204038
Rev. C, 01/17/12
© 2012, THE STANLEY WORKS. ALL RIGHTS RESERVED. 9 of 19
Table 2-3. Symptoms and Remedy
Symptom Remedy
Door set for CLOSED/LOCKED and door gets to closed position. Delayed
egress starts without pressing push bar. The dE indication is displayed on
MC521 OR MC521 Pro. The buzzer turns ON. K2 LED is OFF. K1 LED
is ON. And shear locks de-energize after 15/30 seconds.
Check connections from push bar
switches to two- contact transfer
contacts to quad transfer contacts to
K2 coil.
Door set for CLOSED/LOCKED in closed position. Shear locks energize,
but door panel can break out.
Adjustment is required on armature.
Set gap to between 0.080″ and 0.120″.
2.9.2 CHECK for correct DC voltage measurements on terminal block OR PC Board
assembly as follows:
a. SET the door to CLOSED/LOCKED.
b. CONNECT the negative (-) lead of the multimeter to TB2-10 of the controller.
c. Refer to Table 3-4, and CHECK each terminal number of the terminal block and
relay assembly for the voltage shown.
Table 2-4. TB2-10 Voltage Checks for DE-MC521 and MC521 Pro with Terminal Block OR PC Board
DE-
MC521
TB2
PC Board
Terminal
No.
Terminal
Block and
Relay Assy
Correct
Voltage
Possible Fault if Voltage is Incorrect
TB2-10 DE-TB1-1 1 24 - 28
VDC
The bridge on terminal block (not PC Board) 1-2 is loose.
The 24 VDC power supply disconnected.
TB2-10 DE-TB1-2 2 24-28
VDC
The 24 VDC power supply disconnected.
TB2-10 DE-TB1-3 3 24-28
VDC
The bridge on terminal block (not PC Board) 2-3 is loose. The 24
VDC power supply is disconnected.
TB2-10 DE-TB1-4 4 24-28
VDC
The 24 VDC power supply is disconnected. Fire alarm input is open
or missing.
TB2-10 DE-TB1-5 5 24-28
VDC
The bridge on terminal block (not PC Board) 4-5 is loose.
TB2-10 DE-TB1-6 6 24-28
VDC
MC521 was selected for fail safe, it should be fail secure.
TB2-10 DE-TB1-7 7 24-28
VDC
K1 is defective.
TB2-10 DE-TB1-8 8 NA Wire connection open from TB5-10. Check if MC521 is configured
for delayed egress.
TB2-10 DE-TB1-9 9 >20 VDC Push bar switch is open. Dual transfer contact is not making
connection. Quad
Contact is not making connection.
TB2-10 DE-TB1-10 10 0VDC K2 is off.
TB2-10 DE-TB2-1 11 0VDC Wire disconnected from TB5-4.
TB2-10 DE-TB2-2 12 0VDC Wire disconnected from TB5-10.
DE-TB2-3 13 NA NOTE: this is a shield wire connection
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