HP 8562E, Service Manual

Page: 430 / 482

Table 12-2. TAM Tests versus Test Connectors
Connector Manual Probe Troubleshooting Test Measured Signal Lines
YTF Offset DAC
MS6
YTF Gain and Offset Input MS2
YTF Gain DAC MS1
YTF Drive
MS3
Band Switch Driver MS8
Main Coil Coarse DAC
MS3
L O D A D r i v e
MS5, MS6, MS7, MS8
Second Conv PIN Switch
MS8
Second Conv Mixer Bias MS1
Second Conv Drain Bias
MS3
Second Conv Doubler Bias MS4
Second Conv Driver Bias
MS5
First Mixer Drive Switch
MS7
First Mixer Drive DAC MS6
R e v i s i o n
MS7
IF AMP/Limiter Bias
MS6
Third LO Tune Voltage
MS3
3rd LO Driver Amp MS8
SIG ID Collector Bias MS7
RF Gain Control Test
MS3
R e v i s i o n MS3
External Mixer Switch
MS8
Signal ID Switch MS5, MS6
External Mixer Bias MS7
Low Band Problems
1. Disconnect
all inputs from the front-panel INPUT connector.
2. Set the HP 85623 to the following settings:
Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 Hz
Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input attenuator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0
3. The LO feedthrough amplitude observed on the display should be between -6 and
- 3 0
The marker will not PEAK SEARCH on the LO Feedthrough when in a
non-zero span. To measure the LO Feedthrough amplitude with the markers,
set the SPAN to 0 Hz and CENTER to 0 Hz. Press ON.
4. If the LO feedthrough amplitude is within limits, but signals are low, the RF path
following the A8 mixer is probably operating properly.
12-4 RF Section