Disassembly For Troubleshooting And Repair - HP 10811A Operating & Service Manual

With the cover and foam insulator removed to thermal fuse cannot
protect the oven circuit from thermal runaway. Caution should be
used at all times.

8-57. DISASSEMBLY FOR TROUBLESHOOTING AND REPAIR

8-58. Perform steps 1 through 3 for the 10811A oscillator and steps 4 and 5 for the 10811B oscillator.
Once these steps are completed, follow steps 6 through 10 for both oscillators.
8-59. For the 10811A Oscillator:
Step 1. Remove the three screws securing the bottom cover to the outer housing, and remove
bottom cover.
Step 2. Remove the two screws securing the pc edge connector to the outer housing.
Step 3. Remove the foam sheet to expose the oven controller circuit board.
If troubleshooting the oven controller, stop here and go to
trouble is in the oscillator circuit.
For the 10811B oscillator:
Step 4. Remove the four screws securing the cover to the outer housing.
Step 5. Disconnect the flexible circuit attached to the cover from the 7-pin connector mounted to
the oven controller circuit board.
If troubleshooting the oven controller, stop here and go to
is in the oscillator circuit.
The following steps will be performed for both oscillators.
Step 6. Using a long, small diameter tool, remove the complete oscillator assembly by inserting
the tool into the tuning capacitor access hole (labeled FREQ. ADJUST) and pushing on the
capacitor until the circuit can be grasped and removed freely.
Do not remove the circuits by pulling on the edge connector or
flexible circuit. Damage to the flexible circuit may occur.
Step 7. Using a Pozidriv screwdriver
to the oven mass. Remove the washers and transistor insulators.
When reassembling the oven mass the heater transistor screws must
be tightened to a torque of 44 Newton meters (5 in.-Ibs.)
Step 8. Tilt the oven controller assembly back and remove the foam insulator between the oven
controller assembly and the oven mass. Be careful not to break the two black thermistor wires
attached to the oven controller assembly.
Step 9. Remove the eight screws (four each side) securing the covers to the oven mass
assembly.
Step 10. Use two of the screws from each cover (removed in Step 9) to secure the boards to the
mass for troubleshooting.
CAUTION
paragraph
paragraph
CAUTION
10811A Only
, remove the two screws securing the heater transistors
NOTE
Model 10811A/B
8-69. Go to Step 6 only if the
8-69. Continue only if the trouble
51