Compaq Motherboard Power 14 pin

14 pin Molex 39-01-2140 connector at the Compaq motherboard.

The Compaq Motherboard Power 14-pin connector is a proprietary DC power interface used on Compaq Deskpro EN and EP Small Form Factor (SFF) desktops from the late 1990s to early 2000s (Pentium II through early Pentium 4 era). It uses the Molex 39-01-2140 14-position Mini-Fit Jr housing — physically the same shell family as ATX 20/24-pin connectors — but carries a completely different signal map that is incompatible with standard ATX power supplies. The power-on control signal, labelled ON/STBY, is active-HIGH on Compaq PSUs, the inverse of the active-LOW PS_ON# used in the Intel ATX specification, making cross-connection hazardous to both the motherboard and the power supply. Two pin-assignment variants exist: one for BX-chipset boards and one for boards based on the Intel 810, 810e, and 820 chipsets.

Motherboards with chipset 810, 810e and 820

Motherboards with chipset BX

Notes

• The connector housing is a Molex 39-01-2140 (14-position Mini-Fit Jr). Although physically compatible with the housing family used by ATX 20/24-pin connectors, the pin assignments are entirely proprietary to Compaq and must never be substituted with a standard ATX supply.
• The ON/STBY control signal is active-HIGH on Compaq power supplies. Standard ATX PS_ON# is active-LOW. Connecting a standard ATX supply to this board, or vice versa, will prevent normal power-on sequencing and may permanently damage both the power supply and the motherboard.
• The same 14-pin connector and signal map is used on the Compaq PDP-115 power supply (Compaq part 165997-001) shipped with Deskpro EN/EP SFF systems; this connector is therefore documented under both the motherboard power and PDP power supply pages.
• Pin assignments differ between BX-chipset boards and 810/810e/820-chipset boards, primarily in the handling of the 3.3V sense and fan-control signals — verify which chipset is fitted before ordering a replacement PSU.

Signals

• +3.3V — main 3.3 V supply rail.
• +3.3V aux — auxiliary 3.3 V rail; present in the 810/810e/820 variant.
• +3.3V sense — 3.3 V remote-sense line used by the PSU to regulate voltage at the load; present in the BX variant (pin 8).
• +3.3V sense return — return path for the 3.3 V remote-sense line; BX variant only (pin 7).
• +5V — main 5 V supply rail.
• +5V Aux — standby 5 V auxiliary rail; remains powered when the system is in soft-off state.
• +12V — 12 V supply rail.
• -12V — negative 12 V rail, used for legacy serial-port signal levels.
• RTN — power return (ground) for the supply rails.
• ON/STBY — power-on / standby control signal. Active-HIGH (logic HIGH turns the system on); this is the inverse of the standard ATX PS_ON# active-LOW convention.
• Fan OFF # — fan-control signal; when asserted, instructs the PSU to turn off its internal fan (active-LOW in the 810/810e/820 variant; unlabelled logic sense in the BX variant).
• Fan speed — analogue or PWM signal reporting fan speed to the system; present in the 810/810e/820 variant (pin 7).

References

• Compaq Deskpro EN 6550/6400 Service & Reference Manual (Doc 133756-004) — Connector Pin Assignments
• Compaq Deskpro EN Series Maintenance & Service Guide (Doc 314271-001) — System Board Overview

Category:Power Supply Connectors