You're not touching the fixture with the lamp lit are you! Gasp! Sadly, this is a problem with virtually all Fresnels, due to the way they focus with lamp and reflector riding on a sled that moves to and fro the lens. Screw-feed Fresnels are only slightly better. The FRK's filament looks as robust as they come, with the famous "four source" segment design. Does the sled move freely on its guide rails? Perhaps lubricating with some powdered graphite could help.*Any little bump while focusing, and out goes the lamp.
It must be just you!
I guess I may have gotten a bad lot. They're all USHIO, FRK JCS120V-650WC. They all seem to go in the same or similar spots, so maybe its worth trying a fresh batch. It doesn't take much either. If they are warm, at all, we have to be careful during any focus adjustments. A kid runs the sled too far and bumps one end of the track or the other...blink. Bump the housing with a barn door...blink. I've never come across anything like it. I'm used to my 65Qs that are a lot more rugged compared to these, so I figured I would check.
Calling @ship @DELO72 This post's right up your alleys.Hi folks! I inherited some Selecon Acclaim fresnels and have found them quite handy in our space. Does anyone know if there is a lamp that could replace the FRK 650W? The filament is incredibly fragile at operating temp. Any little bump while focusing, and out goes the lamp.