RADIOMETER TCM3 - Page 74

2.
TCM3 TCM3
and
TCM30
Service
Manual
Main PCB, Continued
“BAT” Light The display segment “BAT” will be activated if the mains adapter or the battery
Bar Control cassette is removed, informing the user that there is only a limited power
available.
This function is controlled by the comparator QASa, the output of which will go
low if the power supply voltage (Ext. Pwr. Sense) drops to below 7.8 volts.
If the NiCd battery unit is discharged to 7 V, the LBR (Low Battery Reference)
terminal of QA1 will pass its reference level of 1.3 V, and LBD (Low Battery
Detect) will go low and activate the Light Bar Flashing Programme.
R14 between Low Battery output and input, gives the function a certain hysteresis.
Test Points The PCB includes the following test points: -
Test Point Signal
TP1 TX serial data
TP2 RX serial data
TP3 +5V
TP4 Ground
TP5 Heat supply voltage
TP6 A short-circuit to ground will produce a permanent BREQ.
(For special test purposes only)
TP7 Potentiometer adjustment (factory adjustment only)
TP8 RAM supply voltage
«mnono +