Recently, Sean Ras posted:

I have trouble getting my Canon EOS 10D to properly fire my White
Lightning X1600 via the PC sync cable. White Lightning tech support
believes it may be because the sync polarity of the cord is center
positive while the EOS 10D PC connection might be negative. Does
anyone know the sync polarity of the EOS 10D? I can't find that info
anywhere. This is a description of my problem:
I just purchased an X1600 and I'm having trouble with the unit firing
sometimes. I use a Canon EOS 10D or a Mamiya C330f to shoot.
Sometimes, the X1600 will not flash when I have the sync cord
attached to my camera or flash meter (Minolta Autometer IVf).
Suddenly, the flash will begin to fire and everything starts working
fine. I'm not using any different settings on the camera from the
time the flash doesn't respond to the time it does respond. My best
guess is that there is a problem with the sync cord so I'm going to
purchase a new one as soon as I get the chance. Are there any other
things I could check that could possibly cause this type of problem?
Thanks for your help.

From your description, it doesn't sound like a sync polarity issue to me.
If it were, most likely it would never fire.

I'm not clear as to whether the X1600 works reliably with the C300f but
not the 10D, or whether the problem is independent of what camera or
attachment you use. If the problem persists regardless of the camera or
attachment, then it's most likely a problem with the flash trigger
circuitry.

Since you've said that it starts working properly after the flash has
fired, perhaps the X1600's trigger circuit needs to be "initialized" by
firing it a couple of times. If this works, then the problem may be
"cured" by using a properly grounded outlet. If you're already using a
grounded outlet, then it's probably a design issue that you won't be able
to fix yourself.

Regards,

Neil