Eltek SMPS 1800SI Connection Mod

The Eltek SMPS 1800 SI 48v switch mode power supply is capable of supplying 37.5A (1800w) so is great for powering 48v amplifiers. The only issue, which is common to most rack mounted SMPSs is they have proprietary connectors on the rear meaning a datasheet or manual is required to know which pin does which.

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All I wanted was 240v in, and 48v out on connectors.

Chassis Mod

For the 240v input to the SMPS I decided upon a standard IEC connector so a normal “kettle lead” could be used when out and about.

At first I made a cardboard cutout for a template. Removing the case from the Eltek SMPS I found a place on the rear section where an IEC connector would fit, marked it, then drilled as much of it out as I could.

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After drilling the hole I used a hand nibbler tool to remove the rest of the metal needed to allow the IEC connector to fit.

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SMPS Connector Removal

While the case was off, I decided to remove the proprietary connectors so they couldn’t short on anything when the PSU was in use, especially the 240v and 48v pins, the 240v pins would be live from the IEC connector being wired in parallel, and the 48v pins as my intention was to bring a DC cable out a grommet on the case to Anderson Powerpole connections, bypassing the connections on the rear.

The easiest way to remove the connectors was to simply the connecting bonds from the connector to the PCB then unsolder the remaining sections of the connecting bonds one at a time, this meant less heat was needed as there was less length on each bonding, and a row at a time could be removed so all 3 rows could be dealt with, the same was then done with the other connector (not shown).

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Live goes to pins 22 & 24, Neutral goes to pins 26 & 28 and Earth is pins 30 & 32.

PCB Connections

NOTE: As was pointed out by G8DOR, the pin numbering on the AC input connector, is different in the manual to the numbers printed on the PCB.

AC_Connector DC_Connector

Final Assembly

After the 240v IEC connector was fitted, and both the IEC and the 48v wires were soldered to the PCB the case was put back together.

I then found 25mm plastic trunking cover fitted the openings where the connectors where so glued them in place so stop fingers getting into the case while fitting the IEC cable if the PSU is facing away from you.

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1 Comment

  1. Baz

    Hi and thanks for the interesting article.
    Beware, the pin numbers and function of the AC input on the ‘PCB Connection’ picture are wrong,
    Live actually goes to pins 22&24, Neutral goes to pins 26&28 and Earth is pins 30&32.
    You can see the tracks and actual pin numbers in your photo after the connectors were removed. They are great power supplies for the big FET linears.


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