Practical Performance; Electronic Exchange - Siemens Sitrans P DS III PA Serie Servicehandbuch

Practical performance

3.1

Electronic exchange

he following description shows how you can change the electronics 7MF49971DK or
7MF 4997 1DL in the connection room of the transmitter:
1. Turn off voltage for the device.
2. Remove the cover (1, Figure 4, page 56 and Figure 5, page 56) and the digital
display (2, Figure 4, page 56 and Figure 5, page 56) behind it. In addition to this
you remove both screws and then you can take away the conductor band (Figure
7, page 57).
3. Unscrew the two threaded bolts (4, Figure 4, page 56 and Figure 5, page 56)
holding the electronics (4, Figure 4, page 56 and Figure 5, page 56) in place.
4. Remove the cast electronic block carefully from the housing (Figure 9, page 57
and Figure 10, page 58). Attention: the conductor band of the measuring cell and
the conductor band (ribbon cable) for the keypad that is available with product
release 30 and higher must not be pulled taught. The keypad cable is soldered
in a permanent connection with the electronics.
5. The following applies for the compact electronic block (only one conductor band):
Pull of the measuring cell board (6, FFigure 4, page 56 and Figure 5, page 56)
which connects the measuring cell (10, Figure 4, page 56 and Figure 5, page 56)
to the electronics with the correct tool e.g. a pair of tweezers (Figure 13, page 58
and Figure 15, page 59) and plug it to the new electronics (Figure 16, page 59);
The conductor band must not be stretched too tight (Figure 12, page 58). Make
sure the conductor band is not crushed in order to avoid short circuits.
6. The following applies for the electronic block with a separate conductor band for
the keypad connection (as of product release 30): Carefully remove the measu-
ring cell board that connects the measuring cell with the electronics (Figure 14,
page 59). Unscrew the keypad circuit board from the bottom of the housing and
remove it (Figure 17, page 59). Position the keypad circuit board for the new
electronics onto the threaded bolts on the bottom of the housing and screw them
in snuggly. Attention: If the electronics have been supplied with two conductor
bands the first time then, by inserting and tightening the screws that have been
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