SCP SCIENCE DigiPREP, Service Manual

Page: 78 / 88

SCP SCIENCE
78
KeyPad
Version 1.0
1. Set your multi-meter to continuity.
2. Measure between pin 4 (ground) and the
graphite block. This should return continuity.
Ensure you measure in a location that is not
covered with Tefl on coating.
3. Measure between pin 4 (Ground) and each pin
individually. No continuity should be detected
between them.
4. Measure between pin 1 (EX+) on the umbilical
cord and pin 1 of the dongle port. This should
return continuity.
5. Measure between pin 7 (EX-) on the umbilical
cord and pin 3 of the dongle port. This should
return continuity.
6. Measure between pin 6 (M+) on the umbilical
cord and pin 2 of the dongle port. This should
return continuity.
7. Measure between pin 5 (M-) on the umbilical
cord and pin 4 of the dongle port. This should
return continuity.
8. Measure between pin 2 (N) and 3 (L) on the
umbilical cord. This should return a resistance
based on the table on page 85.
INTERNAL RTD, C176
The internal RTD is a variable resistor whose
value changes as a function of temperature. By
determining the change in resistance, the
controller’s programming is able to determine the
temperature of the block to a very accurate degree
(within 0.1 degrees).
At room temperature, 21 degrees Celsius, the
internal RTD (C178) returns a value of approximately
108 ohms.
To measure the value of the internal RTD, insert
the 4-pin
Digi
PREP
dongle into the block’s port.
For new models, measure between pin 1 and pin
4 of the umbilical cord. For older models, measure
between pin 6 and pin 5 of the umbilical cord.
If you cannot read a resistance, visually inspect the
wires running from the
Digi
PREP
dongle port to the
RTD, as well as the wires from the port to the umbili-
cal cord.
To determine which style of umbilical
cord you have, please review the
schematics and serial numbers listed
on pages 80 and 81.
HEATING PAD TESTING PROCEDURES
The main methods for testing heater pads for
malfunctions are through resistance checks and
visual inspections.
To measure the resistance of the heater: for new
umbilical cord models, measure between pin 7
and pin 9. For old umbilical cord models, measure
between pin 2 and pin 3.
To determine which style of umbilical
cord you have, please review the
schematics and serial numbers
depicted on pages 80 and 81.
The following table displays the resistance values
of functioning heaters:
MODEL
VOLTAGE SELECTOR
SWITCH POSITION
RESISTANCE
Digi
PREP Jr
115V
230V 18

± 2

71

± 2

Digi
PREP MS
115V
230V 15

± 2

57

± 2

Digi
PREP HP
115V
230V 15

± 2

57

± 2

Digi
PREP LS
230V 20

± 2

Digi
PREP HT
230V 16

± 2

Resistance of the mat will change
depending on the voltage setting.
NOTE
NOTE
NOTE