Simplex 565-028 — 8 amp expansion power supply board for 4100-family fire alarm panels and Universal Transponders.
Simplex catalogs this board as Power Supply Board, Expansion (8 Amp) — the PC board that sits inside the 740-886 Expansion Power Supply assembly. An installer orders the board rather than the whole assembly when a legacy 4100 or 4100+ cabinet loses its expansion supply but the transformer, chassis and harnessing in that bay are still serviceable.
- Simplex description: Power Supply Board, Expansion (8 Amp)
- Assembly-level part number for the complete supply: 740-886
- Power-limited version of the expansion supply is a different part, 636-645
- Catalogued under 4100, 4100+ and Universal Transponder (UT) equipment
Not a 4100U or 4100ES part. 565-028 does not appear in the 4100U or 4100ES service parts lists, which use different expansion power supplies entirely. Read the number silkscreened on the board you are removing, and confirm the revision letter, before ordering.
