MAX77714 - Why Would a Push Button Fail

RE: MAX77714 - Why Would a Push Button Fail

kmikemoo — Tue, 28 Sep 2021 17:38:14 GMT

[mention:0d133614bf01463a9e17ef49e25b2c0b:e9ed411860ed4f2ba0265705b8793d05] It's amazing how little oxidation it takes to goof one of these little switches up. My last experience was the reverse - it made intermittent contact when the button wasn't pushed. Resistance readings were in the low kilo ohms. i did measure the replacement before soldering it in - and threw out two more switches in the process of selecting the replacement.

RE: MAX77714 - Why Would a Push Button Fail

dougw — Tue, 28 Sep 2021 16:37:36 GMT

The way that schematic switch symbol is drawn, you would need to connect pin 3 to pin 4 or pin 2 to pin 1.

These connections are usually inside such a switch, but the symbol doesn't show it.

Perhaps worth checking if pin 3 is connected to pin 4 and pin 2 to pin 1.

RE: MAX77714 - Why Would a Push Button Fail

ralphjy — Tue, 28 Sep 2021 15:28:53 GMT

Not that it's your problem, but that's really an odd schematic symbol for your switch.

I would do a close inspection of the switch attachment. From your picture the solder fillets on the pads don't look very good. It looks like the switches were manually soldered rather than reflowed. That could be a problem getting good attachment with a J terminal.

RE: MAX77714 - Why Would a Push Button Fail

fmilburn — Tue, 28 Sep 2021 15:17:25 GMT

Strange. You may have already done this but can you jumper across the switch contacts with wire and see if that causes reset? What happens if you buzz for continuity when the MCU isn’t powered and push the switch?