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THE OSCILLATOR'S INTERNAL OVEN MASS TEMPERATURE MAY
BE AS HIGH AS 85°C (185°F). TO AVOID SERIOUS BURNS DO NOT
REMOVE OSCILLATOR CIRCUITS AND/OR OVEN MASS ASSEMBLY
FROM
SUFFICIENTLY COOLED (APPROXIMATELY ONE HOUR WITH
BOTTOM COVER AND FOAM INSULATOR REMOVED). THE OUTER
HOUSING TEMPERATURE IS NOT A RELIABLE INDICATION OF THE
INTERNAL TEMPERATURE.
8-49.
The troubleshooting is arranged to allow the technician to quickly find the defective component(s)
without unnecessary removal of components.
8-50. TROUBLESHOOTING
8-51.
Failures in the 10811A/B can be divided into two sections:
1. Failure of the oscillator's circuits.
2. Failure in the oven controller circuits.
8-52.
Failures in the oscillator circuits can be divided into the following problems:
1. No output.
2. Output amplitude is too low or high.
3. Output is distorted (contains excessive harmonics).
4. Output is off frequency (high or low).
5. Output has excessive noise or frequency stability does not meet specifications.
8-53.
Poor frequency stability can be difficult to troubleshoot, and many times the oscillator is not at
fault. Environmental conditions can affect stability and should be ruled out first.
8-54.
Failures in the oven circuitry can be divided into the following problems:
1. No oven current (heat).
2. Excessive oven current (>600 mA).
3. Oven does not cut back after warm-up (this will open the thermal fuse if allowed to continue).
4. Oven does not regulate at the proper temperature. (This can be the cause for poor frequency
stability).
8-55.
Since the main oscillator and oven control power supply inputs are separate from each other, the
defective circuit can be operated without applying power to the complete oscillator.
8-56.
Determine which section is defective (oven or oscillator circuit), then proceed as described in the
following troubleshooting section. The two circuits can be investigated separately.
1. Remove top cover and insulator described in:
a. 10811A
b. 10811B
50
WARNING
THE
OUTER
CAN
paragraphs
8-59.
paragraphs
8-59, step 4.
UNTIL
THE
OSCILLATOR
Model 10811A/B
HAS
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Table of Contents
Troubleshooting
