2 maintenance and servicing – Metrohm 750 Autosampler User Manual
Page 44
4.2 Maintenance and servicing
750 Autosampler
41
4.2
Maintenance and servicing
4.2.1
General information
The 750 Autosampler was designed for years of maintenance-free use.
The X,Y,Z sample tray assembly is equipped with bushings and bear-
ings made from materials chosen to minimize the need for lubrication.
The needle drive carriage position is recalibrated at powerup and with
the start of each method. Therefore, there are no user serviceable parts
in the X,Y,Z sample tray assembly or the needle drive carriage with the
exception of changing the transfer needle (see section 4.2.2).
4.2.2
Transfer needle replacement
If the transfer needle is blocked it must be replaced. Proceed as follows
(see Fig. 11):
1
Prepare Autosampler
•
Stop any method which may be running by pressing
•
Park the transfer needle 55 by pressing
Park
Needle
".
•
Switch off instrument by means of mains switch 13
13.
2
Remove old needle
•
Hold connection screw 21
21 with open-end spanner and un-
screw needle holder 17
17 together with transfer needle 55 with
open-end
7
/
32
"
spanner (6.2621.020).
•
Use two open-end spanners to unscrew nut 19
19 from connec-
tion screw 21
21 and remove connection screw 21
21 from holder
20
20.
•
Remove old transfer needle 55 from needle holder 17
17.
3
Insert new needle
•
Insert 6.2620.130 spare needle with already mounted ferrule
16
16 in needle holder 17
17.
•
Insert connection screw 21
21 into holder 20
20 from below.
•
Use an open-end spanner to screw nut 19
19 firmly onto con-
nection screw 21
21.
•
Screw needle holder 17
17 onto connection screw 21
21 by hand.
•
Hold connecting screw 21
21 with open-end
7
/
16
"
spanner,
tighten up needle holder 17
17 with open-end
7
/
32
"
spanner
(6.2621.020) by about half a turn.