Apple powermac g3 blue.white Service Manual

 

 Troubleshooting

General/Logic Board LEDs - 9

 

DS5 = USB port 1- lower

DS4 = USB port 2- upper

When illuminated, these LEDs indicate that the computer is 

providing power (+5 V) to downstream USB ports. USB devices do 

not need to be connected in order for these LEDs to illuminate. 

However, if one or both of the LEDs is not illuminated and a USB 

device is/was attached (and the system has completed its boot 

process), then the logic board has removed downstream power 

because of a trouble condition.

Since the downstream power is controlled individually for each 

port, it is possible to have these LEDs in a different state: one off 

and one on. This way if one port has troubled USB devices, the 

other port can still be functional. These LEDs are not immediately 

illuminated at the beginning of a restart or cold power-on. During