Control panel powers down
This treadmill has recently started behaving abnormally. What I see on power up is the LCDs display all segments and the 3 LEDs all display correctly for perhaps a second, apparently a power-up self test, then everything goes dark. The pushbuttons don't respond.
So far I've checked:
1. The power board under the unit. All LEDs display as per the online repair manual, and the speed LED blinks when I move the motor.
2. The cable from the power board to the control panel has full continuity.
3. There is no documentation on the keyboard, but I was able to determine that they're capacitive, and I got good readings (e.g., noticeable capacitance change) from the ones I could trace. (all but two -- power and program, and I think I nailed those also)
4. Voltage out of the regulators was good on the control panel. The three electrolytics on the board had solid 12V, 5V, and 5V.
5. The magnetic safety switch works fine.
6. The so-and-sos who built the control panel obliterated the markings on all but two of the 9 chips, so reverse engineering wasn't possible.
My gut feel is that during the power-on self test the unit discovers an abnormal state and shuts down, but I don't have enough information to take it from there. For example, a breakout of the signals on the above mentioned cable would be useful.
Naturally the online repair manual wants me to replace boards, but homey don' play dat. Besides, this is an old unit, and parts are unavailable.
Any help appreciated. Thanks!