Signal Selector 8520C Disassembly (Figure 5-20); Quad Peak Detector Board A3; Controller Board A1 - Honeywell Chadwick-Helmuth 8500C Maintenance Manual

Chapter 5 - Maintenance And Repair
5.8.1.2.2 Distribution Board A5
a. Unplug ribbon cable from A5J2.
b. Unplug A5 ribbon cable from disk drive (10).
c. Disconnect connectors A5J3-A5J6 from distribution board A5.
d. Remove two nuts (49) and remove distribution board A5 from disk drive bracket (9).
5.8.1.2.3 Disk Drive Assembly
a. Unplug ribbon cable from A5J2.
b. Unplug A5 ribbon cable from disk drive (10).
c. Disconnect power connector from disk drive (10).
d. Remove four screws (43) and four washers (46) and remove disk drive assembly (10) from
disk drive bracket (9).
5.8.1.2.4 Printer Assembly with Printer Board A1
a. Tear off excess paper and clear paper from paper path by turning paper advance gear
forward to back out paper.
b. Press down on paper holder bracket, and remove paper roll and paper bar 13(13).
c. Disconnect connector 13 (A1J3) from printer board.
d. Remove two screws (29), two screws (43) and four washers (42) and remove printer
assembly (13) (with printer board attached) from chassis (2).
NOTE: The printer board and printer assembly (13) must be replaced as a complete
assembly.
5.8.1.2.5 Harness Assembly (Figure 5-19)
The harness assembly consists of the parts that remain in the chassis (Figure 5-18, (2)) after the circuit
boards, disk drive assembly, and printer assembly have been removed.

5.8.2 Signal Selector 8520C Disassembly (Figure 5-20)

5.8.2.1

Quad Peak Detector Board A3

a. Turn unit upside down, remove eighteen screws (5) and washers (7), and remove bottom
cover (12).
b. Remove four screws (19) and spacers (22) and remove quad peak detecter board A3 from

controller board A1.

5.8.2.2 Controller Board A1
a. Disconnect seven connectors (J1, J2, J3, J4, J5, J6, J8) from controller board A1.
b. Remove two screws (19) and standoffs (8) and remove controller board A1 from chassis
(11).
5-56 Chadwick-Helmuth A Business Unit of Honeywell International, Inc.