Need some small button micro switches. These have worn out.

Thread Starter

sdowney717

Joined Jul 18, 2012
648
They tell an HP 4000 laser printer what size paper is in the tray by means of levers pushing on them.

Does anyone have a link I could order some, or can they be cleaned? There are six white switches.
s-l1600.jpg
 

dendad

Joined Feb 20, 2016
3,602

Thread Starter

sdowney717

Joined Jul 18, 2012
648
I totally owned those 6 switches, they all are working well now.
I cleaned them first with a rust buster oil solution which is slightly acidic. Kind of like PB Blaster but made by some one else. Came in a little squeeze can, and must be decades old stuff.
Soaked them, twisted their little tops with a hemastat and pushed them on and off till they started reading ohms.
Them I soaked the board in rubbing alcohol, repeated the oil treatment, then alcohol again.
Then I dried the board in front of a forced air heater.
They work fine again.

Taking apart an old HP 4000 laser jet printer is no fun, and the old plastic cracks easily. PVC pipe glue works fairly well to fix that kind of plastic.

The error in case anyone comes here googling was unexpected paper size, and the problem is the paper size board does not tell the main board the proper paper size as the switches do not work. To get to that board, the entire printer has to be taken apart, removing the top laser and gears housing as a unit from the printer base.
 
Top