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[traxtar944]

Well I was modding my xbox today and was doing integrated controllers with relays. I plugged in the xbox and it won't turn on.

When off, I get readings of 4.7v on all orange wires, and a reading of .4 volt on the powOK blue wire and yellow wire.

If I short the powON white wire againt an orange wire or the blue or yellow wire, it will turn on and operate normally...but the volume will be very quiet. When running, I get all normal voltage readings of 5v on the oranges, 5v on red, 12v on yellow, and 3.3 on blue.

Does this mean the 2T transistor by the Xyclops is blown?  I don't see any burn marks or anything. I'm just not sure if I'm experiencing the symptoms of a blown transistor or a messed up power supply. Thanks in advance for the help!

PS) I checked the voltage on the transistor when the unit was plugged in but off and got 0v....when shorted to turn on I get 2.2v

This post has been edited by traxtar944: Apr 3 2007, 03:49 AM

[traxtar944]

doesn't anyone know what could be causing these symptoms? How do I know if it's the transistor or the psu besided trying it on another xbox? Should the blue wire on the mobo connection be a 3.3v regardless of weather it's plugged into the xbox?

[FrostyTheSnowman]

You will need to replace the transistor. You can either order the exact same one that is on the board, or you can replace it with a compatible one from RadioShack.

Here's my thread on the replacement transistor from RadioShack:

http://forums.xbox-scene.com/index.php?showtopic=593432

This post has been edited by FrostyTheSnowman: Apr 4 2007, 03:36 AM

[traxtar944]

MMBT3906/LT1 - Trans SS GP PNP 40V SOT23 transistor (25 peices)

I got that transistor on Ebay. Is it the right one? How can you be sure it is the transistor?

Also...could shorting out the white powON wire with the blue powOK wire affect the sound volume?

[FrostyTheSnowman]

Yes that is the correct transistor. And as far as the volume goes, i'm not sure if it would affect it, but it is possible.

And I am sure it is the transistor because the XBOX powers on while jumpered, and does not power on otherwise. (This is a very common problem with v1.6 XBOXes.)  (IMG:style_emoticons/default/happy.gif)

This post has been edited by FrostyTheSnowman: Apr 4 2007, 07:22 PM

[traxtar944]

Thanks! Wow I was so worried I messed up all my hard work... Now I'll just have to try not to ruin the board while soldering and desoldering the transistors. Is a heat gun really ideal for this job?? I have a 15W and 30W soldering iron I can use.

This post has been edited by traxtar944: Apr 5 2007, 01:06 AM

[traxtar944]

Okay, well I replaced the transistor and now the voltages are 3.3 on standby and the blue powOK wire gets 3.3 volts on standby...so that worked. The only problem is that my xbox still doesn't power on unless the blue and white wire are jumpered! Any ideas on what else it can be? I'm thinking pin 14 and 20 on the xyclops chip...but I don't see any bad traces on the board.

On a positive note, the audio is back to normal volume....so the transistor DOES affect system volume. Interesting!

[FrostyTheSnowman]

Does it power with the eject button?

[traxtar944]

Nope, just if I jumper the powOK and powON wires. As soon as I take off the jumper wire, the xbox will shut off.

If I jumper the wires the fan will run  even if the system is off. As soon as I hit the power button the system will power on like normal and power off like normal, but the fan will not stop unless I remove the jumper wire.