I see people online refer to an RCA test jig, even sharing pictures of what looks like a vintage TV with special sockets on the front for deflection and other things. Having never seen one in real life, what is inside a test jig? Does it have a complete deflection circuit of its own? Does it have a complete video amplifier circuit?

Just a CRT, deflection yoke, (if color sometimes a convergence yoke), and in some cases like color jigs built in the hybrid era an adjustable matching transformer to account for different impedance between tube and SS sweep circuits.

There's no power cord there's no active components (signal tubes/transistors).

CRT
Yoke
convergence assy
neck magnets
speaker
HV bleeder & Meter
Also has impedance matching taps

On the panel you have
CRT, yoke, HV, ground conv, HV meter, speaker & matching
switch or jumper.

73 Zeno:smoke:
LFOD !

During the hybrid era, what style yoke did the test jigs use? A low impedance parallel wound yoke typical of solid state TVs, or a high impedance series wound yoke typical of tube deflection TVs?

Does anyone have pictures of what the impedance matching transformers looked like for horizontal deflection? They must have been ferrite core like a flyback transformer.

The jigs I used were an old RCA & the Sylvania. Both normal
delta jugs with normal yokes. Also kept a Sony around that had
an int H-K short for in lines.
Matching transformer in Sylvania looked like a partial Sylvania FBT.
Perfect preformance was not needed most the time especially on modern sets

73 Zeno:smoke:
LFOD !