Shouldn't PC/Sync cords be 100% reliable for triggering the flash?

I bought this:
http://www.bhphotovide​o.com …I_One_Monolight​_Kit_.html

a monolight w/PC Sync cord and the flash fires erratically. Yes, I'm waiting for the little green light to come on.

Here's a repeatable scenario:
Turn everything on
Green light
Take a picture - flash fires
Green light
Take a picture - flash does not fire
Push test button - flash does not fire
Take a picture or push test button - flash fires

If it had a Windows OS I'd say it was locking up after the flash fired, then had to be reset or woken up in a way.

BTW another flash will set it off every time using the photocell.

Wierd. Anything I can test? Sync cord looks 100% new, seems seated properly, nothing is loose or rattling.

Replace the stock PC sync cord with one that has a Screwlock PC plug. The Screwlock PC plug screws into the camera PC port for a tighter and more secure connection.

Just so I understand, your PC cord is plugged into your camera directly, or into a hotshoe mounted gizmo? Or a wireless gizmo?
And when you say you press the test button, is that the button on the flash itself?

First guess is always the synch cord. I've had a few go out on me, and there's been no obvious visible damage. One little tug, or snag, or trip breaks the ultra-thin wiring inside.
I'm guessing the flash itself isn't bad as it works as a slave. So that circuitry is ok.

PacAce wrote in post #9501187
Replace the stock PC sync cord with one that has a Screwlock PC plug. The Screwlock PC plug screws into the camera PC port for a tighter and more secure connection.

I don't see threads on the port on the camera (50D), the current plug just slides on.

ootsk wrote in post #9501192
Just so I understand, your PC cord is plugged into your camera directly, or into a hotshoe mounted gizmo? Or a wireless gizmo?
And when you say you press the test button, is that the button on the flash itself?

First guess is always the synch cord. I've had a few go out on me, and there's been no obvious visible damage. One little tug, or snag, or trip breaks the ultra-thin wiring inside.
I'm guessing the flash itself isn't bad as it works as a slave. So that circuitry is ok.

Correct, plugged directly into the camera. Are they really that fragile? This is new.

Jeff wrote in post #9501298
I don't see threads on the port on the camera (50D), the current plug just slides on.


Correct, plugged directly into the camera. Are they really that fragile? This is new.

Trust me, all Canon EOS camera with PC ports have Screwlock terminals. If you want to check for yourself, take a close look at the inside wall of the PC sync port. You'll see the thread there. You may need good lighting to see it.

Yes, they ARE that fragile. That's why you'll eventually go wireless.
Once you determine that it's bad, cut it open and see how tiny those wires are. They usually go right as they enter the plug, but it could happen anywhere.

PacAce wrote in post #9501365
Trust me, all Canon EOS camera with PC ports have Screwlock terminals. If you want to check for yourself, take a close look at the inside wall of the PC sync port. You'll see the thread there. You may need good lighting to see it.

Found this in the 50D manual, page 114:

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The issue with the standard PC port is typically not the wire in the cord, the issue is mostly the fundamental design of the outer ring on the male PC connector.

The outer ring is split in two places to provide compliance and allow the connector to accommodate minor dimensional differences in female PC ports.

But because the ring is split it opens up with use and this results in reliability issues.

Enjoy! Lon

When I shot exclusively with sync cords we always kept plenty of extras in our bag. They will just stop working at the worst time. Our policy was once it stops working it goes straight to the closest trash can. A bad sync cord with no backup way to fire your strobes is a really bad day.

A last ditch effort solution should you find yourself in front of 30-40 people and a non working cord or wireless transmitter... Slap a speedlite on your camera, point it at your strobe, and start working in slave mode.

FlashZebra wrote in post #9502042
The issue with the standard PC port is typically not the wire in the cord, the issue is mostly the fundamental design of the outer ring on the male PC connector.

The outer ring is split in two places to provide compliance and allow the connector to accommodate minor dimensional differences in female PC ports.

But because the ring is split it opens up with use and this results in reliability issues.

Enjoy! Lon

Yeah. The PC connection is one of the most horrible electrical connections known to man. Unfortunately, it's the standard.

Wonderful I'll talk to B&H about a new cord.

Jeff wrote in post #9511404
Wonderful I'll talk to B&H about a new cord.

Check these out as well:

http://www.flashzebra.​com/screwlock_pc/index​.shtml

There are short length ones as well.

PC cables are a major pain in the rear end. They seem to fail on a regular basis. If you can go wireless. Pocket Wizards are a great option.

PacAce wrote in post #9511575
Check these out as well:
http://www.flashzebra.​com/screwlock_pc/index​.shtml
There are short length ones as well.

Thanks for the info on the screwlock types. A couple of questions though....is there a benefit of not having it screwed in? For example, if someone trips on the cord, it might come out before it topples the camera.

And, I did find the threads, dang those things are tiny, but I also took a shot (flash fired), then wiggled the connector at the camera's port and still the next shot would fail. So it seems the break is in the cord, the male end at the light or the jack on the light itself.

Jeff wrote in post #9511673
Thanks for the info on the screwlock types. A couple of questions though....is there a benefit of not having it screwed in? For example, if someone trips on the cord, it might come out before it topples the camera.

And, I did find the threads, dang those things are tiny, but I also took a shot (flash fired), then wiggled the connector at the camera's port and still the next shot would fail. So it seems the break is in the cord, the male end at the light or the jack on the light itself.

The benefit of the Screwlock PC plugs is that they stay put. If you're not going to screw it in, you might as well stick with the regular PC plugs and their intermittent and unpredictable failures. If you're worried about people tripping over the cords, and that's a very legitimate concern, my suggestion is to move up to wireless triggering, preferably RF triggers although, for indoor use, optical triggers will work just as well, too.