HP-41cx "plastic film" in battery contacts

[Giovanni Jimenez]

Some time ago I got a nice HP-41CX, and I noticed that there is some sort of "plastic film" covering the contacts in the battery compartment; not all of it because the calculator works fine, so obviously the batteries are making contact, but it is around these contacts and I have no idea what this film is for. It is a bit loose but I don't want to take it off, just in case it has some purpose.

I have another calc (HP-41CV) and it doesnt have that "film".

Any idea what this might be ? THX

[Eric Smith]

Hard to say without actually seeing it, but is it possible that the flex circuit is delaminating?

[Geoff Quickfall]

I would have to agree with Eric. Having now fixed two of these, both suffering corrosion damage there are three layers.

The film the gold is bonded to and a film that covers the gold contact. This film is bare at the contact points for the batteries and the module connections and can delaminate. As long as the gold is intact and not cracked there should be no problem.

I suppose you could glue the plastic back in place with contact cement ensuring you clean any access but it is not required.

Cheers, Geoff