Conventional Fixtures - Lamp woes

[FMEng]

I just encountered some weirdness. I replaced a couple of burned out FEL lamps in our trusty, old Strand lekos. I put in two new Osram FELs (made in Mexico), and neither worked. I noticed they felt very loose in the socket as I put them in. I tried one of them in a third leko, and same thing. An ohmmeter shows both have filament continuity.

I swapped them for Ushios and they work. They feel properly snug in the socket too. The burned out lamps showed no signs of arcing or pitting on the pins, and the sockets look clean and shiny.

Without dragging out the calipers to measure, I'd say the tolerances on the Osrams are crappy. Aren't there supposed to be standards for these things? It appears I'm stuck with a half dozen unused lamps that are worthless. I have had them in inventory for a couple of years so I can't return them.

[gafftaper]

If you got them from a local dealer (PNTA?) they may take them back anyway just to keep you a happy customer. You could also take this straight to the manufacturer and call OSRAM and complain.

[Les]

Seems like I have had a similar problem. I have an old Altman 3.5Q with the old style lamp base (before the heat sink version), and it will only fit certain types of lamps. GLA's fit just fine, but I tried some other lamp (not sure of the code, but it was a 575 with the large filament structure like that of a FEL) and it would not fit. I noticed that the lamp socket's corners were more rounded than the base of the lamp and the corners of the lamp were too sharp to allow it to fully insert. This lamp had an all-ceramic base and my GLA's have the metal base. I just chalked it up to needing a more modern lamp base and moved on, but thinking over the situation, it's a good thing I don't have 50 3.5's and 75 of the ill-fitting lamps!