Leica LTM Leica III with PC socket troubles

[Mr_Flibble]

A couple of months ago I got a Leica III with one of those ugly aftermarket PC plugs sticking out of the top cover between the RF and VF.
When someone else asked about about a camera with this modification (it was Ron in another topic I believe), I asked for a good hand-held flash to use with mine.
Someone else suggested getting a Vivitar 283, which I did through the give-away thread in the Members-only section.

5 Euros later for a Vivitar-to-PC cable, I discover the flash doesn't work with my Leica PC socket, but it does work with my Kiev 2a and Konica S2 Auto.

So what are the possible causes?
Is the central pin on the PC plug too short? Where these longer on older models?
Or possibly something else has failed so the circuit isn't closed when firing the shutter and flash?

So currently I'm stuck firing the shutter on 1/sec or B and firing the flash by hand 🙁


The flash is a Japanese-built Vivitar, some of these were said to have a trigger voltage as high as 600v!...so better not use it on my R-D1 huh 😉

 

[ZorkiKat]

A rather offbeat assessment: is the synch circuit in the Leica working? In many cameras I got, those which did not synch all had broken circuits. Cases where the wire broke off or corroded, contacts dirty, etc.

Added synch circuits are more prone to this. Having no real synch switches within, the adapted circuit is often built around (and often use) exisiting parts. In my synched Leica IIIc, the closing contact is on the 2nd curtain releasing lever. Added and fabricated parts can go loose and fail.

 

[Mr_Flibble]

That sounds like the most logical cause to the problem, I'll need to get my circuit tester back from my dad. Will see to it this weekend.

 

[John Lawrence]

On one of my IIIs the aftermarket pc sync socket was deliberately disabled at some stage in the past.

 

[John Shriver]

Also, note that the PC socket is (or was) probably FP sync, not X. Modifications would be needed for X sync, to trip when the first curtain is fully open.

 

[Mr_Flibble]

I assumed it was an FP-sync. but I expected the flash to fire with the shutter set at any speed, but in this case it doesn't fire at all.

I also assumed releasing the shutter at 1/60th of a second or slower would allow me to use the vivitar instead of a bulb-flash (which I don't have)

 

[John Shriver]

FP sync fires the flash before the shutter opens, to give the flash bulb time to get going before the shutter opens. Used electronic flash, and the flash will probably be over before the shutter opens.

 

[payasam]

The flash won't work unless the camera is set up for X sync (no delay).

 

[Mr_Flibble]

Thanks for explaining that. Ah well, as soon as the replacement foot for it arrives I guess I'll just stick it on my KAS2 or on my evil Praktica MTL50.

 

[ZorkiKat]

Actually, if the synch circuit is intact, the flash (bulb or X-electronic) will fire regardless of whether the switch is X or FP. An X electronic flash will fire at FP setting, but it will not expose film. The flash burst would have been gone by the time the shutter opens.

Leica with added synch usually don't come installed with selector switches. The synn can be either permanently set to FP (slight delay: circuit closes slightly ahead of shutter opening) or else it's X. The synched cameras I've encountered ALL had X (no delay) sync.

I believe it's easier to make X circuits rather than delayed ones. An X circuit is easily made by just looking for a suitable part to build the contacts on which would close when the first curtain clears the film gate fully. So the closing lever is often utilised as one of the contacts. FP synch making on the other hand involves looking for a portion of the part which will close just in time before the shutter opens. So this would likely explain why there are more add-on flash syncs with X contacts.

X contacts also are more flexible. They allow the use of flash bulbs as well (though at slow speeds, 1/10 sec perhaps, to allow for the peaking of the flash burst).

 

[Mr_Flibble]

Well, I guess we'll find out when I test the circuit, but it's likely that the previous owner had it disabled when he had it CLA'd (by Youxin Ye if I recall correctly)

And, Goshdarn, dad has misplaced my circuit tester. D'oh!