So QHYCCD sent me the info on the mod they'd made to make the USB 3.0 interface start up with the camera rather than being out of sync with the camera due to running off the USB power supply. The mod is a single jumper between two 0402 components, so it's definitely not for the faint of heart. You need a good SMT rework station with microscope and pinpoint soldering iron. The USB circuitry on the QHY247C gets its power from the USB port, while the rest of the camera operates off the 12V supply. However, if the USB is connected first, the camera interface doesn't start up correctly. QHYCCD came up with a solution that requires a jumper on the PCB, presumably to hold the USB chip in reset until the 12V supply is powered up. Rather than sending the camera back for modification, they asked me to make the modification myself. Luckily I have the microscope and SMT soldering iron needed to accomplish the task. I still need to test everything completely, but this folder shows the disassembly and re-assembly of the camera.
Four screws hold the back plate on the camera. It's interesting to note that the holes in the cover are beveled for flat or oval head countersunk screws. A ground wire attaches from the USB board to the back panel with a screw that also holds a wire from the power jack. The power jack plugs into the board opposite the USB board. The body housing is just a sleeve that slips off over the heatsink and PCBs. The power supply and USB boards each have coarsely 3D printed parts that attach them to long standoffs using shorter standoffs for the end cover. The boards just sit in a slot in the bottom 3D part but are screwed to the top one.
With the two short standoffs removed, the USB board is held by two connector-less ribbon cables. I HATE dealing with these flexible printed circuit connectors. The one visible on this side with the white cable uses a connector style that's not too bad, but the back one is a pain to reconnect. Neither gives me total confidence they're seated fully when re-installing.
On this top side of the board you can see the large Altera FPGA. To the left is the Cypress Semiconductor USB 3.0 chip, and above is an apparently obsolete Micron Gigabit SDRAM. To the right of the FPGA is a flip style printed ribbon connector. This also has another view of the 3D printed mount.
On the back are all the connectors (mostly for programming the board or other applications) and various passives under a conformal coating. The other ribbon connector is visible as the black bar above the white housing in the upper left.
The USB startup fix consists of adding a jumper between a resistor near the ribbon cable connector and a capacitor at the edge of the board. I'm assuming the capacitor is on the chip power supply coming from the 12V input and the resisotr is going to the reset pin of the USB chip. That would hold the USB chip in reset until the power supply comes up. Normally a mod like this would also include cutting a trace to break the original connection, but hopefully this will work!
These are 0402 parts so they had to be done under a microscope with my finest SMT tipped soldering iron and even then it was a challenge. I also had to carefully remove the conformal coating around the area.
The solder joint at the resistor doesn't look very pretty, with some residual solder on the isulation and conformal coating. That connection was a real challenge getting the solder to melt at the board/component interface. That part must have a via to the ground plane very close to the connection. I didn't want to apply heat for two long as it would potentially loosen the whole component or damage a trace on the board.
Re-assembly is pretty much the reverse process. Getting the cables reconnected was tricky enough.
Even re-connecting the ground wire was a bit of a challenge dealing with the tiny screw and washer that kept wanting to go anywhere but where I needed them.
As usual there are more photos in the gallery. Enjoy!