apollo psa test point adaptor

Carl Claunch carlclaunch51 at gmail.com
Mon May 20 17:38:11 CDT 2019

On 05/19/2019 09:46 AM, Jon Elson via cctalk wrote:
> There's a switch labeled "IRIG" which stands for Inter Range
> Instrumentation Group, and refers to a standard for
>   telemetry encoding.  There is a standard for time code, a
>   standard for modulating analog signas onto a bunch of FM
>   carriers, and a standard for multiplexing several analog
>   signals onto one FM carrier.

In this case IRIG stands for Inertial Reference Integrating Gyroscope, one
of three inside the Intertial Measurement Unit of the spacecraft. This
adapter is used to test the PSA tray (Power Sub Assembly) which had modules
such as the Coarse Alignment Amplifiers that were used to drive and measure
the gryos (and the accelerometers).

It also drives the sextant optics for star sighting in the CM (thus you see
the knobs labeled Sxt Shaft and Sxt Trun) Those same circutis would be used
with the Rendezvous Radar for the PSA installed in a LM.

>   Apollo documents are probably VERY hard to come by these days.

They are being rapidly and steadily digitized and made available. Many of
the PSA schematics are now accessible. The test point adapter itself is not
going to be easy to find, but you can find the wiring harness schematics
that would tell you what each of your 91 leads in the connector does.


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