Design MPF socket corrosion: this has got to stop .

[gafftapegreenia]

Just had to rehang two more 6" Fresnels this morning due to socket corrosion. I know this has been a problem for other people, but this is the first time I myself have ever had to deal with it this bad. WHAT is going on? I read something on here about the center lamp contact being redesigned, is that really to blame? Are there brands that haven't switch to the smaller contact?

What is the feasibility of dumping the MPF socket and making a 65Q into a "studio Fresnel" with a medium TP22 socket?

 

[Beans45601]

How old are your instruments? No socket will last forever and you should plan on having to replace them, eventually. My Strand Fresnelites, made in 1988, just had to have all their sockets replaced. I'm not too upset about having to do that once every 24 years.

 

[BanditRO]

Ran into this previoiusly. Are you using Philips lamps in the fixture??

Changing to a TP22 might be possible, unlikely one would get the same quality of light as the filament layout, LCL, etc. may not be easily matched...

 

[ship]

Many times gone into specifics on how to resurface a better described as P-28s socket on this website. Following the steps, you get about 90% saving of the lamp sockets I find and have done over a few hundred having done so. Cracked socket, warn spring or too pitted from arcing to save the main reasons for replacement I have seen.

Now there is two types of lamp out there and it could be older style verses newer style in all having gone to a center say pebble for contact on the hot. The other one has a plate that allows more surface area to conduct, but has solder blobs often getting in the way of a plate to plate contact. The more pebble center ball like concept is probably slightly longer in length in exchanging surface contact area for a little more tension on the spring so as to achieve the same good contact. I think this a bad concept. Still a smaller surface area conducting and more pressure equals in a small area more heat. But I think it mostly normal - how large that pebble in area is might be a design thing between brands though in some better than others.
Have not looked into it. Before each show, all lamps removed and inspected with flash light and inspection mirror to the base, plus looking at the socket of the lamp. This is a thing that can otherwise be looked at in yearly maintinence - how does it look at the socket and lamp tells all and is preventive.

Should there be a problem, possible to save both socket and lamp, and you have to do both. You are also looking at overheating of wiring and other problems inside the fixture by the way with that inspection mirror.

Final note, for some reason, P-28s lamp sockets have changed over the years. They are larger and I believe the mounting holes are different. Not a huge problem but a detail in why the old socket often can be repaired in perhaps even cheaper to do so.

Converting P-28s to G-22, not likely it will bench focus properly but possible. I know I have converted over the years many Euro fixtures with non-convertable lamps to 120v versions where possible. If the LCL of the fixture is longer than the lamp in base is now, easy enough to add spacers under the lamp socket. Normally though it's a EU fixture converted to US I have been able to do, have not looked much into the reverse. Not really gaining anything anyay in converting to a different lamp.