Agilent Technologies 6890 Series, Service Manual, Page: 414 / 867

3 of 20
Jun 2001
Mainframe
Agilent 6890 Gas Chromatograph Service Manual
Oven and Temperature Control 420
Oven temperature troubleshooting
Oven temperature troubleshooting
For each problem below, the probable causes and corrective actions are listed
in order of complexity/expense. The cheapest, most common, easiest to check
causes are listed first with the more complex, expensive causes following.
After identifying the problem, test for the probable causes in order from top
to bottom.
Problem Probable cause Corrective action
Oven does not heat. Faulty fuse F1 or F2 on power
supply PCB. Check/replace both fuses.
Oven heater is open. Check resistance of oven heater.
Faulty power supply PCB. Replace power supply PCB.
Faulty fuse F1 or F2 on main PCB. Check/replace both fuses.
Faulty main PCB. Replace main PCB.
Oven does not control Fast oven but GC configuration is
for regular oven.
Oven flap stuck.
Faulty main PCB. Check oven configuration.
Check oven flap.
Replace main PCB.
Oven temperature runs
away. Oven heater partially grounded. Ensure that the oven heater is not coming
in contact with the oven shell or other
nearby components.
Faulty main PCB. Replace main PCB.
Oven temperature will not go
to maximum. Fast oven but power is 208 V rather
than 240 V. Correct power wiring in lab.