the motherboard pads and the stripped tips of your USB wire.