[sparkston]

I recently acquired one of the original TR power packs. Although the device is basically the same as the current TR III power pack, producing 330v DC from 6 C cells, it has a three pin plug which is not compatible with the 2 pin socket on the AF-540FGZ flash.

It may be of interest to the forum to hear that I have successfully modified the TR Power pack to function with the AF-540FGZ as described hereafter:

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warning- this process is potentially dangerous and could damage your equipment- do not attempt unless you have suitable facilities and training. The following suggestions may be inaccurate or incomplete- you are responsible for understanding what you are doing sufficiently to spot such issues!
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The three pins on the power pack socket are arranged in a line, in a plastic block which is rounded on one end. The pin at the round end is +330v, the pin at the square end is 0v, and I don't know what the middle pin is for- if anyone knows, I'd like to hear it. Inside the cable, the 330v line is red, the 0v line is black and the middle pin has a white wire.

Meanwhile, the AF-540FGZ two pin socket has a short pin (on the left) and a long pin (on the right). The long pin is the ground pin, as can be confirmed by determining that there is a short circuit between this pin and the camera hot shoe contacts on the side of the hot shoe mount.

Turn the power pack off and remove the batteries. Saw off the segment of the plug at the square end of the plug containing the 0v pin, flush with the surrounding plug material. Round off the corners of the remaining square section so that both ends are rounded in the same way as the AF-540FGZ socket.

Cut the powerpack cable at the straight section, and bare suitable lengths of copper on the black and red wires on the power pack side, and the Red and White wires on the socket side. solder the powerpack-side red wire to the socket-side white wire, and the powerpack-side black wire to the socket-side red wire. Use heatshrink sleeves to isolate all wires and to reinforce the cut section.

You can now power up the power pack, and check that you have 330v across the two remaining pins on the socket, with the ground pin now being the one that was rounded from the start.

The plug is inserted into the AF-540FGZ with the cable extending towards the subject with the flash mounted on a camera, or to the left when looking down the axis of the plug (it doesn't fit properly the other way, which is why I reversed the polarities). It is of course a good idea to further modify the plug to include an indexing element so that it can only be inserted with the correct polarity.

With the modified TR Powerpack, my AF-540FGZ cycles in 4 seconds instead of 7.

Have fun.

Sparkston