Keypad Malfunction; Failed Keypad Buttons - SCP SCIENCE DigiPREP Series Service Manual

3. KeyPad Malfunction

The KeyPad is made of 16 independent switches. The information of a pressed
button is sent to the CPU with help of a row and column detector. One should
feel a 'click' upon pressing a button. If there is no click then the PCB board
adjustment should be checked.
4.7K
R11 R12
COL1
Alarm
Temp
Time
Enter

3.1 Failed KeyPad Buttons

NOTE: Please write down each failed button number in order to see if the
problem is for a complete row or column.

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 fine, enter 25.0 and press the ENTER key.

Enter "1" in the "Target Time" menu and press ENTER key.

Now its time to verify the ARROW keys.
KeyPad service manual
Rev.1.1
+5V
4.7K
4.7K
R13 R14
COL2 COL3
3 2
6 5
9 8
0
Shif t R
Figure 9: KeyPad electronic diagram
4.7K
COL4
R16
1
4.7K
4 R18
4.7K
R19
7
4.7K
Shif t L R20
4.7K
ROW4
ROW3
ROW2
ROW1
20