Paul C. Buff, Inc. Technical Forum

I recently purchased two additional 640s. When I plugged one of them to set it up in my studio it would not flash. I called tech support and they had me swap out flash tubes with one that was working. Still no flash. They sent me out a replacement that day (Thanks!). The problem is now with the unit that I took the flash tube out of. It's back in and appears to be seated correctly...prongs are straight and won't push in further...but now that unit won't flash. Are the flash tubes that sensitive that swapping them out could have damaged them? No I did not touch the bulbs with my bare hands. I don't want to put too much pressure on it trying to make sure it's seated correctly. Any help/suggestions would be greatly appreciated.

Generally, no, the flash tubes are rather durable. Touching them with bare skin would not likely cause an immediate failure (but will shorten the life). If you are not doing so, use the test button on the flash unit itself, as well, remove any remote controls from the unit, even if you are not using them for triggering.

If that tube was known to have worked before the current installation, check the glass for any cracks or breaks. Check the metal connections for any breaks, particularly the band that goes around the tube on the trigger leg (the leg that would be at the bottom, away from the two legs close together) as well as the legs themselves. Also, check closely that the legs all went into thier corresponding eylet in the light. The trigger leg can sometimes miss the eyelet, and bend and rotate so that the flashtube appears straight.

On a properly installed flsah tube, the trigger leg and the band that goes around the tube will have the shape of a lollipop. The band is centered and on top of the leg. This is opposed to a shape of the letter "p" or "q", where the band is to oneside or the other.

Maybe a couple pictures in a FAQ would be worth a thousand words here, and for general info too?