Replacement timing board that has an O2 purity and pressure sensors for OXO-style oxygen concentrators, OXO6, OXO8, OXO10

The concentrator will never shut itself down due to purity or pressure issues. The only 3 ways of actually turning off the machine are by flipping the power switch, unplugging/disconnecting either the power cord or wiring harness from a terminal, or if the circuit breaker/thermal switch on the compressor were to trip. Outside of that, the unit will remain on, but will produce a loud audible alarm to notify the end-user of the issue. I do not know if I covered it in the past, but the LED lights on the 8400-1304 board correspond to the performance of the concentrator:

Flashing Green LED (Top LED) – Denotes that the machine is on & currently is building up its purity for use.

Solid Green LED – This will illuminate once the unit has reached at least 87% purity, and is good to begin using.

Flashing Yellow LED (Bottom LED; Alarm Function) – This indicates there’s a pressure issue; our circuit board’s pressure sensor has an operating range of 4.0 – 29.0 PSI. Should the pressure dip above or below that mark, this LED light will turn on & an alarm will let you know. Generally this means there’s either a leak somewhere, or something isn’t connected (like tubing).

Solid Yellow LED (Bottom LED; Alarm Function) – This light is designated to the oxygen purity of the system, and will turn solid yellow if the oxygen purity has dropped below 87%. This one has numerous causes, but can be usually traced back to either a low output compressor, a leak/disconnection, or an issue with the sieve bed itself.