1991 C&K descriptions by Herb Johnson July 13 2012 --------------------- For the Ithaca, Kip Yeakel identified these modern (1999 forward) C&K descriptions as compatible with the 1970's C&K switches for the Ithaca Intersystems front panel: Qty. Partnumber. Description. 16. 7101J3V6BE2. Address/Data 2. 7105J3V6BE2. Ex/Ex next, Dep/Dep next 1. 7207J3V6BE2. Single step/Slow single step 1. 7203J3V6BE2. Breakpoint toggle 2. 7205J3V6BE2. Run/Stop, Reset/Ext clear I used the C&K 1991 catalog to review these descriptions and see what they specified back then, and any alternatives that might be compatible. The short answer is that there are not many alternatives. In any event, the C&K catalogs use unfamilar words for the various features of their switches. And it's hard to navigate their catalogs to assemble a part number from their descriptions So I've taken time to name and describe those features in this document. Also, I've noted alternatives for the IMSAI, which uses mostly the same kind of C&K switch except it does not need what C&K calls the "v-bracket" to mount it to the PC board. - Herb Johnson Part number breakdown Of course 71XX is a single pole switch, 72XX is double pole. The XX represents various switch functions and we've discussed them previously. The "actuator" is the paddle or handle and closely associated with the "termination", the rest of the assembly which operates, mounts and connects the switch. These are the most visible parts of the switch. For our purposes, there's either the Ithaca-type U-frame actuator soldered to the PC board; or the IMSAI-type panel-mount actuator which on the IMSAI is not mounted to a panel. So, one can choose the IMSAI-type switches and either ignore the lack of physical mounting, or swap the switch bodies with other Ithaca-type switches that don't have the features needed (or need repair). The rest of the C&K part number describes switch contact materials, actuator color, and other considerations. Actuators J3, J4, and J5 use the same actuator hardware, for mounting to a front panel, but different "handles". These are used on the IMSAI, but the switches are not mounted on a front panel, they are held up by their PC board mounting pins. So they MIGHT be used on an Ithaca but they won't be as secure. Or, they are a source for switch parts. C&K's J3 is the IMSAI off/on type flat switch. J4 and J5 are different lengths of long handles, J4 is 1.174", J5 is 1.049". I measured the IMSAI original handles at about 1.125 (1-1/8) from tip to pivot point. (You can measure the black handles you got on your switches.) The actuator portion that pivots and holds the "handles" is specified (as part of the relevant termination V-series) as .138" from base to center of hole. J10 has a slightly longer actuator panel frame, 1.625" between the panel mounting holes versus J3/J4/J5 at 1.375. Since the IMSAI (or Ithaca) don't panel-mount, this difference does not likely matter. Terminations The Ithaca used a different termination than the IMSAI. Part of the termination frame is what I'd call a U-shaped bracket that mounts and solders to the PC board. (You call these "V-brackets" I believe, not because they are V-shaped, but because of the "V" designation. I suggest calling them "U-shaped brackets" to describe their visual appearance.) The C&K V2-V6-V7-V8 series look like the Ithaca termination framework; and also match the PC board pin spacings for both the switch contact pins and the frame mounting pins (at .250" apart). When selected with the IMSAI-like lever handles (J4, J5) or off/on handle (J3), the pivot for those handles is at the .142" height. These V series vary in height above the PC board. As you noted, the V6 is closest in height to the Ithaca's at .460". The others are the V2 at .555", V7 at .630", V8 at .953". The V21, V61, V71 and V81 have snap-in PC mounting pins but are otherwise identical. There's also V3, V4 and V9 series which have the correct actuator framework but the U-shaped frame PC mount pins are TOO NARROW at .125" apart. Of these, the V3 is closest in matching height at .460"; V4 is .630", V9 is 1.15"; . V31, V41 and V91 are snap-in variations. Terminal pins and terminations The external terminal pins to the switch contacts are also part of the "terminations". The V-series terminations referenced above, apparently only come in short PC board pins .030" X .050" wide and spaced at .190 intervals. So, there's no "descriptor letter" needed to specify these pins, they are specific to those V-series. The J3, J4, J5 panel-mount series come in a variety of terminal pins, so they require a termination descriptor letter. The C style is short PC board pins .050" X .050" wide and spaced at .190 intervals - same as the V-series described above. The W series of W, W1, etc. are wirewrap pins of the same cross section but various lengths - which could be cut down and soldered in. DON'T use Z or Z3. Z are .080 wide loops for soldering wires and are far too wide for the PC board holes; Z3 is a PC mount but at .062 is also too wide. All these are spaced at .190" intervals. I suppose it's possible to chop up the pins and make them work. other terminations The other C&K termination descriptions don't appear to have the same switch contact pin spacings, even if modified, to fit the IMSAI or Ithaca PC board. They also have the wrong actuator hardware, mount at other angles, etc. etc. But it's possible some of them can be hacked to work. Other features "B" is one of many kinds of contact material combinations of gold, silver or tin-lead. It's hard to be choosy these days; except for the AC power switch, it doesn't much matter. But B is gold/gold, K is gold/solder Q is silver/silver, M is silver/solder, G is gold-over-silver/gold, L is gold-over-silver/solder. "E" is the standard epoxy "seal" for the electrical pins to the switch body. "I" is an alternative with more epoxy. I don't believe these matter. Actuator (lever) color is the last digit, 1-9. In numeric order they are white, black (standard), red, orange, yellow, green, blue, brown, gray. Example part numbers I hope --------------------------- 7101J3V6BE2 7100 series single pole J3 is flat handle like on-off V6 is U-bracket PC mount frame (Ithaca like) B is a standard gold/gold contact E is standard epoxy seal 2 is black handle 7207J4CQE3 7200 series double pole J4 is 1.174" long handle C is short solder pin, panel mount (IMSAI like) Q is gold-over-silver/gold contacts E is standard epoxy seal 3 is red handle --end-- Whew! - Herb Johnson