Nicolet 526

The Nicolet 526 is a signal averager that is used in a modified OEMed Tektronix 5110 (5103N/D10) mainframe. The modifications to the mainframe performed by Nicolet include

adding a perforated panel for fan cooling via the bottom panel of the scope,
adding a 12-pin connector on the rear panel of the scope
connected the 12-pin connector to the interface board, connector J604.

The 526 has its own +5V regulated rail. An external source of +7V unregulated DC is routed from thee 12-pin rear connector to the mainframe interface board, and into the plug-in. An LM323 +5V three-terminal regulator is the source of the +5V rail within the Nicolet 526. (Even though the input is marked "+7 UNREG" on the board, it should probably be +7.5V minimum, per the LM323 datasheet.) Since the LM323 is rated for 3 amperes, it is unlikely that the plug-in sinks more than that from the "+7 UNREG" input.

Mechanically, the Nicolet 526 is a three-bay 5000-series plug-in. It mates with the center-bay plug-in connector. The Nicolet 526 is made of four boards and a backplane. Connection to the Tektronix mainframe is done via thee backplane. The four boards are:

ADC and Register
Address
Control
Memory

The design makes heavy use of 7400-series digital logic in DIP packages. The printed circuit boards are two-layer. The memory is an array of Fairchild 2102DC MOS 1k x 1 static RAM ICs, DIP, soldered in place.

The wires connecting the backplane board on the 526 to the mainframe interface connector on the 526 are labeled: