HP 5890 SERIES II Service Manual page 194

Problem
1. One heated zone tempera-
ture runs away.
2. One heated zone will not
heat.
3. None of the heated zones
will heat, but the oven is
ok.
4. None of the heated zones
will heat, and the oven will
not heat.
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Heated Zone Troubleshooting
Probable Cause
a. Heater partially shorted to
chassis (grounded).
b. Faulty main PCB.
a. Heater partially shorted to
chassis (grounded).
b. Faulty main PCB.
a. Faulty F3 fuse on main
PCB.
b. Faulty main PCB.
a. Faulty main PCB.
SVC 6- 3
Corrective Action
1. Replace heater and sensor.
1. Replace main PCB (refer to
Section 9).
1. Replace heater and sensor.
1. Replace main PCB (refer to
Section 9).
1. Check main PCB fuse F3;
replace if required.
1. Replace main PCB (refer to
Section 9).
1. Replace main PCB (refer to
Section 9).