Hello everyone,
I’m looking for help diagnosing a no-power issue on an ASUS ROG Zephyrus G14 (GA402R / GA402RK series). ❗ Problem


The laptop does not power on at all:

• No LEDs
• No fan spin
• No response to power button

The issue started right after a RAM upgrade. The previous owner mentioned there may have been static discharge during reassembly.

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🔍 What I have checked so far (with a multimeter)

• AC adapter is confirmed working
• 19–20V is present at the DC jack
• Both input MOSFETs have 19–20V on both sides
• Multiple inductors near the eDP connector

...

I am troubleshooting an AVT150 amplifier. The standby pin is at 0 V, so the amp remains muted.

I have the schematics attached.

Key observation:

• The standby pin is 0 V (muted condition).
• If I remove T104, the standby voltage is restored.
• With T104 removed, I have 4.7v on standby pin and TDA can see signal generated.

This suggests T104 (or its surrounding circuitry) is pulling the standby line low, but I am not yet certain whether this is due to a faulty transistor, a control signal upstream, or a protection condition being asserted.

Has anyone...

This is my first attempt at troubleshooting a board like this, I know I could just buy a new board but I'm curious to figure out how this works. I've been testing different components in the evenings this week and I think the problem is with the IC failing to start up for some reason. When the board is plugged in there is no standby voltage.

Then today it randomly sprung to life like a zombie but shortly died thereafter. I have no idea why it would have done that and its the first time I've seen it running. I discharged capacitors on the board last night, then it was sitting today....

Hi. I got a Vizio with no power or standby, and won't turn on with remote or button. I checked the voltages on the connector and all read 0.00V or nearly 0(0.050 ON/OFF pin). None of the pins are labeled STB for standby although I do see some 5V pins. Other than the obvious standby led, which isn't coming on, is there a way to check for standby voltage on this PS. I'm trying to see if my problem is the PS or mainboard. Some Vizios I have fixed with no standby led me to think it was the PS but it turned out being the mainboard. Any experience with this set would be greatly appreciated.

Hi all.

I started a thread while back regarding TV power supply standby circuitry as it is something I am not quite on top of.
SMPS theory and function is becoming more familiar, however the standby part is still a bit of a mystery.

Anyway, a friend has this TV with the above mentioned power supply board which has no standby voltage, nor any other voltages leaving the board.
The mains AC comes in fine, gets filtered and rectified with power is on the main filter cap as well as the transformer and drain pins of the ICE3B0665J, but that's it.
...