Have a unit here that operates properly when on Inspection. ECD shows Code 90, operates fine. PLace on automatic, ECD shows a code 50 (no start signal) and a code 90 (power loss). I have all voltages, 24vac, +24vdc, +5vdc. I am suspect of a Main Board problem but am not a fan of replacing boards unles I am positive it is warranted. Anyone know what causes a Code 90? Feel relatively that the code 50 is a result of the code 90.
Thanks in advance for any assistance. Slider.

Apologize all. Been a long day.
On automatic, it gives a Code 50 and a Code 99 (Power Loss). Question is concerning the Code 99.
Slider

Do you have a service tool to plug into ? You might get more info under event log. What type of starter is it ? Allan Bradley? Are the main contacts pulling in then dropping out or do you not even make it that far? Also what version software do you have on the CPU? 1.5,2.0,2.1?

you may have a bad key switch. One of the 50 code causes is the start switch did not return to center within 10 seconds. Another is there is no start signal for a time period greater than 1 second while the start switch is not in the center position. i would look here before replacing a main control Bd. Does it do the same thing at top and bottom Key Switches?

If your getting a power loss fault check the wires going into the terminals of the power supply, had one randomly turning off and found the terminals were loose. Hard to tell if they're loose with the miles wrap around it

Apologize for not closing this out but problem was the main CPU board.
Anyone got any KONE E5000 comb impact adjusting procedures