Barnstead International MIRAK 725 Series, Operation Manual And Parts List, Page: 24 / 36

24
M
AINTENANCE AND
S
ERVICING
Note
The set-up procedure should be fol-
lowed whenever the top plate assem-
bly or the logic board is replaced in
your MIRAK hot plate or stirring hot
plate. The set-up procedure is not nec-
essary when replacing the top plate or
the logic board in the stirrers.
Logic Printed Circuit Board
Set-up Procedure
1. Place a 500 ml flask with 300 ml of water on the top
plate. Place a standard laboratory thermometer (do
not use the probe for this procedure) 1/2" above the
bottom of the flask.
2. Turn the unit on and set the temperature at 70°C.
Allow the unit to operate at this temperature for five
hours.
3. At the end of five hours, note the temperature meas-
urement on the thermometer. (Ideally, the ther-
mometer should read between 41°C and 47°C.)
Subtract 44 degrees from the thermometer reading.
(If your thermometer reading is greater than 44°C,
your difference will be a negative number.) Record
6. Remove metal plate and then unscrew top plate
assembly.
7. Replace top plate assembly and reattach top plate
assembly to the case.
8. Replace metal plate, making sure thermocouple and
element wires come through metal plate. Then insert
screws and tighten.
9. Replace logic board and mount on bracket. Adjust
encoder wheel so that it freely rotates through slot
(optical pickup) on logic board. The black slot on the
logic board should project no further than the holes
in the outer perimeter of the encoder wheel.
10. Reconnect wires and cables to all three boards as
noted in step 2.
11. Proceed to Set-up Procedure.