The actual temperature in the probe is shown on top. If regulated within +/- 0.1°C of the preset temperature the green VT light is on, otherwise it blinks.

The lock level is indicated on the white scale ranging from 0 to 100.

The lights below show whether data is acquired (ACQ lights up in yellow during FID acquisition), LOCK and SPIN light up green if sample is locked and correct spin rate is achieved, PFG lights up in red when a gradient pulse goes to the probe, RCVR OVFL in red indicates too much receiver gain.

CHANNEL XMTR lights up yellow when r.f. pulses are sent to the probe (channel 1 for proton, 2 for carbon), [3 for nitrogen, i600 only].