Thursday, March 31, 2011

Enable Download Mode on Galaxy S with USB jig

Just a quick post. I stumbled on a 'how to make a usb jig' that would allow any Samsung Galaxy S to boot into download mode, meaning any Galaxy S that couldn't perform '3 button recovery' can now boot into download mode (like mine)!

So all you need is a 301k resistor (I made mine from a 300k and a 1k), 1% tolerance, connected to pins 4 and 5 of the micro usb plug. There are plenty of youtube videos showing how to join and position the resistor/resistors without soldering and even without using a micro usb plug, but I wanted to more permanent jig so I soldered and heat-shrink'ed it.

Here's the pin layout for the micro UBS on the Galaxy S. I stripped mine from a $2 (delivered) cable from ebay.

So pin 5 (red) is Power, 2 (white) and 3 (green) are USB data, 4 is not used normally, and 5 is ground (usually black but mine was blue).

My trial run, which happily worked.

Cleaned it up a little (excuse my soldering, not my finest work).

A little heat-shrink...

...and after a few layers more and its done. Just turn the phone completely off, plug the dongle in, wait a few seconds and its booted to download mode.
I've had perfect success with 301k and 1% tolerance. There are varied reviews saying 300 or even 270 will do it but I'm not sure about the specifics. 301 has been 100% successful for me so I'm happy to endorse that :)

So after booting to download mode I flashed the leaked 2.3.3 European rom, which ended up flashing my boot so I now have 3 button recovery. That made me pretty happy but I've kept using the USB jig anyway just because its so simple.

All up it cost about $2.90AU (including the cable) and 3 minutes of my time. These jigs go for $25+ on ebay.