2009 by ELTRA GmbH Germany – July 2009 – Service Manual Thermostep
Page 54
n.)
Carefully lift out balance pedestal (see Fig. 3.18).
o.)
Rotate carousel shaft to expose two of the four 2.5mm allen screws securing the
carousel shaft. Loosen the screws. Continue to rotate the shaft to expose the
remaining 2 x 2.5mm screws. Loosen these screws and then lift out the carousel
shaft (see Fig. 1.2).
p.)
Disconnect the furnace wires from the two electrical terminals (5mm allen screws)
at the rear side of the instrument.
q.)
Loosen the 5mm allen screw on the s/s strap around the furnace and carefully lift
off, avoiding the electrical wires at the rear of the furnace.
r.)
Loosen the 2 x 2.5mm allen screws securing each of the front two positioning
supports and slide them forward to free the furnace.
s.)
Lift out lower furnace assembly.
3.15 Replace the Lower Furnace in the Thermostep TGA
Unplug instrument from electrical supply and disconnect the compressed air supply.
Assuming the lid is in the propped up position.
a.)
Lower new lower furnace into the TGA frame and slide it backwards to rest
against the rear positioning supports.
b.)
Align the centre shaft hole and the balance pedestal hole the balance spigot and
centre drive shaft and ensure that the furnace is centralized.
c.)
Place the s/s furnace strap back into the frame and check the height of the furnace.
The lower lip of the furnace should be at the same height as the s/s surround. There
are three height adjustable furnace supports under the furnace that can be adjusted
to achieve this important stage.
d.)
Check also, once the furnace is at the correct height and aligned that there is an
even 4mm gap between the s/s surround and the furnace.
e.)
Once the furnace is aligned correctly slide the the two front positioning support
towards the furnace and tighten the 2 x 2.5 mm allen screws.
f.)
Place the s/s strap over the lower furnace and position the adjustable clamp screw
mechanism adjacent to the RHS front positioning support. Tighten the 5mm allen
screw to secure the furnace in position.
Recheck alignment.
g.)
Connect the furnace and supply cables to the terminal posts at the rear of the
furnace. Ensure that the wires from the furnace are pushed down so that there is no
possibility of them coming into contact with any metal surround or frame above or
below. Also ensure that the supply cables are clear of the hot surfaces of the
furnace and cannot be trapped in the lid mechanism.
h.)
Replace and secure s/s surround with 6 x 2.5mm csk allen screws.
i.)
Lower carousel shaft into the centre hole. Place carousel on to the four support
pins in the shaft. Position the carousel so that the first slit in the carousel to the left
of one of the support pins is directly above and central over the balance pedestal
hole.
j.)
With carousel in this position rotate the motor drive to expose two of the four shaft
securing screws located below the furnace. Tighten these screws. Rotate the
carousel to expose the other two securing screws and tighten.
k.)
Now rotate the carousel so that the home sensor screw in aluminum wheel is
directly opposite the home sensor. Check the carousel is now aligned with the slot
on the RHS of any one of the support pins. This will be the home position and
