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EPower module (top view)
EPower module (bottom view)

Brief information

The EPower module replaces the original Enterprise power circuits.


The module has three power sources:

  • 12 V @ 0.7 A,
  • 5 V @ 1.5 A channel A,
  • 5 V @ 1.5 A channel B.

The current limitation of the 5 V stabilizer is set at 3.7 A [I = 37125 / R1] (the maximum possible current is 7 A, if need, but it could damage the circuity of the computer).

Maximum values (limited by used components) are:

  • 12 V @ 1.0 A,
  • 5 V @ 2.3 A per channel (both 5A+5B @ 4.5 A).

This is much more than the original power source (12 V @ 0.15 A and 2x 5 V @ 1 A).

How to install

The author has made every effort to make the module as reliable and safe to use as possible. However,

You make any modifications inside of your equipment at your own risk !

What you need

  • EPower module
  • screwdriver
  • soldering iron
  • tin extractor
  • solder tin
  • pliers

Enterprise mainboard preparation

The following components should be desoldered from the motherboard:

  • C8 (100 µF)
  • C9 (100 µF)
  • C10 (100 µF)
  • C11 (100 µF)
  • C12 (100 µF)
  • D2 (1N4001)
  • D3 (1N4001)
  • D4 (1N4001)
  • L1 (coil)
  • U19 (LM7805)
  • U20 (LM7805)
  • U21 (LM78L12)
  • TR2 (BC337)
  • TR3 (BC212)
  • R13 (100 Ω)
  • R14 (10 Ω)
  • R15 (1.5 kΩ)
  • R16 (3.9 kΩ)
Remove these components
Desoldered components
Prepared mainboard

Installing the module

The module pins are matched to holes left after the components:

  • D2 (both holes),
  • TR3 (ground),
  • C8 (+9V),
  • U21 (output +12V).

The holes in which the module is installed should be very carefully cleaned of tin residues.
Especially the holes after the transistor TR3 and the U21 chip due to their smaller diameter.
Do not force the pins. Despite careful assembly, it is possible to slightly tilt the pins from the vertical.
They should be corrected if necessary.
The position of the pins is very precisely matched and the module should be allow gently slide into place.
When soldering, make sure that the module adheres to the main board (up to the height of pin spacers).
After assembly, cut out the excess of tips with a pair of pliers.

The main stabilizer is intentionally undercut to allow the existing heat sink to be screwed.

   EPower fitting.jpg
Module fitting
   EPower pins.jpg
Cut the excess of pins
   EPower inside.jpg
Installed EPower module

How to make the EPower


EPower scheme.png


EPower pcb.png

Bill of materials (BOM)

RefDes Name Value
C1 CAP_0805 10 nF
C2 CAP200RP 220 µF / 25 V
C3 CAP200RP 15..22 µF / 25 V
C4 CAP200RP 15..22 µF / 25 V
C5 CAP200RP 15..22 µF / 25 V
C6 CAP_0805 470 nF
C7 CAP_0805 1 nF
C8 CAP200RP 180..220 µF / 10 V (low ESR)
C9 CAP200RP 180..220 µF / 10 V (low ESR)
C10 CAP200RP 220 µF / 25 V (low ESR)
C11 CAP200RP 220 µF / 10 V
C12 CAP_0805 100 nF
C13 CAP_0805 330 nF
D1 C3D08060G 6 A Schottky diode
D2 S1A 1 A universal diode
D3 S1A 1 A universal diode
D4 SK110 1 A Schottky diode
L1 DE_1207 22 µH @ 4.7 A
L2 DE_0704 22 µH @ 2.3 A
L3 DE_0704 22 µH @ 2.3 A
L4 DE_0704 15 µH @ 1.4 A
L5 DE_0704 15 µH @ 1.4 A
R1 RES_0805 10 kΩ (current output limiter)
R2 RES_0805 3 kΩ
U1 LM2679T-5
U2 LM2585S-12


Thread on the Enterprise Forever forum Enterprise Power module - EPower

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