Types Of Failures - HP 5334B Service Manual

i.
Twist together one of the two wires connected to pin 15 and the wire connected to pin 14. These are
the oven controller power supply inputs.
j.
Twist together the remaining wire connected to pin 15 and the wire connected to pin
1 1 .
This is the
oven monitor output.
k. Twist together the two wires connected to pins 2 and 3. These are the oscillator supply inputs.
1. Connect one banana plug to the free end of each wire.
m. Label each banana plug as follows:
Wire connected to:
pin 2
pin 3
Label
as:
oscillator supply (
-
)
oscillator supply (+)
pin 11 oven monitor (
+
)
pin 14 oven supply (
+
)
pin 15 (two wires)
oven monitor (
-
)
n. Inspect the connector for poor solder joints, bent, or damaged pins. Double check the labeling of the
plugs to be sure the polarity markings are correct. If the voltages are connected the wrong way,
damage to the oven oscillator may occur.
8-390.
Types of Failures
8-391. Failures in the oscillator unit can be divided into two sections:
a. Failure of the oscillator's circuits.
b. Failure in the oven controller circuits.
8-392. Failures in the oscillator circuits can be divided into the following problems:
a. No output.
b. Output amplitude is too low or too high.
c. Output frequency is too low or too high.
8-393. Poor frequency stability can be difficult to troubleshoot and many times the oscillator is not at fault. En-
vironmental conditions can affect stability and should be ruled out first.
8-394. Failures in the oven circuitry can be divided into the following problems:
a. No oven current (heat).
b. Excessive oven current ( > 600 mA).
c. Oven does not cut back after warm-up (this will open the thermal fuse if allowed to continue).
8-395. Since the main oscillator and oven control power supply inputs are separate from each other, the defec-
tive circuit can be operated without applying power to the complete oscillator.
8-3%. Determine which section is defective (oven or oscillator circuit), then proceed as described in the follow-
ing troubleshooting section. The two circuits can be investigated separately.
HP
5334B
-
Service Manual
8-57