Rohde & Schwarz 1164.4391.03, Service Manual

Page: 169 / 254

R&S FSP Module Replacement
1164.4556.82 3.65 E-1
Replacing the Electronic Attenuator A50 (Option R&S FSP-B25)
(See chapter 5, spare parts list, item 1400, and drawings 1164.4391 and 1129.7800.)
The electronic attenuator is fitted behind the RF attenuator under the fan.
Opening the Instrument and Removing the Electronic Attenuator
Switch off the instrument, pull the mains plug, unscrew the 4 rear-panel feet (450) and push the tube
(410) backwards and take off.
Place the instrument on the left side frame and loosen RF cable W28 (1430/1440) at the electronic
Attenuator output 1400).
Unscrew 4 countersunk screws (1460) at the right frame.
Note : The electronic attenuator will only be fixed with the RF cables at the front.
Fix the electronic attenuator and disconnect RF cable W29 (1420) at the output of the attenuator
(20).
Move carefully out the RF attenuator and disconnect the ribbon cable at the electronic attenuator.
Installing the New Electronic Attenuator
Connect (only loose) cable W29 (1420) at the new electronic attenuator.
Note: Label X3 shows to the electronic attenuator.
Connect the ribbon cable (W50) at the new attenuator.
Move the new electronic attenuator in the instrument and connect cable W29 (1420) to the output of
the attenuator (20).
Screw the four screws with washers (1460) at the right frame in the electronic attenuator.
Fix the RF cable (1420) at the output of the attenuator (20) and the electronic attenuator.
3 GHz Model (1164.4391.03)
Connect cable W28 (1430) between electronic attenuator and the frontend (100) .
7 GHz Model (1164.4391)
Connect cable W28 (1440) between electronic attenuator and the MW converter (130).
Completing the Instrument
Push the tube (410) on the instrument and mount the 4 rear-panel feet (450).
A cold boot is necessary after replacing the attenuator.
See section "Performing a Cold Boot" in this chapter.
Connect the instrument to the mains, switch on the instrument power switch and switch on the
instrument with the ON/STANDBY key
After starting the instrument check for system messages:
- [ SETUP : SYSTEM INFO : SYSTEM MESSAGES ]
Start selftest and check results:
- [ SETUP : SERVICE : SELFTEST ], then [SELFTEST RESULT]
Start a total calibration and check the result:
- [ CAL : CAL TOTAL ] , then [ CAL RESULTS ]
Create a backup of the EEPROM data (see chapter 2, section "Adjustment of Module Data").
Check frequency response with chapter 1 and make a correction if necessary.