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RAP 2.46 Knife Down Switches
Input 10
There are two knife down switches, each com-
prised of a steel collar and an isolated stop block
(Figure 2-70). When the cutting mechanism
reaches the bottom of its stroke, each stop block
comes in contact with its corresponding collar,
thereby acting as a closed switch. The DI/HS
PWB (Figure 2-71) senses when both switches
are closed, then sends a signal to the main PWB
indicating that the cutting mechanism is down
and should return up.
Possible Fault Indicators
"Knife failed to reach down
limit in time" message is displayed.
Initial Actions
Make sure the knife depth adjustment is not set
too deep, causing the knife to bottom out in the
cut stick and stall before contact can be made at
the switches (ADJ 4.3 Knife Depth Adjustment).
If a newly re-sharpened knife has just been in-
stalled, make sure the knife has not been sharp-
ened below the minimum blade height (see
"Knife Sharpening Amount" in REP 4.2 Knife Re-
placement).
Perform ADJ 4.15 Knife Cushion Adjustment.
Remove any debris that may be interfering with
the stop blocks from making contact with the col-
lars.
Check and repair loose or damaged wires 3 and
4 from the stop blocks to the electrical panel.
Check and repair loose or damaged wire 46 at
the electrical panel.
The following procedure must be performed with
the knife up.
2. Status Indicator RAPs
Procedure
1. Switch the main power ON and go to the di-
agnostic screen (GP 6.2 Input/Output Diag-
nostics). Does the diagnostic screen show
input "Knife Down" off?
Y
N
Disconnect wire 46. On the diagnostic
screen does input "Knife Down" switch off?
Y
N
Disconnect power and replace the con-
sole PWB (REP 4.24 Console PWB Re-
placement).
Check continuity between wire 3 at the
DI/HS PWB and machine ground, and also
between wire 4 and machine ground. Do
both of these measure open (no continuity)?
Y
N
One or both stop blocks, wire 3, and/or
wire 4 are making contact with machine
ground. Locate and repair the short(s).
Disconnect power and replace the DI/HS
PWB (REP 4.25 DI/HS PWB Replacement).
2. Short wire 46 to 74. On the diagnostic
screen does input "Knife Down" switch on?
Y
N
Disconnect power and replace the console
PWB (REP 4.24 Console PWB Replace-
ment).
3. Remove short. Is there 9 VAC between wire
11 at the DI/HS PWB and machine ground?
Y
N
Go to RAP 2.5 DC Power.
4. Short wires 3 and 4 at the DI/HS PWB to
machine ground. On the diagnostic screen
does input "Knife Down" switch on?
MAY 2019
2-54
Y
N
Disconnect power and replace the DI/HS
PWB (REP 4.25 DI/HS PWB Replacement).
5. Remove the shorts from step 4, then short
both of the stop blocks to their correspond-
ing collars. On the diagnostic screen does
input "Knife Down" switch on?
Y
N
Repair wires 3 and/or 4.
6. Go to ADJ 4.7 Knife Down Switches Adjust-
ment.
Figure 2-70. Knife Down Switches
Figure 2-71. DI/HS PWB
CMT-130TC Book Trimmer
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