HP-67 bouncing keys

[Kees Bouw]

(09-28-2021 12:18 AM)GreyUser Wrote:  If you have access to an ultrasonic cleaner, a 3-5 minute cycle with a dilute citric based degreaser followed by a de-gassed clean water rinse will resolve any problematic keys.

Can you elaborate a little more on this, which ultrasonic cleaner would be suitable, at which power and temperature? Do you submerge the entire pcb including the led's or just the lower part with the keyboard contacts? Is there any risk of damage?