SCP SCIENCE DigiPREP HP, Руководство по обслуживанию, Страница: 33 / 49

KeyPad service manual
Rev.1.1 33
6. A/D Converter
The analog to digital conversion is the feedback information coming from the
heater block temperature sensors or from a
Digi PROBE . The CPU section
handles this information in order to control the temperature of the heating block.
6.1 Possible A/D problem

If the Digi PROBE is reading wrong temperature, make sure that the
Digi PROBE itself is functional before looking at the converter circuit.
This can be accomplished by measuring the resistance across pin 1
and 2 of connector of the
Digi PROBE .
o
Typical 25

C = 108 ohms

If the display is printing “
Digi PROBE
error”, then the A/D can be faulty
but make sure that the section 8 has been verified before changing the
A/D.
6.1.1 RTD input connection

Visually inspect the external connection of the Digi PROBE .

Unscrew the bottom plate and make sure that the JP2 connector is
fully connected with the jumper (see figure 21 for location)
Figure 21: JP2 Connector location
Legend:
1. JP2 header
1