Troubleshoot Nissin Di 466

I have a Nissin Di466 that is behaving. I don't know how to troubleshoot.

When I put my camera (5D) on P mode, or green box and I use the Nissin Di466 flash, I get images that are really dark. The histogram (show image in the camera, then press info) is non null only in the left half.

When I try the exact same setup using another flash (YongNuo) the image is well exposed (the histogram spread across the entire range).

The batteries are fresh. Both flash point in the same direction, etc.

I don't know what else to test, do you have any suggestions?

Is this the symptom of a dying lamp, dying capacitors, else?

Thanks

IMAGE LINK: http://s954.photobucke​t.com …i466_zpsead7fe8​8.jpg.html

More relevant information may help?

The problem is consistent. Always underexposed (first shot after opening, first shot after a waiting time, series of shot, etc.).

I don't use exposure compensation in the camera.

I don't adjust the flash power (although when I boost it to +1.5, exposure is somehow correct, i.e. is what I would expect without boosting it).

I use TTL mode on the flash.

The flash is directly connected to the hot show.

Let me know if something is not clear, I will add the relevant details.

Best regards,

wallace1837 wrote in post #17295619
More relevant information may help?

i realize this is a world wide forum, but most, if not virtually all of us over here in "the states" are with family and friends on Thanksgiving holiday. Might get more response come monday.

It's hard to tell if the flash is firing at all?

Have you tried it in manual mode? Try full power to see if it will blow the scene.

Do you have remote triggers? Might try them to help start the process of narrowing down the problem.

Hi,
Thanks for the cultural update.

The flash does indeed fire, it is just weaker than it should be. I can increase the flash power, but I need to put +1.5 on the flash to get what I think is right. During that time the camera is either on P mode or "green box" with no over- or under compensation (in the camera).

So I guess, I want to "debug" this under powered flash.

Happy thanksgiving

Hi!
I suppose that is time to replace the xenon tube. Especially if the flash is more than 2-3 years old.
Say, please, how works Nissin in the manual mode? Exposure is normal? The flash power level is adequate to Guide Number table (in "Instructon Manual")?

VicHelis wrote in post #17297201
Say, please, how works Nissin in the manual mode? Exposure is normal?

Yes this ^. If with the in manual mode and full power the flash is very bright then the problem is likely with the communication between camera and flash.

I've seen other comments that say certain flashes need to have flash exposure compensation dialed in all the time. Usually only two thirds or one stop, but it's not unprecedented.

It is more likely that with worn-out xenon tube the metering pre-flash impulse in E-TTL mode is a little longer than should be. As a result, the camera computer incorrectly assumes that the subject is too bright, and reduces the main impulse to prevent overexposure. So pictures become dark.
However, in manual mode, worn tube until it dies completely, working almost normally.