TTI TSX Series Service Manual page 38

From May 94 OPTO1 became an HCPL-4503 (Part No. 27001-0030), R133 became 3k3 and
R128 a S.O.T. (typically 68Ω); the main pcb became Iss 5 to accommodate this 8-pin device. The
high C.M.M.R. of this opto improved immunity to conducted interference from both AC input and
DC output terminals. At the same time the collector of Q3 was returned to VRECT- via link LK4,
instead of to the base of Q7, to eliminate the long soft-start after primary overcurrent trip caused
by certain unusual load conditions. Refer to schematic for Iss 5 Main onwards.
From October 95 the main pcb was modified (Iss 6) to add a 22uH choke, L2 (22154-0130), in
the VRECT+ line to reduce conducted emissions, and pcb fuses F2 to F8 to ensure safety in
"single fault" conditions. At the same time, 10N decoupling capacitors were added across the rear
panel terminals and to ground to improve EMC RF immunity.
Fuse values are as follows:
F2, 4
F3, 5, 6, 7
F8
Refer to schematic for Iss 5 Main onwards for fuse positions.
From December 95 the main pcb was further modified (Iss 7) to add C78 (220pF, 23427-0384),
R213 and R214 (both 1kΩ, 23202-2100) to IC5-D to improve EMC RF immunity when in Constant
Current mode.
375mAT
3AT
100mAT
22315-0440
22315-0457
22315-0402
37