HP 85027A/B/C Service
Table 8-1. Conductors in Power Cable Wi
Connector Pin
Conductor (Label)
Signal
I
2
3
4
5
White (W)
Green (0)
Yellow (Y)
Blue (B)
Red(R)
Output
Return
Control
-12.6v
+15v
Power Cable Replacemnent
1.
To replace the power cable (WI), first open the bridge by following the
instructions above in “Gaining Internal Access”.
2.
Unsolder the wires connected to the power cable/circuit board assembly.
3.
Remove the two screws
from
the cable cover end plate.
4.
Remove the 1/2 inch hex nut which fastens the cable to the end plate.
5.
Replace the cable and reinstall it by performing in reverse order steps 1 through 4.
Note that the pads on which the wires are soldered are labeled as indicated in
Table 8-I.
Input Port and Test Port Resistance Checks
1.
Disconnect the HP 85027 from the analyzer. Momentarily ground the leads of the
DMM by touching them to its grounded chassis.
CAUTION
WORK STATIC-FREE. ESD can damage the highly sensitive
microcircuits in the HP 85027 bridges.
2.
Measure the resistance from the center contact of input port connector Ji to the
center contact of test port connector J2. The resistance should be 33±2ohms.
3.
Measure the resistance from the center contact of input connector Ji to signal
ground (the black/white wire connected to the microcircuit housing). The
resistance should be 83±2ohms.
4.
Measure the resistance from the center contact of test port connector J2 to signal
ground. It should be 83±2ohms.
5.
If any of the above results are not correct, the bridge microcircuit assembly Al is
defective and must be replaced: refer to “Al Bridge Microcircuit Assembly
Replacement.
Microcircuit Check
1.
Connect the input port of the bridge to the RF out port of the RF plug-in or
synthesized sweeper. Do not terminate the bridge test port.
8-3