USB -C Hub HDMI Failure

 VAVA 7-in-1 USB C hub VA-UC017,  3x USB 3.0 5Gbps USB A ports, SD/uSD card slots, HDMI, PD charging port 100W max.  $25, 100x40x13mm, 60g (31g w/o casing). It worked well with both PC and Android phone for about 3 years before the HDMI stopped working; other functions still seem to work.

We will try a teardown and see if we can identify the problem.  

Opening up was a little difficult.  The casing is one piece aluminum with both ends plastic; one end is the USB C cable and the other end is the HDMI connector.  The plastic is secured to the casing with epoxy; we had to pry open the USB C side. 

The PCB appears to have a date code of 2021-01-11 and the assembly time is maybe 21-03, consistent with time purchase time of 21-05.    The USB C cable wires are hand soldered to the PCB and the soldering work is rather poor, but the connections appear intact.  The USB C wires seem OK: the USB 3 signal pairs are individually shielded and power wires are large gauge.  Overall, the component assembly seems good; I did notice a few solder balls, but overall the PCB is clean.  Also note the conductive foam on top of the HDMI connector and SD/uSD card slots.  The aluminum casing is anodized; the areas contacting the conductive foam are exposed.

VL815-Q7 by VIA Labs is a USB 3.1 Gen1 4-port hub controller. VIA's VL102-Q4 is a DisplayPort Alternate mode and Power Delivery 3.0 controller for USB-C devices.   DP Alt Mode allows the transmission of DisplayPort signals over USB-C connector.   ITE Tech IT6563FN is a 4-lane DisplayPort 1.2 to HDMI 2.0 converter.  MA8121N is a USB 2.0 SD/MMC card reader controller, by Prolific Technology or possibly a Chinese clone.  Puya P25Q40H is a 4Mb SPI serial Flash.  SM4307 is a P-channel power MOSFET by Sinopower.   There are three switching regulator ICs, maybe one or more LDOs,  Two of switching regulators are likely M3Tek's MT3121NSBR, 5V Input 1.5A/2A(Peak) 2.5MHz Synchronous Step-Down Converter. There are a number of SOT-23 components, which are either transistors or LDOs.

The HDMI connector does not appear to be well soldered; there is no solder above the holes.  Also interesting a number of components on the HDMI signals are not populated; they could be ESD protection devices, or filters, like TI's ESD224, or STMicro's ECMF4-2450A60N10 (ESD and common-mode filter),  which the footprints seem to match.  

I reflowed all the HDMI connector pins, but the HDMI still does not work.  It'll require a more in-depth troubleshooting, which we try in the future.