Nokia EKSOS N20 DIY carrying case

In preparation of the first hacker event where we wanted to offer ISDN Uk0 service (see ISDN_at_CCC_Camp_2023) we wanted to build portable, self-contained and ruggedized systems from the Nokia EKSOS.

The systems should contain
  • EKSOS N20 shelf with mandatory NCU and some subscriber line cards
  • a number of subscriber ports broken out to RJ45 connectors
  • a 48V power supply
  • an Osmocom_icE1usb plus an embedded Linux board to run TDMoIP for the V5 back-haul
    • should have at least two Ethernet ports so we can also back-haul the Q3 management interface to a remote location
  • some fans for active cooling as it is getting rather hot in the sun outdoor on a camp
  • ruggedized enclosure to make sure the equipment survives transportation unharmed

opened enclosure


The enclosure is made of wooden panels.

wood corpus

Assembled enclousre body

assembled enclosure

Milling left and right sides to accomodate screw heads

Unfortunately the EKSOS shelf mounting flanges contains a number of screw heads and other protrusions, which require the side panels to be milled

milled side panels

Bottom side / gliders

bottom view with stands

Fans / Cooling

Bill of Materials

Qty Description Source
2 Multiplexplatte 18mm 400x250mm (Seitenteile Korpus)
1 Multiplexplatte 9mm 480x268mm (Unterteil Korpus)
1 Multiplexplatte 18mm 480x400mm (Rückenteil Korpus)
4 Teflongleiter 22m grau Hornbach 6163633 (4-pack)
1 Kistenverschluss ohne Schließhaken 93x24mm Hornbach 734963
1 Schliesshaken für Kistenverschluss 25x33mm Hornbach 734974
2 Möbelband links, vernickelt 50x40mm Hornbach 8673847 (10-pack)
2 Kistengriff Metall verzinkt 82x72x10mm Hornbach 8095113
1 Multiplexplatte 9mm 480x400mm (Vorderteil Deckel)
2 Multiplexplatte 18mm 354x100mm (Seitenteile Deckel)
2 Multiplexplatte 9mm FIXME (Ober/Unterteil Deckel)
1 Edelstahlblech 2mm 475x263mm (Luefter/Deckelblech) eksos-fanmount.dxf

Power Supplies

The power supplies are mounted in the rear part of the bottom panel

power supplies and patch panel

48V: MeanWell RSP-150-48

This supply is used for powering all 3 rails of the EKSOS shelf:
  • odd numbered line cards
  • even numbered line cards
  • signaling voltage

I've used the trimmer potentiometer to trim the output voltage to the maximum (+5%).

12V: MeanWell RSP-12-35

This 12V supply is used to power the nanoPi R5S as well as the fans.

Subscriber port break-out

Initially, I started with a 1U RJ45 ISDN patch panel at the bottom of the enclosure. Later, I switched to a PCBA + IDC ribbon cable approach to reduce the amount of manual labour.

Original approach: ISDN patch panel + wiring

This approach was implemented in the first two units. It consists of
  • a 50-port 1U ISDN patch panel mounted to the bottom of the rack
  • three telephone cables of each 16x2x0.6mm
  • three DIN connectors
  • lots of heat shrink tube 1.6mm

manual soldering of telephone wire

Updated approach: Ribbon cable, IDC connectors + custom PCBA

The idea of this approach was to
  • build a custom break-out PCBA which can be slided into the EKSOS shelf (removing a subscriber line card)
  • build a ribbon cable with IDC connectors towards the EKSOS subscriber line card (DIN connector) and a 64pos 2-row header (break-out board)

break-out PCBA

The boards has 16 RJ45 connectors. The center two pins (4+5) are routed to the first (left) IDC connector. The two surrounding pins (3+6) are routed to the second (right) IDC connector. This allows a single break-out board to carry either 16 or 32 subscriber ports.

break-out PCBA

ribbon cable with IDC connectors

ribbon cable with IDC connectors

break-out PCBA with IDC ribbon cable plugged in

breakout board with ribbon cable

subscriber line cards + breakout boards installed in rack

subscriber line cards with ribbon cable + breakout

Bill of Materials

Qty Manufacturer Part Nr Description Source
1 - - printed circuit board eksos-rj45-breakout-for_slot.brd
2 CONNFLY Elec DS1130-S80BP 8-way RJ45 receptacle
2 Adam Tech BHR-64-VUA 2x32pos 2.54mm header
2 Assmann AWP 64-7540-T 2x32pos 2.54mm female socket
2 Harting 09032647828 64pos DIN header IDC
0.2 Wuerth 63916415521CAB 64pos 0.05" ribbon cable, 1m

icE1usb + Linux SBC

Given that we needed multiple Ethernet ports in a Linux SBC with passive cooling, there weren't really all that many options on the market. I went for a nanopi R5S, which has 3 ethernet ports.

nanoPI R5S 12V DC re-work

For some weird reason, the nanoPi R5S only supports USB-PD. There is no straight DC supply connector for feeding e.g. 12V to it. Not even an unpopulated header on the circuit board.

This meant that it simply wouldn't power up at all if 12V were applied from the 12V mean-well power supply in the unit. Luckily, tnt and I came up with some hardware re-work to modify the R5S to accept a 12V DC input without any USB-PD signaling:

FIXME: Describe the rework

Unmodified R5S

R5S with removed resistor

R5S with additional pull-up resistor

Files (14)
20230809_231803.jpg View 20230809_231803.jpg 2.62 MB unmodified R5S USB input section laforge, 08/27/2023 11:34 AM
20230809_233333.jpg View 20230809_233333.jpg 662 KB laforge, 08/27/2023 11:36 AM
20230809_233308.jpg View 20230809_233308.jpg 715 KB laforge, 08/27/2023 11:37 AM
20230809_233231.jpg View 20230809_233231.jpg 658 KB laforge, 08/27/2023 11:37 AM
20230801_203832.jpg View 20230801_203832.jpg 1.72 MB assembled enclosure laforge, 08/27/2023 11:39 AM
20230801_203546.jpg View 20230801_203546.jpg 411 KB milled side panels laforge, 08/27/2023 11:41 AM
20230801_203821.jpg View 20230801_203821.jpg 1.54 MB bottom view with stands laforge, 08/27/2023 11:42 AM
20230804_192817.jpg View 20230804_192817.jpg 2.85 MB power supplies and patch panel laforge, 08/27/2023 11:45 AM
20230805_090346.jpg View 20230805_090346.jpg 2.63 MB manual soldering of telephone wire laforge, 08/27/2023 11:48 AM
20230811_120723.jpg View 20230811_120723.jpg 1.48 MB break-out PCBA laforge, 08/27/2023 11:51 AM
20230811_120736.jpg View 20230811_120736.jpg 1.05 MB ribbon cable with IDC connectors laforge, 08/27/2023 11:52 AM
20230811_120809.jpg View 20230811_120809.jpg 953 KB breakout board with ribbon cable laforge, 08/27/2023 11:52 AM
20230811_140854.jpg View 20230811_140854.jpg 2.6 MB subscriber line cards with ribbon cable + breakout laforge, 08/27/2023 11:54 AM
20230805_160617.jpg View 20230805_160617.jpg 2.09 MB opened enclosure laforge, 08/27/2023 11:58 AM

Updated by laforge 6 months ago · 10 revisions

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