Hewlett-Packard 6177C Current Source

I picked up a used HP 6177C Current Source on Ebay for about fifty dollars, plus shipping. Based on the sellers description, I thought it might work right out of the box, but it doesn’t at least not very well.

I’ve started troubleshooting it, but I decided I had a few other incomplete repair projects that were more important, so I’ve shelved it for now, but I thought I’d use this page to collect together some information on it.

The basic details are:

  • Adjustable current up to 500mA
  • Adjustable voltage limit up to 50v
  • Manufactured in ~1984. The design is older, the users manual is dated 1975.

I think some of the Power Designs bench power supplies I have were designed in a similar era, and I must say, from a mechanical point of view, I think the HP is superior.

The chassis seems to be based on a standard design system that can be used for a variety of devices. For example, the HP 6114a and 6115a precision power supplies use a similar, but taller frame and side panels. Even within a given envelope, the frame can be drilled to accommodate various mounting points.

The electrical assembly seems better too. My Power Designs supplies have hand-soldered PCBs, and all the interconnects are soldered. The HP has a sort of daughter card with the big electrolytic capacitors that connects to the main board using an edge connector. The front panel controls and meters are wired to a connector that slips over a line of header pins on the main PCB. The components on the main PCB are wave soldered.

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