TM 5-3610-253-14
MOTHERBOARD (ST and SZ) FUSES
Fuse Designation
Use
*Voltage/Amperage
The two parts of the motherboard are identified as the standard control PC card ST
and the additional control PC card SZ. The other PC cards are plugged into pins on
these two cards. Additional control PC card SZ contains relay d5, for safety bolt
solenoid, monitor relay d38, for the light barrier, and components for optional
equipment. When optional equipment is not present, the control circuits are not
used.
(2) Backgauge brake control PC card 27. Controls the backgauge brake.
When contractors controlling power to the backgauge motor and backgauge forward con-
trols are closed, a 50 F capacitor on PC card 27 is loaded with 220 V ac via a
diode. The capacitor supplies its energy to brake solenoid coil m19 via a thyristor
stage. The high voltage provides quick engagement of the brake. When the capacitor
discharges, the capacitor voltage locks the thyristor stage and the brake is held by
just 25 volts via the diodes.
(3) Light barrier PC card 9.rovides control, power and testing for the
P
light barrier. When the low voltage from the photocells in the light barrier is
received, it causes a transistor stage on the card to become conductive toward a 0-
logic voltage level. Relay d37 is energized, which switches on the signal lamp to
indicate there is no fault condition. Each time the cutting buttons (b28a and b28b)
are activated, signaling a cut, card 9 starts an automatic test of the light
barrier. A O-signal is laid across the transistor stages from transistor stage 38.
On the light barrier photo element plate, the voltage will rise for a short period
to at least 0.5V. Relay d37 de-energizes and the signal lamp is shut off momen-
tarily. If relay d37 will not de-energize during the test, the cut is locked via
transistor stage 9 R1 on PC card 9.
(4) Safety bolt control PC card 7SB.
Controls operation of the safety bolt.
(5) Conical (clamp) valve control PC card 5. Controls operation of clamping
solenoid in hydraulic system control block. Control of unit depends on the opera-
tion being performed.
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