Dead Box?

[felix11]

I have a box that does nothing when u press the power button. It was working, then I switched off and attached its HDD and it failed to power up. So I removed the HDD and it still won't power up.
Anyone know what the problem might be? and how to fix it?

[cgscott]

Power pushed right in at the back? Maybe you have shorted the supply. Check the light on the brick. Hold the power button in for a few seconds and see what happens. Has the catch on the from power button maybe got caught and you think you are pushing it in far enough?

Did you remove the HD with power on?

[felix11]

Thanks for the response CGS. The power lead is fuilly in at the back, and its not the lead itself as that works fine on another box.
I have tried holding the power button in-no effect. I have also tried stripping it down and pushing the power button with a piece of dowel to make sure it is actually operating-again no effect.
I didn't remove the HDD with the power on, but I do suspect the HDD is faulty as the first time I switched on with the HDD connected in went 3 red rings. So I powered off, re-seated the HDD and powered on again. This time it started OK but I noticed it was not recognising the HDD - so I suspect this is faulty. Since I powered down and removed the [faulty] HDD it will not power up again.

[cgscott]

Strange to say the least. Check for any resistors blown near the HDD Connection. Also if you have another power button module handy. Replace the one on the console and see if that makes any difference. DO you have a multimeter?

If so use it to check there is power going in at the back of the console. Never heard of this happening before.

All i can think of just now.

[felix11]

Thanks again CGS- Tried with a different power brick-still same. As for multimeters,yes I have one but I havn't the faintest how to use it! Better someone with appropriate knowledge test capacitors etc!

[m1lad]

Dead Box -Felix11

The below is courtsey of G0t M4xx 21 from a site I once stumbled on.

Bear in mind you will need some electronics knowledge otherwise you could do youself harm.


If the PSU is confirmed working, it is either something wrong with the microcontroller in the southbridge that controls the power on sequence, the linear regulator that powers it and/or the ROL board, or a short in the 5V standby (blown capacitor, transistor, etc).

The easy way to determine which one of these is the problem is to look at the light on the PSU, if when you plug it into the 360 it turns red briefly (or stays red), there is a short on the standby power (If the short was on the switched supply, the 360 would power up then flash 3 red lights with error 0001 or 0002, or power up for a split second then shut itself off). Also measuring the resistance from 5VSB to ground is a pretty sure fire way to tell

If the 5V standby power is NOT shorted, then the issue is either in the power button on the RF board (easily tested by powering up the box via another method), the southbridge, the the voltage regulator supplying it.

The two regualtors are U5B1 (3.3V) and U5B2 (1.8V). They are located on the top of the motherboard near the back, jsut to the left of the large screw hole in the center of the motherboard (near the fans). The large tab opposite the 2 smaller pins is the output of each regulator, so they should measure 3.3v and 1.8v respectively when the 360 is in standby (off but plugged in).

If those measure ok, then I'd say the southbridge is dead (that motherboard is nothing but a nice paperweight).

Regards,
m1lad

[cantongodfather]

can u pm me please Felix