Why would my flash be firing when attaching to hotshoe, but then not afterwards?

Question

Odd one.

I've got 3 X Canon 580 EX IIs. They all seem to work fine on my camera hotshoe. When I attach each one to the hotshoe, it does not fire during the attachment process. It then all works as expected when pressign the shutter button.

However, I also have 3x Godox X1R-C wireless recivers and a X1T-C transmitter.

with 2 of the X1R-Cs, when I attach any of the flashes, the flash triggers without me touching the test of pilot button. This happens everytime without fail. Once attached, then everytime I press the 'TEST' button it will never fire the flash. It seems to fire maybe 2mm before being fully into position.

However on 1 of the X1R-Cs, this does not happen. When attaching it doesn't fire, and then the test button works as expected. Even more confusing is if I turn off each of the X1-R-Cs and remove the batteries, 2 of them fire the flash when attaching, but one does not.

The reason I'm asking is that those 2 X1-Rcs do not work in manual mode, only TTL and I expect it's related to this issue.

As a side not, attaching each flash to the X1T-C does not trigger the flashes on attach, and the test button works.

Answer 1

Why? Because something is shorting the center pin of your flash's hot foot to the ground contacts on the hot foot.

That something seems to be two of your three Godex X1R-C receivers.

External flashes do not draw any energy to power the flash from the hot shoe to which they are attached. The energy is either self-contained or provided by a separate power source independent of the camera's. Back when electrical flash units first came into wide usage, most cameras were strictly mechanical devices that had no electronics or power sources. Even the ones that had very small batteries to power built-in light meters couldn't possibly provide enough energy for even a single flash discharge. The flash contacts merely provided a connection to a switch that closed mechanically in sync with the shutter fully opening which allowed energy to flow from the flash, through the switch, and back to the flashtube.

It seems your X1R-C units are defective. I'd consider returning them if that is practical. It's also possible attaching/removing them with the flash powered up and charged could have damaged them. ALWAYS turn off a strobe before connecting/disconnecting it from the hot shoe on a camera or receiver. Ditto for any PC connections between a flash and camera/receiver.