Delta DPS-400AB-24 Pinout: 44-Contact Card-Edge Connector, Control Pins, and Bench Use Tips

User question

Dps-400ab-24 pinout?

Artificial Intelligence Response

Direct answer to the question

• The vast majority of Delta Electronics DPS-400AB-24 (and –24 A) units use a 44-contact card-edge / blade connector, NOT a standard ATX plug.
• The connector consists of 6 high-current blades for the main +12 V rail and its returns, plus 24 small signal fingers arranged in four rows (A-D, 6 columns each).
• To run the supply on the bench you usually ground three control pins (PS_ON#, PS_KILL1, PRESENT#) and place a small load on the +12 V rail.

Detailed problem analysis

1. Connector orientation
   Hold the PSU so that the fan/handle faces you and the edge connector is on the right. Blades are at the bottom, small signal fingers at the top. Column 1 is nearest the handle side.

2. Pin-by-pin table

Row/Col	Name	Function / comment	Typical action for standalone use
High-current blades (bottom part)
‑	Blade 1	+12 V	Main output, 30 – 33 A total (paralleled with Blade 2/3)
‑	Blade 2	+12 V	″
‑	Blade 3	+12 V	″
‑	Blade 4	Return	0 V (GND)
‑	Blade 5	Return	0 V (GND)
‑	Blade 6	Return	0 V (GND)
Signal fingers (top rows, 1 – 6)
Row D
D1	12 VSB	+12 V stand-by (~1 – 2 A, always on)	Available
D2	12 VSB	+12 V SB (dup.)	–
D3	Return	Ground	–
D4	48LS	Load-share bus (0–6 V analogue)	Leave open
D5	AC_RANGE	Hi/Lo-line select (open = autoranging)	Leave open
D6	SCL	SMBus/I²C clock	Leave open
Row C
C1	12 VSB	+12 V SB	–
C2	12 VSB	+12 V SB	–
C3	Return	Ground	–
C4	ACOK#	Goes low if AC missing	Optional monitor
C5	PRFL	Predictive-fail indicator	Optional monitor
C6	Reserved	—	Leave open
Row B
B1	12 VSB	+12 V SB	–
B2	12 VSB	+12 V SB	–
B3	Return	Ground	Reference pin
**B4	PS_ON#	PRIMARY ENABLE – active LOW**	Tie to Return
**B5	PS_KILL1	Secondary/kill – active LOW**	Tie to Return
B6	SDA	SMBus/I²C data	Leave open
Row A (nearest handle)
A1	FANP	+12 V fan supply (internal use)	Ignore
A2	PSAlert#	SMBus alert	Ignore
**A3	PRESENT#	Module presence – active LOW**	Tie to Return
A4	PWOK	Power-good (HIGH ≈ 5 V when +12 V in spec)	Optional monitor
A5	FAIL	Fault output – LOW on failure	Optional monitor
A6	FANC	Fan tach / control	Ignore

3. Power-on sequence (bench use)

   1. Unplug AC, identify pins B4, B5, A3 and any RETURN.
   2. Solder or jumper B4, B5 and A3 together, then connect them to Return (e.g. B3).
   3. Connect a dummy load of ≈ 1 – 2 A (e.g. 10 Ω / 25 W resistor or a 12 V automotive bulb) between +12 V and Return.
   4. Apply AC mains. The fan will spin and +12 V should rise to ≈ 12.3 V.
   5. 12 VSB is available at all times for control electronics.

4. Electrical capabilities (typical, check label for exact values)
   • +12 V main: 33 A max (400 W)
   • +12 VSB: 1.5 – 2 A
   • Ripple: <120 mV pp (main)
   • Efficiency: ~85 % at 230 V, 50 % load

5. Variants & confusion
   • A few desktop/industrial versions branded “DPS-400AB-xx” ship with a standard 24-pin ATX loom. Those follow the ordinary ATX-12 V v2.x pinout (appendix A).
   • Always confirm visually; the card-edge version and the cabled-ATX version are electrically different.

Current information and trends

• Converting surplus server PSUs (such as the DPS-400AB family) into inexpensive 12 V bench supplies is now commonplace; many adapter boards on hobby sites simply hard-wire PS_ON#, PS_KILL1 and PRESENT#.
• Recent Delta firmware exposes additional telemetry (voltage, current, temperature, fan RPM) over the SMBus; open-source micro-controllers (e.g. ESP32, Arduino) are being used to read these values for lab monitoring.

Supporting explanations and details

• PS_ON# vs PS_KILL1: Two-level enable ensures safe hot-swap; grounding both emulates full insertion into a back-plane.
• Load share (48LS): A 0–6 V analogue bus lets multiple units share current in parallel. Leave floating for single-unit use.
• AC_RANGE: Older designs needed a strap for 110/230 V; this model autoselects, so the pin is kept open.
• Why a dummy load? Server PSUs are designed around constant-current primary regulation and may trip OV/UV protection if the secondary control loop never sees load current.

Ethical and legal aspects

• Observe mains-voltage safety; enclosure earth must remain intact.
• Modifying or repurposing surplus PSUs for commercial sale could violate original safety certifications (UL/CE).

Practical guidelines

• Mount the PSU in a metal box with ventilation; fan noise can be reduced only if internal temperatures are monitored.
• For 24 V output, two identical units can be placed in series only after floating the DC-GND of one unit from chassis-earth (advanced, safety-critical).

Possible disclaimers or additional notes

• Pin positions may vary with very early/late revisions; always verify with a multimeter before connecting valuable loads.
• The card-edge contacts are not keyed—reverse insertion on an adapter board will destroy the PSU.

Suggestions for further research

• Read Delta spec sheet DPS-SPEC-201 (searchable mirror at CERN) for full electrical data.
• Open-source projects: “OpenPSU-SMBus” on GitHub shows how to log telemetry.
• IEEE-1101.11 and PICMG power-module standards give background on these connector conventions.

Brief summary

The DPS-400AB-24 is normally a hot-swap server supply with a 44-contact card-edge connector. Six heavy blades deliver +12 V and ground; the remaining fingers carry +12 V stand-by and control/monitor signals. Ground PS_ON#, PS_KILL1 and PRESENT#, add a small 12 V load, and the unit will operate as a robust 400 W 12 V source. A handful of rare desktop versions use a standard ATX-24 pin harness—confirm your exact unit before wiring.

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