Pg 3.14 H22
As mentioned, beside each input and output terminal there is a bank of red LEDs. Each light corresponds to
its input or output. An input LED will light when it's specific input signal is being received at the PLC and output
LED's will light when the PLC commands specific outputs. If an output LED is on but the output does not happen,
check for voltage at the specific output wire. If voltage is not present then either the output relay is faulty/stuck
or the output (3 amp) fuse has blown. (See fuse information below) If a fuse is blown, a shorted directional
valve coil (good coil should measure 30 to 40 ohms), shorted noise suppresser at the coil, or shorted wiring
could be the cause.
If the fuse is good and no output voltage condition still exists, with the output light on, then the relay is
defective.
If this is the case the PLC will have to be returned to the manufacturer for repair. (Contact HYD-MECH
SAWS).
FUSES: The PLC has five glass fuses in line with it.
Fuse 'F1' is a 2 amp instant blow fuse which feeds power to the input side of the PLC through input
terminal 'L'.
Fuses 'F2' to 'F5' are 3 amp time delay fuses which each supply power to a specific bank of output
relays through that bank of relay's 'COM' terminal:
F2 is wired to terminal 'COM 1' supplying Outputs - Y0, Y1, Y2, Y3
F3 to terminal 'COM 2' supplying Outputs - Y4, Y5, Y6, Y7
F4 to terminal 'COM 3' supplying Outputs - Y10, Y11, Y12, Y14
F5 to terminal 'COM 4' supplying Outputs - Y14, Y15, Y16, Y17
PROBLEM # 4, No Display.
POSSIBLE CAUSES;
i) No power to the PLC.
ii) PLC unit failure.
iii) Faulty connection of cable between PLC & Interface
DIAGNOSIS;
i) Check POWER LED (see page 3.17 - Status lights) - to be on when the PLC is switched on.
If the light is on, PLC may have failed. Check for proper connection of cable at PLC & at
interface. If connection is secure replace. If light is not on - check the (2 amp) PLC fuse.
If the fuse is OK, check power to it.
PROBLEM # 5, No Blade Speed Display.
POSSIBLE CAUSES;
i) Fault at proximity sender - bad sender, misadjusted sender (gap should be approx. 0.015")
- contamination on the end of the sender
ii) Fault at the PLC - bad connection of sender wiring
- faulty PLC input
DIAGNOSIS;
i) Check for LED light on the sender - light on indicates prox. sender power connections are correct
and sender is activated. Problem could be with the sender, signal wire to the PLC or with the PLC. With blade
running, proximity LED should pulse. Likewise, the PLC input LED (X2) should be pulsing. If both LED's are
pulsing with the blade running, the PLC is the problem. If the sender LED is pulsing but the input (X2) LED is not;
there is a problem between the sender and the PLC input (X2) terminal.
- If the LED on the sender is not on, the problem is with the sender wiring or the sender is at fault.
To Next Page
