Soemtron designed Prüfgeräte Downloads

This page has downloadable drawings and information for the all of the soemtron.org designed Prüfgeräte.  Updates and corrections to the drawings are uploaded on an ad-hoc basis as they come to hand, but we do not accept responsibility for their subsequent use.  To download the files right click the relevant link and select "file save as ....".  Some files are in .pdf format so a current copy of an Adobe Acrobat[1] reader will be needed.  Electrical circuits, mechanical drawings and PCB design files will require their native software to be able to open the files (see descriptions below).  All files on this website are ©2007- www.soemtron.org and its group websites[2] or the files respective owner.

If you have any further historical information, circuits, drawings, photographs, data or manuals about the Soemtron ETR220, 221, 222 and 224 or their manufacture, test equipment (Prüfgeräte) or you just know more about the Soemtron companies in general then please let us know, contact us.

	Our new Prüfgerät Click image for a larger version

Prüfgerät
(Extender)

With no original information available about the internal structure of a Prüfgerät, other than that in the Russian manual (pages 184-186) and a production line photo, we have decided to design our own.  Using connections derived from the ETR220 logic and circuit diagrams, Bernard Green's recollections that the Prüfgerät contained “high impedance” inputs, the data gleaned from our own ETR220, 222 and 224 machines along with whatever other information we could deduce from the Russian manual, we have put a circuit together.

Although we are now using relatively modern op-amps and comparator circuits for the signal detection and LED's for the display, we believe our "Prüfgerät" quite closely mirrors the functionality of the original production line unit.  We have gone a little further than the original Soemtron equipment by adding an extra break-out lead for the V2 power connection, with a pair of four digit panel meters and range switching to monitor the internal supply voltages of any ETR22x under test.  This should prove very useful when setting the core memory supply voltages against temperature.

	Extender Click image for a larger version

Extender
(Prüfgerät)

One of the first bits of test equipment we build was an extender board.  31 pin DIN style connectors for the Soemtron boards are no longer available and attempts to remove them from scrap boards were not very successful, so we built our own connectors utilising a custom PCB to replicate the 31 pin connector layout and spacing, and an aluminium panel.  The extender is also capable of holding an 8 way display board that we had previously designed along with flying lead test clips so that various signals on a board under test can be probed and monitored, albeit in a rather rudimentary way.

Pins for the connectors were sourced from Harwin (P#H2170-01 pins, and H3194-05 sockets) and our grateful thanks go to them for their help with this project.  This bit of kit has proved invaluable in decoding the inner workings of our Soemtron ETR series calculators.

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