Will replacing the capacitors fix this...

[chipped]

hi all,

I bought a external 2.5" inch HDD case the other day and it has 2 plugs on it, 1 is a USB plug which provides power and data, the other is a DC in just incase the HDD cant be powered by the USB alone.

Now when I plug the USB by itself into a front USB port on any computer it just wont power up, you can hear the drive drive trying to turn on rapidly and the LED flashes on and off. If I plug the USB by itself into any back port (mobo port) of any computer it works fine.

So i was thinking if i replace the standard capacitors with some bad boy big ass ones will it increase my chances of starting up from the front USB using the USB cable alone. It almost powers up using the front USB with just the USB cable, just a tinge more and it will start up I reckon.

Thanks

[kc8adu]

Re: Will replacing the capacitors fix this...

drive exceeding the 500ma limit?
if the box is stable and no blown caps seen its likely tripping the ocp on that port.

[chipped]

Re: Will replacing the capacitors fix this...

i tried 2 different Hard drives in the same case. My mates USB hard drive works fine on my case though, one plug on the front port.

[zandrax]

Re: Will replacing the capacitors fix this...

Welcome chipped.

That's not a capacitor issue, but a limit on current a peripherical can draw from USB: 500 mA at 5V, a max power of 2,5 W. Most notebooks and mainboards respect this limit, but some desktop motherboards may allow draws up to 1 A. Front ports are "weaker" form this point: they usually respect the limit.



Some drives aren't power hungry and can be powered through a single usb cable: they are usually 2.5" 4200 rpm disks (saw some old Toshibas).
Others require more power, so they are shipped with a Y-shaped USB cable (one end for data and power, the other for power only) or are battery powered (rare). 3.5" disks have always an external psu because they draw much more and require both 5 and 12 V, while 2.5" use only 5 V.

Zandrax

[gdement]

Re: Will replacing the capacitors fix this...

Powering external drives from the USB port makes me nervous about damaging the port, especially with laptops. I'd definitely use one of those Y-adapters, whether you seem to need it or not.