T42p + USB HD + USB PSP Charger = Burnt T42p

[rsramirez]

Hey folks.

So I was working on my T42p this morning. I was copying files from my USB HD, and figured I'd charge my Playstation Portable (PSP) before my flight later today. Since I hate carrying around alot of power adapters, I have a USB-to-PSP charger that I've been using for a number of months now. As soon as I plugged in the PSP, the computer immediately turned off. I then smelled the dreading "burning smell" coming from the vent of my beloved T42p.

I unplugged the power adapter, and then turned on the computer. After booting, my ActiveSync popped-up an error message about no connection (I sync via BT). Then the computer died again. I plugged in the power adapter, and it has been running since. BUT, when I opened the BT control panel, there were no devices. I clicked on add, and received an error message that there is no bluetooth device on the machine. I tried Fn-F5 and tried to reset the BT - no good.

Thanks to this board and a simple search, I immediately found the part I need and ordered it on ebay.

So just wanted to pass on this warning:
T42p + USB HD + USB PSP Charger = Burnt T42p

-Roy

EDIT: It gets worst. USB doesn't work. I'll have to try my old PCMCIA-USB adapter at home. This sucks.

[bill bolton]

figured I'd charge my...

USB ports do have a finite limit on the amount of energy they will deliver (a maximum 5.25V at 500 mA, for 2.625W of energy). Attempting to recharge another device's power storage through a USB port seems to be a fairly common ingredient in USB failure reports.

A USB connected device is supposed to be able to respond to an interrogation from the USB host controller about their power demand. However, simple "charger" connection do not do this, so the controller has no idea of what power they actually need. The USB spec is based on devices connecting in a low-power mode (~100 mA maximum) to allow interrogation on their power demand before switching, with the host controller's knowledge to a higher level of power demand. A dumb power charger connection can't do this.

Our consulting workgroup made the decision that since we do a lot of field work on client sites, we'd put up with the minor hassle of carrying extra chargers rather than risking ending up without USB on our T4xs, and we simply dont attempt to use USB ports for recharging phones, PDAs etc etc!.

Since we made that decision about 9 months ago, we haven't had any USB failures across a population of 80 or so T4x systems of varying ages.... and we do use a wide variety of USB devices. Prior to that we had a number of seemingly random USB port failures.

While its not a controlled study, its certainly "strongly indicative" of a causal relationship between using USB ports as a power source for power charging purposes and USB port failure.

Cheers,

Bill