This is the adapter when it comes to you. Note the two empty holes - you`ll need to solder two wires there from the flash. Doing so there are no worries about isolation of wire-wire-connections. Let`s go - after this last warning:
WARNING!
Inside the flash there are dangerous high voltages (300V DC!) - even after the flash has been switched off and batteries are removed. Be careful when assembling the unit and don`t touch anything other than the mentioned parts. For a little more safety fire the flash with the TEST button and immediately open the battery chamber. Doing so will discharge the flash cap mostly. But some charge still remains - be very careful!
Remove the four screws at the bottom of the flash. Now lift the flash gently on the back. You`ll see some connectors inside. Remove the blue (3 pins) and the white one (6 pins) besides it. It`s impossible to connect them wrong, if you`re unsure, mark one side with an Edding or something like that.
Now lift the bottom a little more. There`s another connector from the AF illuminator that needs to be pulled. Now lift the bottom part completely and move the flash away. The assembly will be done completely in the socket.
Wireless receiver (the PCB with 3 wires connected, most left picture) and AF illuminator are fastened with two screws each. Remove the screws and lift both parts. Under the wireless receiver you`ll see the parts of the retention mechanism, remove them (otherwise they will drop to the floor, believe me ;-)).
The picture on the left side shows the solder points we`re dealing with. Unsolder the green and the black wire. The black one is a little difficult as some plastic from the bottom part is in the way. These wires are now soldered to the adapter PCB - black besides the red one, green to the purple. The green and black wire from the adapter have to be soldered to the socket. Result is shown in the right picture.
Now we`re coming to the red and grey wires. They have to be soldered where red and grey wires are already connected to the flash socket. I did solder them to the appropriate flash connectors - more easy than to hassle with 3 things and two hands...
Finally, connect the yellow and the purple wire. They have to be connected to the wireless receiver. Yellow goes to (guess, eh?) yellow - and purple to red (didn`t want to confuse you by two red wires on the adapter).
And that`s it! Now reassemble the unit by first putting the AF illuminator in place and fasten it. Do the same with the wireless receiver. The adapter PCB fits best on the back of the receiver, use some scotch tape to fixate it a little. Put the wires anywhere you like to in the socket, but leave the space beneath the wireless receiver empty - the retention mechanics takes place here.
Now your flash socket should look like the one on the picture. When installing it back to the flash, first connect the AF illuminator, put the socket on the flash and connect the other connectors. The PCB has been designed to fit quite well inside the flash.
You should not try to test with open housing. This is because of the high voltages in operation and for the quite short wires from flash to socket. In addition, you would have to release the flash without using the release button.
On 5200i purple wire is ommited due to the missing wireless receiver.
The yellow wire is connected to one of the connectors on the flash for the same reason. The picture on the left shows the connectors found in an 5200i. Yellow wire has to be connected to the pink one showing on the most right connector in the picture.
On the 3500xi, purple and yellow wire are connected different as well. When removing the basement, you'll see the PCB shown in the picture on the left. Under the white connector (unfortunately it's not removable...) there are two vias. Connect yellow to the left, purple to the right one. Be careful not to damage any wires or the
connector with your soldering iron! Scratch the solder stop with a small screwdriver or knife, apply some flux and solder, and connect the wires. This is a bit tricky, but works. Sorry for the picture, but I don't have a better one. Maybe somebody sends me a version of his/her modification?
And now - have fun and don`t forget to tell me your results and show pics! They are kept confidential ofcourse ;-)