The Tektronix PG506 is a 1 MHz calibration generator plug-in for the TM500 system.
There are (at least) two versions of the PG506. The older version has two relays that switch a low-pass (noise) filter into the 10 V and below ranges. The new version just has a capacitor across the output for these ranges.
Common failure modes: In case of low or no output on the 20 V and above ranges, check Q270, Q280 and Q290.
<gallery> Tek pg506 left internal.JPG|PG506 Left Internal Tek pg506 left internal2.jpg|PG506 Left Internal Tek pg506 right internal.JPG|PG506 Right Internal Tek pg506 right internal2.jpg|PG506 Right Internal Tek pg506 late.JPG|PG506 Front Tek pg506a front.jpg|PG506A Front pg506_new.jpg|Newer version without filter relays Tek pg506a on1.jpg|PG506A File:Tek pg506a output waveform.jpg|PG506A output waeform <gallery>