jcsorensen wrote:
My flash is a Quantaray QTB-7500A. Works on my Rebel, and worked well with my 10D until last week. Voltage on the Flash is about 5.0, well below Canon's limit of 6.0v. I'm thinking of putting up with the camera until after the holidays--just can't trust Canon Service when they say 15 work days.
First of all my deepest sympathies about your troubles with 10D. And I apologize in advance in case I am sticking my nose into something I don't know what I am talking about, considering I have neither a 10D nor this particular flash...
As I understand it, QTB-7500A takes an interchangeable "dedication module," much like some Sunpak and other flashes that I'm familiar with. Since you mention it works fine with EOS Rebel (film body, right?), I assume yours has dedication module "QDA-CAF" for Canon EOS A-TTL cameras.
That being the case, although I know the TTL contact pattern on the hot shoe matchs, I don't think this flash is even supposed to work with 10D. Certainly not in the E-TTL mode (which I know you know because I read your comment to my post in another thread). And not necessarily even in the manual or flash-based auto mode, as the (potentially) incompatible signals via the TTL contacts may confuse either the flash or the camera or maybe both.
(This was the case with my Sunpak PZ4000AF and G3/Digital Rebel combination, which I detailed in that other thread.)
This is only a suggestion, but I wonder what would happen if you:
1. (If this could be arranged) mount a Canon "EX" series flash on this 10D to see if you still have any flash-related problems. You might find that your external flash troubles may only be with the (incompatible) Quantaray flash.
2. If you tape off the 4 TTL contacts on the Quantaray flash and mount it on the 10D, thus blocking the non-essential signals for the manual and auto-mode flash operations, would the flash now fire consistently unlike before? (I would test this in camera's manual mode, rather than the Basic modes, just to keep things simple. This means you need to manually set both aperture and shutter speed (at or longer than 1/200 sec. for a proper flash sync.)
With the combination of a healthy 10D and such a flash (with the TTL contacts taped off), I would expect the flash to function normally in manual and auto mode. (That is, without any bells and whisles such as flash ready light and exposure confirmation displayed on the camera side.)
It does sound like there is something else going on with your 10D beside the flash issue though. So it would be hard to draw any definitive conclusions from this test if the flash still didn't work with this setup. But it just might shed some more light -- no pan intended, really.)
Again, just a suggestion for a little do-it-yourself troubleshooting, if you are in a mood for it.
Regards,