PT-020 and a Broken Bulkhead Connector

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You are obviously at this page because you've either sheared the plastic section of the bulkhead connector or you've broken one of the important pins in the connector. If you fit in the former category, this page may be for you. If you are in the later category you still have another choice....

I'm in the latter....what's my other choice?
Well, I'm guessing you've broken the pin when connecting the mike-dive bulkhead adapter? If so, you are in good company. The pins are very fragile and easily damaged. Michael does state this in the documentation he provides with his solution. Personaly, I'd say this is a design flaw of the PT-020 and not of Mike's solution.
Now the good news - only 3 of the pins are actually used. The other 2 are redundant. If you look at the connector from above, with the camera port facing away from you (as if you're taking a photo) the pins used are in the 5, 10 & 12 o'clock position. If you've broken the pins at either 2 or 7 o'clock then you've no worries as they aren't used!

I've broken either the 5,10 or 12 o'clock pin, what else can I do?
You can always use the through housing infrared adapter that Matthias Heinrichs produces. This couples the external flash to the camera using infrared beams. I'm led to believe it's a little more fiddly to get set up and aligned properly, but is very good in operation. Another alternative is to re-polarise the plug and socket. This can be easily done by removing the plastic lugs in the socket. You will then be able to rotate the TTL adaptor and the external connector cable by a 5th of a turn so that the broken pin is effectively in an unused position. Obviously, you will need to make new alignment marks for the internal and external connectors but this is far from rocket science.

I've broken the red plastic bit. What can I do?
You have 3 choices....
1. plug the hole and use an IR. adapter
2. buy a new housing
3. replace the bulkhead connector with something a bit more substantial
4. get a new bulkhead connector from Olympus

Eh? I thought you said there were only 3 choices?
Well, option 4 is like obtaining the proverbial rocking horse sh*t

OK, tell me about option 3
Very Important Notes:
1. This procedure is not reversible. Once you've cut the threads that's pretty much it. But the, you're here becuase you've broken the bulkhead connector right?
2. The page presented here is for replacing the bulkhead on the PT-020 housing in conjunction with the Mike-dive wired strobe solution for Sea & Sea strobes. I do not know if this will work with the Nikonos connector strobes as I am not familiar with the number of wires / pins used on this range of strobes.

Back to Option 3.....
This is relatively straightforward to do as long as you have the correct bits and pieces. The most important piece is the cable gland you require to allow the cable to pass through the housing bulkhead into the camera. For this, you will need a chromed cable gland rated to IP68 and has an M12 thread on it. Both of the glands I obtained are M12x1.5 (the 1.5 being the thread pitch which equates to 1.5mm between threads) and suitable for cables between 3 and 7mm in diamaeter. You can use a different thread pitch, but it is important that the gland is M12 and will suit a 4mm cable.

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In addition to the cable gland you will require some epoxy resin and a tap to cut a thread on the housing. The tap needs to match the gland. In my case I used a 12x1.5 tap (bought in a set from eBay for £10).
The gland can be a bit more troublesome to obtain. I got one from a local electrical wholesale supplier, which would cost about £2.50. The other, Michael was kind enough to send to me.

This one was the same as the ones he uses for the strobe connector block

Cutting the thread
The reason we use the M12 gland is that to cut the required thread in the housing means the existing bulkhead hole doesn't need to be altered. You simply remove the broken Olympus connector in its entirety. Having never cut threads in anything since my school days (20+ years ago) I was going to pracitce on a spare piece of polycarbonate just to see if I was still as cack handed as I was in school. In the end I couldn't be bothered and just attacked the housing.



As it stood, the housing was next to useless so the risk wasn't that great. Cutting the thread is pretty straightforward. It's simply a case of turning the die 1/8th of a turn at a time, working it back and forth a few times to remove the excess material then turning a further 1/8. This may not be the fastest or best method, but it worked for me and I didn't crack the housing. In total it took about 5 mins to carefully cut the thread. The hardest part is making sure the cut goes in absolutely vertical....a few practice runs on spare plastic would be worthwhile if you've not done this before. Once the thread is cut, carefully work the die back through the thread then clean all the excess plastic shards away. To make things easier for me, I left the housing closed, consequently lots of bits of plastic ended up trapped inside.




These, quite obviously, need to be carefully removed so as not to foul any o-rings etc. You may find it is easier to have the housing open to avoid this minor inconvenience.

Inserting the gland
Once that is done, you can offer up the gland to check that it fits the newly cut thread. The gland should have a sealing o-ring at it's base. This should be removed as we will use epoxy resin to seal the thread to the housing. You need to be able to screw the bulkhead connector in tight, but not so tight that you strip your newly created thread. At this stage, you need to pluck up the courage to cut through that nice strobe connector cable. You can either cut directly through the Sea & Sea cable (not recommended) or cut through the one that Michael supplied.

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Now it's a case of threading the cable (after cleaning) through the gland, leaving about 80-100mm of cable to play with, and tightening the gland as tight as you can with spanners. It is important to do this now becuase when the gland is epoxy'd to the housing, you won't be able to get a good grip on the gland and risk breaking everything.



Now is a good time to prep the cable and strip the outer sheath as close to the gland as you can.



It's probably not necessary, but I elected to fill the void with epoxy resin as insurance against the IP68 seal, for whatever reason, failing.
Finally, we load the entire thread of the gland with epoxy resin (no photo of this as I was using Araldite Rapide which sets in a few minutes) and carefully screw the gland into the housing as tight as you can by hand only. The resin should overflow up and around the entire base of the gland.



If it hasn't, now may be a prudent time to build this area with resin whilst it is still liquid. This will not only lock the gland in place but should stop any water ingress as the thread should be completely sealed.

Wiring the Cable to the TTL converter
Mike has been a star with this part as he has kept with a consistent colour coding for the cables. What follows is certainly true for the Sea & Sea connector, but will need verifying for the Nikonos plug. The colour coding that Mike has used is as follows:-
White - Trigger
Brown - Ground
Green - TTL quench

Prior to knowing this, I sat down with a multimeter and mapped the entire set of connections from the TTL adaptor to the strobe itself. Starting at the TTL adaptor, there is a flat, 3 core cable that terminates in the 5 sockets that plugged into the bulkhead on the inside of the housing. These map directly to the 5 pins on the outside of the bulkhead. The pin at 12 o'clock is the trigger, the pin at 5 o'clock is ground and the pin at 10 o'clock is TTL quench. Working these back to the flat cable...the middle cable is ground. The cable closest to the middle of the TTL adaptor that plugs into the camera is the Trigger and the cable closest to the edge of the adaptor is the TTL quench. At this stage, you have 2 options. Either remove the small PCB that used to connect to the internal bulkhead, or leave it there and push the wires from mike-dive cable into the holes. I chose the latter after tinning the wires with solder.
To cut a long story short, the White wire goes to the 12 o'clock hole, the Brown wire goes to the 5 o'clock and the Green wire goes to the 7 o'clock.

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