A Low-Cost Replacement Charger for the Gilson Macroman (2014)

The Gilson Macroman is a battery-powered pipetting aid, and the unit we work with dates to around 2014. It has since left the catalogue, which makes finding an official replacement charger a problem. The only OEM-style units we could track down were held by third-party sellers, and they were priced absurdly — roughly 100 to 300 USD for what is, electrically, a very ordinary wall adapter.

So we put together a substitute. Inspecting the original charger showed an output of 9 V at 0.67 A (OEM model 3A-068WP09), terminating in a small 3.5 × 1.35 mm barrel plug. We assumed — correctly, as it turned out — that the Macroman has a charging board inside that regulates what actually reaches the battery, so the external supply only needs to provide the right voltage and at least as much current as the original.

On that basis we bought a generic 9 V, 1 A adapter with the common 5.5 × 2.1 mm barrel jack, plus a 5.5 × 2.1 mm → 3.5 × 1.35 mm step-down adapter to match the Macroman's socket. Total cost was a few dollars, and it has charged the unit without any issue since.

If you are staring at a three-figure price for a Macroman charger, this is worth trying first. As always when substituting a power supply: confirm the polarity (centre-positive) and the voltage before plugging anything in, and proceed at your own risk.

The linked manual above is the older hardware revision's user guide, kept here for reference since it is no longer easy to find.

Good luck with your own search.