HP33E repair

[Krauts In Space]

(01-08-2018 02:06 PM)jebem Wrote:  My calculator do not use that yellow layer. Is that a foam?
Probably installed to stop the keys to jingle around.

I understand there are at least two different variants of these machines, where some use solder-less technology where the IC chips are just doing contact with the PCA by means of pressure (like mine here) and others uses a more traditional soldered chips.
Is yours using solder-less chips?

All chips seem soldered.
And yes, the fabric seems to be some sort of foam.
Mine has 4 pins that lead through the fabric, keeping it in place.
To me it prevents that jingling and it covers/protects the electrics.
Not much improved since the 1980s to modern low profile keyboards

Solderles electronics? No corrodings?
Sounds not very reliable to me, but over decades working calculators prove me wrong ^^