Metrohm 757 VA Computrace - Manual (Page 20)

3 Installation
757 VA Computrace – Hardware
16
3.2.4 Equipping the measuring head
The fixtures inserted in the openings and connections of the measuring head 20 in
the 757 VA Computrace Stand depend on the working electrode selected (MME or
DME) (see Fig. 6). The fully equipped measuring head for operation with a multi-
mode electrode is illustrated in section 2 (Figs 3 and 4), that for operation with a ro-
tating disk electrode in section 3.4 (Fig. 12).
When equipping the measuring head for the first time, the best procedure is as fol-
lows:
1 Preparations
• Prepare multi-mode electrode MME 17 (details, see section 3.3) or rotat-
ing disk electrode RDE (details, see section 3.4) for operation.
• Prepare reference electrode 22 (details, see section 3.5) for operation.
• Tilt back cover 1 of measuring head arm.
2 Insert dummy stoppers
• Screw dummy stopper 41 (6.1446.040) into opening 52.
• Screw dummy stopper 40 (6.1446.040) into opening 53.
3 Insert 4-way microtip (option)
The 6.1824.000 4-way microtip has to be installed if 765 Dosimats are used
for automatic solution addition. Proceed as follows:
• Remove stopper from nipple 23 and insert 4-way microtip 26 into nipple
23 as far as it will go.
• Tighten nipple 23 using a 6.2739.010 Wrench until the 4-way microtip 26
can no longer move.
• Pull the 4 lengths of PTFE tubing of the 4-way microtip 26 in succession
from above through the opening 65 (connection of 665 or 765 Dosimat,
see section 3.8).
4 Install stirrer or RDE
in operation with MME:
• Screw stirrer tip 42 to drive shaft 24 (see also section 3.7).
• Insert stirrer in opening 60 as far as it will go.
• Stretch drive belt 28 (6.1244.020) between drive wheel 31 and drive shaft
24 of the stirrer.
in operation with RDE (option):
• Screw electrode tip 99 (6.1204.XXX) to drive shaft 100 (6.1246.000)
(see also section 3.4).
• Insert RDE in opening 60 as far as it will go.
• Stretch drive belt 28 (6.1244.020) between drive wheel 31 and drive shaft
100 of the RDE.
• Attach electrode cable 16 (WE) to the RDE: push cable lug under the
screw and then tighten screw firmly.