Got a DK City treadmill from the neighbour just before he was going to put it out on the lawn for the upcoming garbage collection.
He told me it would work OK for a few minutes and then shut down.
So I powered it up and, yes, it powers up and the display panel lights up and then after a few seconds it shuts off (no display).
With the cover off, I can see that after about 12 seconds, the board LEDs light up, then shut down. Display board also shuts down. Power cycling will start the board up again but it will only stay on for a few seconds. Leaving it off for longer makes it stay alive a little longer on the next startup (temp related?).
My troubleshooting so far:
- Visual examination of all components under the hood - controller board, EMI filter, choke, main motor, incline motor. All looked OK. Motor is free/not seized.
- Disconnected all plugs on controller board - incline motor board, main motor, speed sensor?. Powered it up and same deal. LEDs stay on for 10 or so seconds and turns off.
- Pulled board out - Visual check of components looking for bad caps, resistors, damaged tracks, etc. Nothing obvious. Put it on bench with only choke connected. Powered up the AC (240V). Same deal.
- Checked diodes. Checked bridge rectifier.
- Replaced all the medium-sized (physical size) electrolytics. Didn't replace the 2 large caps (are these just for starting the motor?). They are in parallel, but capacitance measures right. Still shuts down after 10 seconds.
- Measured temperature of some components after fuse/AC with temp gun. They warm up slightly (a few degrees C), but don't get very warm before it shuts down (30 deg C). Rest of the board stays at ambient.
Is a component failing due to increase in temperature or current allowing it to stay on for a few seconds? Any clues to what component could cause this?
Where to now? Thanks in advance.
PS. Skills are limited. Only have multimeter. Being as careful as I know.