TM500 Series plug-in interface

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Tektronix TM500 mainframes provide power supplies and signal connections for TM500 plug-ins.

Mechanically, the interface is a direct card-edge connector with 28 contacts on either side, at 5/32" (~0.156" or 3.96 mm) spacing. The connector can be keyed in several places, the plug-in boards have matching cuts between contacts (see below).

Looking into the mainframe from the front panel, "A" pins are left of the connector centerline (on the plug-in PCB's component side) and "B" are on the right (on the plug-in PCB's solder side). Pins are numbered from 1 at the bottom to 28 on the top.

The mainframe provides supplies shared by all slots: 17.5 VAC, +11.5 V (regulated from the 17.5 VAC supply), +33.5 V, and −33.5 V. In addition, there are two dedicated, 25 VAC, 0.5 A transformer windings per slot, floating up to 350 Vpeak with reference to the common ground.

In mainframes that have a "high-power compartment", that slot has a separate 17.5 VAC and 11.5 VDC section (floating v-v the other supplies) providing 4 A shared between them, and that slot's 25 V windings are rated 1 A each.

For each slot, two uncommitted transistors (one NPN and one PNP) are heatsink-mounted in the mainframe. These are available for the module's power regulation circuits and are rated to dissipate 7.5 W each.

The signal pin connections depend on the individual modules. For details, please see the TM 500 Rear Interface Data Book.

  A side B side
Pin Function Function
28..14 Signals Signals
13 25 VAC winding #1 25 VAC winding #1
12 +33.5 V filtered DC +33.5 V filtered DC
11 Base lead of PNP series pass Collector lead of PNP series pass
10 Emitter lead of PNP series pass Transformer shield lead
9 ±33.5 V common return ±33.5 V common return
8 −33.5 V filtered DC −33.5 V filtered DC
7 Emitter lead of NPN series pass Collector lead of NPN series pass
6 Base lead of NPN series pass No connection
5 17.5 VAC winding 17.5 VAC winding
4 +11.5 V common return +11.5 V common return
3 +11.5 V common return +11.5 V common return
2 +11.5 V filtered DC +11.5 V filtered DC
1 25 VAC winding #2 25 VAC winding #2

Interface connections viewed from front of power module. Pins 14 through 28 are used for signal connections.

25 VAC winding connections 1A, 13A are in phase, i.e. for 50 Vct connect 1B-13A as for example in the PS502.

Pin group function legend

 DC power and ground
 AC power 
 Uncommitted transistors

Connector keys

The standard TM500 frames simply have a key between pins 6 and 7 as shown in Figure 3-1 from the TM 500 Rear Interface Data Book:

Other keys are added for options, depending on the specific connectivity requirements for families of plugins.

The TM500 Series Rear Interface Data Book details the various positions for the optional barrier keys and are summarized here for reference.

Barrier Key Positions
Pins Purpose Example plugins
25-26 SC502 Family
24-25 Logic Analyzer Family
23-24 Signal Source Family AF501, AM501, AM502, FG501, FG502, FG503, PG501, PG502, PG505, PG506, PG508, RG501, TG501, SC501, SG502, SG503, ...
22-23 TR502
21-22 Measurement Family DC501, DC502, DC503, DC504, DC505, MR501, ...
19-20 Power Supply Family PS501, PS503, PS505, ...
17-18 DMM Family
6-7 TM500 standard

Power ratings

Mainframe Standard slots High-power slot
TM501 +11.5 V 17 VAC 2×25 VAC
1.0 A shared 2×0.5 A
±33.5 V 0.5 A shared
TM502 +11.5 V 17 VAC 2×25 VAC
60 VA shared 2×0.5 A
±33.5 V 0.7 A shared
TM503 +11.5 V 17 VAC 2×25 VAC
3.9 A or 90 VA shared 2×0.5 A
±33.5 V 0.7 A shared
TM504 +11.5 V 17 VAC 2×25 VAC +11.5 V 17 VAC 2×25 VAC
3.6 A shared 2×0.5 A 3.6 A shared 2×1 A
±33.5 V 1.4 A shared
TM506 +11.5 V 17 VAC 2×25 VAC +11.5 V 17 VAC 2×25 VAC
5.2 A shared 2×0.5 A 4 A shared 2×1.2 A
±33.5 V 1.75 A shared
TM515 +11.5 V 17 VAC 2×25 VAC
6.5 A or 150 VA shared 2×0.5 A
±33.5 V 1.75 A shared

See also