500-series plug-in connector

500-series scopes (53x, 54x, and 55x) and 127, 132, 133 have bays that take letter-series and 1-series plug-ins which typically control the vertical axis of the display. Two exceptions are the 555 and the 536. The 555 takes four plug-ins: Two letter-series and 1-series plug-ins control vertical deflection of the two beams. Two 555-specific timing/sweep plug-ins (21, 22, 21A, 22A) control the horizontal deflection of the two beams. The 536 takes two letter-series or 1-series plug-ins; the left one controls vertical deflection and the right one controls horizontal deflection. 580-series scopes use their own plug-ins.

The pinout on the connector is as follows:

Pin number	Function
1	Signal +
2	GND
3	Signal -
4	Trigger - 544, 546, 547, 549, late 555s, and 556
5	Trigger + 544, 546, 547, 549, late 555s, and 556
6	Sawtooth (on 556 only?)
7	Alt Timebase sync (on 547 only)
8	Multi-Trace Sync
9	-150 V DC
10	+100V DC
11	+225V DC
12	+350V DC
13	6.3V AC relative to pin 14
14	6.3V AC relative to pin 13
15	+75V DC
16	Multi-Trace Sync

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  pinout shown in 1A2 schematic

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  front pins

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  rear soldering lugs