HP 54603B Scope: Softkeys under the display don't work, locked?

[marcopolo]

Hi,

I got 4 x HP 54603B digital scope from a school and the 6 softkeys under the CRT display don't work (same problem with all scopes)

I think this is a special function for use in educational environment. How could I remove this protection?
(or all the scope are not working)

Thanks,
Marc

[Wuerstchenhund]

This isn't a lockout (and it wouldn't make much sense anyways), it's very likely the keypad just stopped working due to dirt/age. You can get it back working by opening the sclope, removing the rubber membrane, cleaning it with alcohol and then re-paint the rubber contact domes with conductive paint (search ebay for 'remote control repair').

[james_s]

I've repaired a LOT of rubber membrane keypads that weren't working and I've never once had to repaint anything. I simply wash the rubber membrane with warm water and a bit of liquid dish soap, give it a good scrub with my fingers, rinse it off and set it out on a towel to dry.

[bd139]

Might be cracked. Usually the first thing to go if they are dropped. Had one of them. Repair thread here https://www.eevblog.com/forum/testgear/hp-54602b-oscilloscope-problems-repair/

Mine was unfortunately a write off due to the main board being cracked

[james_s]

Either way what I would do is take it apart, wash the rubber membrane, and while that's drying inspect contacts carefully for damage. I fixed a cracked membrane strip on an older Tek scope with some carbon paint, I don't know what HP uses but Tek has the button pads printed on one of those thin flex PCBs that is stuck to the aluminum frame around the display.

[marcopolo]

I simply wash the rubber membrane

Done, the first scope works again (no lockout)

Thanks,
Marc