Hp 290 g4 (all usb ports don't work)

[zaurus81]

Hi all. All the USB ports on this desktop computer are not working. Computer starts normally but it has only usb ports, no ps2 for mouse or keyboard. The motherboard is labeled KENT REV:A M11. I searched online for a schematic but couldn't find it. I checked the USB port EMI filters to see if any were broken, but they are all ok (they all beep). I have 5 volts on a 5 pin SMD component labeled REDFC (see photo) that is near each USB port, but 5 volts are not present on the USB port pin. I don't know where to start. Need schematic

[FriedFred]

Hi, what is the power consumption at all for this board?
This 5-pin component can be a high-side switch or a linear power supply IC or just a transient voltage suppressor IC.

[SMDFlea]

RE*** SY6288D20AAC

[FriedFred]

If this number is true, then it's really a high-side switch, a power distrubuting IC.
I looks like, this IC is several times on this board? Each USB port has it's own IC?
According to this pinout:
1 - OUT (get switched-through the IN voltage)
2 - GND
3 - OCB (over-current signalling, usually open-drain, needs pull-up and is low-active)
4 - ENB (enables the IC)
5 - IN (Usually 5V input)

So if I'm correct, the "OCB" is not active, because it's "HIGH". Also, the "ENB" is active, so the chip shall work.

Do you have a short at the USB port 5V? At the connector? Or no short, but just no 5V?

[zaurus81]

If this number is true, then it's really a high-side switch, a power distrubuting IC.
I looks like, this IC is several times on this board? Each USB port has it's own IC?
According to this pinout:
1 - OUT (get switched-through the IN voltage)
2 - GND
3 - OCB (over-current signalling, usually open-drain, needs pull-up and is low-active)
4 - ENB (enables the IC)
5 - IN (Usually 5V input)

So if I'm correct, the "OCB" is not active, because it's "HIGH". Also, the "ENB" is active, so the chip shall work.

Do you have a short at the USB port 5V? At the connector? Or no short, but just no 5V?

Hi, thx for reply. I have no short on 5v rail, just no 5v on usb connectors of all motherboard (8 port). If i put a jumper wire from pin 5 to pin 1, i have 5v on connector and usb port works. Each one of this chip controls voltage of 2 usb ports.
Where did you read that ocb is active low?
If it's a SY6288D, the enable signal is a ENB, which is active low from datasheet (see photo)

[zaurus81]

RE*** SY6288D20AAC

hi, thx for reply. Can you explain me how you found it from the smd code?

[FriedFred]

"Where did you read that ocb is active low?"
This is a standard, because usually those signals are open-drain. So they can be connected with other ICs from other voltage rails. For example, 1.8V or so. Usually, this signal is used by the EC chip or CPU directly. But can also be connected with a bigger power supply IC (PMIC).
Which logic levels do the signals "ENB" and "OCB" have?