Barnstead International Thermolyne 859 Series, Service Manual

Page: 104 / 118

104
solid-state relay is working properly. Taking voltage
measurements at this point is not necessary.
However, if the blower motor does not run or is run-
ning while the NCAT is in the preheat mode, the
solid-state relay may be defective. Take voltage
measurements as described in step 11 to determine
if the solid-state relay is defective.
Keypad
A) Keypad
Equipment needed:
- Phillips screw driver
- Jumper wires or needle nose pliers
1) Disconnect the NCAT unit from the power source.
2) Lower the control panel by removing the 4 screws
along the top edge. Control panel hinges down-
ward.
3) Locate and disconnect keypad from J2 terminal of
display board.
4) Reconnect the NCAT to the power source.
5) Use jumper wires or needle nose pliers to short two
pins together on the J2 display board to simulate
pressing a key. (Use the matrix chart below to iden-
tify what to pins to short out to simulate a key-
stroke.)
a) The J2 terminal is an 8 pin electrical connection
point. Connection terminal is orientated such that
pin 1 is nearest D7 and pin 8 is nearest the J1 con-
nection terminal.
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QUIPMENT
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EST
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ROCEDURE