Agilent Technologies 6890 Series Service Manual page 726

Testing resistance of the heater coil
If you believe that your heater coil is cracked or otherwise damaged and has
caused an open circuit, you can check it by measuring its resistance.
To measure the resistance:
1. Turn the instrument power off.
2. Disconnect the oven heater leads (P3, P4) from the AC power board.
3. Use an ohmmeter to measure resistance at the connectors.
Acceptable resistance ranges (in ohms) are given below. Acceptable
resistances range from the nominal value for a new, cold heater to +5% from
the nominal value.
Note Resistance goes up approximately +3% after heating the coil.
Table 1230-5
120 V
200 V
220 V
230 V
240 V
n/a = not available
Jun 2001
Resistances of the Heater Coil
Nominal cold heater resistances
Standard oven Fast-ramp oven
(1600 VA) (2250 VA)
9.07 – 9.52 Ω
n/a
17.78 – 18.7 Ω
n/a
21.51 – 22.6 Ω
n/a
33.06 – 34.71 Ω 23.51 – 24.7 Ω
25.60 – 26.9 Ω
n/a
Electrical
Agilent 6890 Gas Chromatograph Service Manual
Power Supply
Testing resistance of the heater coil
1230
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