KeyPad
Version 1.0
SCP SCIENCE
23
FAILED KEYPAD BUTTONS
Please write down each failed
button number in order to see
if the problem is for a complete
row or column or if it is for
different row and column buttons
• In order to verify the buttons please reset the
KeyPad controller (ON/OFF) and select the
Operation section in the main menu.
•A target temperature is now asked.
•First, verify all Digits. Every time you press a
button, you should see the corresponding
number under the cursor.
• When it is done and all Digits are fi ne, enter 25.
and press the ENTER key.
•Enter "1" in the "Target Time" menu and
press the ENTER key.
•Now it is time to verify the ARROW keys.
• Press the left and right arrow key a couple
of times and see if the cursor switched
from ON to OFF and so on.
• Select HEATER OFF and press ENTER (make
sure DigiPREP is connected).
•Enter a time scale of 1 minute and press enter.
• Press the ALARM, TARGET TEMPERATURE and
TARGET TIME button one at a time and verify
if they execute correctly the commands below:
ALARM
A small "AL" should appear on the
LCD display.
TARGET TEMPERATURE
The target temperature menu should
appear.
TARGET TIME
The target time menu should appear.
KEYPAD DIAGNOSTIC SECTION
To identify if the trouble is caused due to the
keypad buttons or a faulty circuit, verify the
impedance of the buttons that do not respond to the
commands by measuring between the following pins
of J8 (see fi gure 9):
Pin 1 and pin 5 .............. Button #3
Pin 1 and pin 6 .............. Alarm Button
Pin 1 and pin 7 .............. Button #2
Pin 1 and pin 8 .............. Button #1
Pin 2 and pin 5 .............. Button #6
Pin 2 and pin 6 .............. Temperature setting button
Pin 2 and pin 7 .............. Button #5
Pin 2 and pin 8 .............. Button #4
Pin 3 and pin 5 .............. Button #9
Pin 3 and pin 6 .............. Time setting button
Pin 3 and pin 7 .............. Button #8
Pin 3 and pin 8 .............. Button #7
Pin 4 and pin 5 .............. Right shift button (>)
Pin 4 and pin 6 .............. ENTER button
Pin 4 and pin 7 .............. Button #0
Pin 4 and pin 8 .............. Left shift button (<)
If the buttons are OK:
•Pushed : Less than 200 ohms.
•Not pushed: less than 30 Mohms.
If all the values are correct, the circuit is faulty.
Change the KeyPad PCB.
FIGURE 9 : PUsH BUTTON MEASURING LOCATION
Legend
1. J8 (pins 1 to 8)
NOTE
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