Hi all
I have a Dell XPS 8700 computer that went dead while charging a new powerbank through the front USB port. I have removed the PSU and mobo from the case and disconnected all other equipment. The current status is as follows
1) This particular computer has PSU BIST (Built-In Self Test) on the rear side and when pressing the test-button, the green LED lights, indicating a Pass. It also makes the CPU fan spin for the duration of pressing it.
2) When I prress the power button nothing happens. I do measure 3.33V on the pin header on the mobo although no 3.3v is provided through the 24pin ATX(-like?) power connector. For now I assume it must come from some on-board voltage-divider.
3) A green LED on the mobo is lit and the resistor next to it measures 5v. That could very well be the standby power that enables the power button (and WOL etc).
4) The onboard buzzer makes a faint clicking noise at 2 or 3 Hz, which suggests some power-rail is failing (or current-limiter is kicking in), but then again: why should it be powered? At this stage, computer is not switched on, there is no other power than the 5v standby and that seems to be OK!
5) Playing with the green wire on the 24pin power connector (connecting to ground) has about the same effect as pressing the PSU test-button: the CPU fan starts spinning, but stops when grounding the green wire stops.
6) I checked the mobo for shorts on powerlines and caps and the PSU for bulged capacitors and other visible signs of failure, but nothing...
Here a some other considerations: Buying a new (original) PSU is not really an option, but I would hate to thrash this computer. There are not many alternative PSUs that fit the case and provide proper power (the mobo seems to be picky about the PSUs it accepts). And on top of that: I just want to fix it, although I have little resources: no schematics, no scope, very limited experience fixing PSUs.
So I was hoping someone reading this does have a lot of experience, And recognizes the symptoms. Or relate a computer going dead to charging a USB powerbank? (it can't be coincidence)
I have a Dell XPS 8700 computer that went dead while charging a new powerbank through the front USB port. I have removed the PSU and mobo from the case and disconnected all other equipment. The current status is as follows
1) This particular computer has PSU BIST (Built-In Self Test) on the rear side and when pressing the test-button, the green LED lights, indicating a Pass. It also makes the CPU fan spin for the duration of pressing it.
2) When I prress the power button nothing happens. I do measure 3.33V on the pin header on the mobo although no 3.3v is provided through the 24pin ATX(-like?) power connector. For now I assume it must come from some on-board voltage-divider.
3) A green LED on the mobo is lit and the resistor next to it measures 5v. That could very well be the standby power that enables the power button (and WOL etc).
4) The onboard buzzer makes a faint clicking noise at 2 or 3 Hz, which suggests some power-rail is failing (or current-limiter is kicking in), but then again: why should it be powered? At this stage, computer is not switched on, there is no other power than the 5v standby and that seems to be OK!
5) Playing with the green wire on the 24pin power connector (connecting to ground) has about the same effect as pressing the PSU test-button: the CPU fan starts spinning, but stops when grounding the green wire stops.
6) I checked the mobo for shorts on powerlines and caps and the PSU for bulged capacitors and other visible signs of failure, but nothing...
Here a some other considerations: Buying a new (original) PSU is not really an option, but I would hate to thrash this computer. There are not many alternative PSUs that fit the case and provide proper power (the mobo seems to be picky about the PSUs it accepts). And on top of that: I just want to fix it, although I have little resources: no schematics, no scope, very limited experience fixing PSUs.
So I was hoping someone reading this does have a lot of experience, And recognizes the symptoms. Or relate a computer going dead to charging a USB powerbank? (it can't be coincidence)
