what is the test?
fixed number of cycles?
fixed number of hours?
cycle till the switch falls apart?
Inspect
Remove batteries as they are not used for this test. Very carefully take meter apart as to not disturb contact area. Document the switch area with a camera and note any lubrication.
Prep
Select contact and locate places where 30 AWG solid core wire may be attached at least one inch from switch to avoid any possible damage to switch pads. Using about 6" of wire per test point. Route wires outside of case without placing any strain on the case. I have been going through the battery cover.
Pretest
Attach external meter and measure the DCR with the switch closed. Select which fork to use based on selector switch size. Determine where to program the stepper to allow the function switch to fully rotate.
Cycle
The switch is fully rotated both directions to complete one cycle. Each switch will be cycled 50,000 times. Note, if they are intermittent, I will continue to cycle them but if they go full open (1000 cycles with no resistance), I will abort the test. If they grind to dust, I will continue the test as long as the switch continues to have some measureable resistance when closed.
Final Inspection
Once the meters have been cycles, I will disassemble them and document my findings. I plan to use the microscope to capture the problem areas. I am interested in metal particulates trapped between the contacts and cut traces more than anything as these could pose a risk. At this time, I have no plans to incrementally pull the meter down for inspection prior to fully completing the cycle test to avoid any contamination to the test.
The software obviously records the contact resistance and I have a few different metrics that I plan to use to show how each switch wears.
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This is a VERY LONG and time consuming test to run. We are measuring fairly low resistance so the meter takes time to settle and you can't cycle the switch so fast that the plastic starts to warp or melt. So it's the slow easy pace.
I wonder if the 17B+ will be useable after this many cycles.....