User`s guide

3-18 Chapter3
Theory of Operation and Troubleshooting
Troubleshooting
3. The blue wire is the solenoid drive for pin number one. The voltage on
this pin measures approximately +0.62 Vdc.
4. The green wire is the solenoid for pin number two. The voltage on this
pin measures approximately +16.3 Vdc.
5. Measure the solenoid voltages.
NOTE Voltages may vary depending on the test Port state of the instrument.
a. Press Seq, TTL I/O, TTL OUT, TESTSET I/O REV, 6, x1, I/O REV, 7, x1.
b. Toggle between 6, x1 and 7, x1 while measuring bias pins 1 and 2
on S3.
The voltage on bias pins 1 and 2 should alternate between
+0.62 Vdc and +16.3 Vdc when the instrument is toggled from 6, x1
to 7, x1. If the bias voltage changes state but there is still no RF at
Port 1, the transfer switch S3 (see Figure 3-13) may need to be
replaced. If the bias voltage remains the same, check the LEDs to
make sure the source test port is being redirected.
When the instrument is toggled from Port 3 to Port 1 and Port 3 to
Port 2, the bright LED should remain on Port 3. If the LEDs are
working on Port 3 to Port 1, and the bias voltage is still incorrect
on switch S3, disconnect the J4 connector (see Figure 3-17) and
check the bias voltage on S4 (+0.62 Vdc and +16.3 Vdc). Toggle
between the TESTSET I/O REV, 6, x1 and TESTSET I/O REV, 7, x1
states. If the bias voltage does not change, replace the test set
interface board. If the bias voltage does change, replace S3.
If the A channel response is degraded and a bad load match exists
on Port 1, this may indicate a bad test port coupler. To check the
load match on Port 1, follow the instructions on the verification
procedure in this service guide. Replace the Port 1 coupler if the
Port 1 load match fails.