Barnstead International Thermolyne 859 Series, Service Manual

Page: 102 / 118

102
a) Each nut is physically located 1/2” to 1”
directly behind the hinges. These nuts secure
the control section to the front of the NCAT.
5) The control panel will slide out from the back
side of the NCAT (Approximately 2” out from the
unit.)
a) It is important not to pull the control section
too far back with force, as several wire harness-
es are still connected securing the control sec-
tion in the NCAT.
6) The solid-state relays are now visible, mounted
on the back wall, on the lower left side (a heat
sink device is mounted on the outside of the
NCAT). See photo on previous page.
a) The relay on the far left side is for the blower
motor (exhaust fan). This relay will have two
black wires connected to pins “1” and “2”; a yel-
low wire to pin “3”; and a green wire to pin “4”.
b) The relay in the middle is for the chamber
elements. This relay will have two white wires
connected to pins “1” and “2”; a red wire to pin
“3”; and a black wire to pin “4”.
c) The relay on the right side (near the center of
the furnace) is for the filter element (afterburn-
er). This relay will have two white wires con-
nected to pins “1” and “2”; an orange wire to pin
“3”; and a brown wire to pin “4”.
7) Connect the voltmeter leads to terminal pins
number 3 and 4 of the solid-state relay. CAU-
TION: You will also be measuring live voltage, a
potential shock hazard!
a) Each relay has 4 screw terminals, each
labeled “1”, “2”, “3”, “4”. Terminal pins “1” and
“2” on all three relays are considered the output
and will only have AC voltage across them at
various times of operation. Terminal pins “3”
and “4” on all three relays are considered the
input and will only have DC voltage across them
at various times of operation. Pin “3” is the DC
E
QUIPMENT
T
EST
P
ROCEDURE