CMU MODULE Replacement
1100.4903.82 3.37 E-4
Replacing the RF FRONTEND
(see chapter 5, spare part list, Current No. 520 and explosion drawing 1100.0008.01 D sheet 2)
The RF FRONTEND is installed at the bottom of the CMU at the front right. For replacement proceed as
follows:
Opening the instrument and removing the RF FRONTEND
½ Switch off the instrument, pull the mains plug and unscrew the rear-panel feet.
½ Place the instrument onto the front carrying handles, push the tube upwards and take off.
½ Place the instrument upside down to make the bottom accessible.
½ Pull off the ribbon cable to the MOTHERBOARD on the RF FRONTEND. Completely unscrew RF
SMA coax cables to the RXTX BOARD1 (if present, also those to the RXTX2 BOARD and
RXTXAUX1/2 connectors) on the RF FRONTEND and RXTX BOARD1 using a special wrench
∗
.
½ Unscrew the two countersunk screws at the bottom front of the front frame and one countersunk
screw on the side panel of the CMU for supporting the RF FRONTEND.
½ Pull the RF FRONTEND approx. 20 mm towards the rear and then swing towards the bottom.
Installing the new RF FRONTEND MODULE and completing the instrument
½ Insert the RF FRONTEND into the instrument in the reverse order and connect all cables.
½ Complete the instrument without causing damage to the cables.
½ Connect the instrument to the mains and switch on.
Automatic module data adjustment
½ During startup observe the display.
½ When three BEEPs can be heard, press the MENU SELECT key.
The version manager is started (see also chapter 4, Firmware update). The display includes the
menu item FIRMWARE UPDATE AFTER BOARD CHANGE.
½ Press the softkey to the left of the above mentioned menu item.
The automatic module data adjustment is performed under software control, firmware updates for
microprocessors and programmable devices being performed as well. This may take a few minutes.
After the adjustment has been terminated, the operating software starts automatically and the CMU is
ready for use and complies with the specifications, except for the level accuracy.
In order to achieve the level accuracy described in the data sheet, a so-called path error data record is
necessary.
To this end, the CMU must be measured using the test system ACS 100 (see chapter 1, Performance
Test).
∗
available in CMU-Service Kit CMU-Z3 (1100.7690.02)
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