Seller Note “this item does not switch on.”


  • Resistances
    • VCore – 0.9Ω (OK)
    • Vmem – 22.2Ω Samsung K4G80325FC-HC25
    • Display rail – 21.7Ω (OK)
    • VDCI – 27.8Ω (OK)
    • 5V – 5KΩ+ (OK)
    • 1.8v – 3.4KΩ (OK)
    • 12v – 6KΩ+ (OK)
    • 3.3v – 2.5KΩ (OK)
  • Voltages
    • 12v – present
    • 3.3c -present
    • 5v – present
    • 1.8v – present
    • Display Rail – 0.91V
    • VDCI – 0.97V
    • VCore & Vmem are missing


  • I should investigate the Vmem controller.
  • I probed fuse F5 (12V) and there was a spark, possibly it is faulty?

Investigating the display rail

Buck converter GS9238

This component is generating an expected voltage of 0.91V

Investigating the VDCI rail


Investigating the Vmem rail

The PWM is UP1666Q

The required voltages appear to be present

Pin / NameVoltage
PVCC5V (correct)
EV1.75V (Hopefully this is enough? should be 1.8V?)

Let’s take a look at the MOSFETS it drives

1 x HGATE AON 6414A

Gate Resistance – MΩ+

2 x LGATE AON 6354

Gate Resistance 1 – MΩ+

Gate Resistance 2 – MΩ+

I am not seeing any PWM signal on the gates. Maybe that enable signal isn’t high enough? Or possibly the PWM controller is faulty? Since EN on the Vmem PWM is only 1.76V (possibly too low) and my current understanding is that POK on the Display Rail PWM provides this voltage (reads 2.07V), then perhaps there is a resistor that has changed value?