HP 25 new internal power supply

[PANAMATIK]

(05-01-2021 12:19 AM)Dreato Wrote:  I just obtained an HP 25 with a new style of internal power supply I've never seen before. It's on a daughterboard, and supplies +6, -12 and 4 volts, as the old style does, but has fewer discrete components. It's got a couple of electrolytic caps, and 2 inductor circuits. The calculator chip complement is different, too.

Can anyone enlighten me?

I found this daughterboard power supply also in an HP-21 and HP-29C. It seems that assembly was optimized by producing these boards. As the power supply had many discrete components, I can imagine that automatic assembly was more efficient with this method.

Bernhard