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Viking II SW3 Numbering




 
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Author Topic: Viking II SW3 Numbering  (Read 349 times)
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wa2fxm
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« on: July 18, 2019, 09:14:15 PM »

I'm trying to verify the wiring on a Viking II which has both the keyer and screen voltage regulator mods installed (to what degree of accuracy I'm not sure). The official Johnson "Modification A" instructions for incorporating the screen voltage regulator mod uses numbers to denote the terminals on SW3. From inspection it would appear that terminal 1 is at 6 o'clock and the numbering continues CCW around. In my case the orange wire is at 3, purple 4, green\white 5 etc. Section A is 1-3, B is 4-6 and C 7-9. I'd just like to verify that this is indeed the numbering scheme.

Also, the instructions call for wires to the terminals on the front deck of the switch. I've got 2 wires on the front deck which do not match the instructions. What I really want to know is where the front deck of the switch shows up on the schematic. Is the front deck really doing any switching or are the terminals just being used as tie points?

WA2FXM Mark


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MikeKE0ZUinkcmo
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« Reply #1 on: July 20, 2019, 11:01:49 PM »

Does the "mod" you refer too, replace SW-3 with a multi wafer assembly?  

I ask because according to the schematic and the picture in the manual I have, SW-3 is only a 2 position switch, AM/CW, with terminals on only one side.  





In the schematic, Pole "A" Applies B+ to the modulator plates, Pole "B" shorts out the modulation transformer secondary in "CW", and Pole "C" switches the Oscillator Cathode to the Key jack.   I don't see any mention of a "D".

There seem to be a few "Conventions" regarding the callout of wafers, terminals, and sections of wafer switches.  

One, numbers the switch sections A, B, C, etc with each side of each wafer being denoted by a letter, with "A" being the front side of the wafer closest to the front panel, while the rear side of that wafer is "B", the next wafer being "C" and "D", and so on.

Another scheme is to number the individual wafers 1, 2, 3, etc, with "!" being closest to the front panel, then call out "F" for the front side, and "R" for the rear side.

In this case of SW-3 having only 2 to positions, each "Pole" is numbered, in the schematic, as "A", "B", "C", and "D", and I don't see "D" being used.   Switches with as many as 4 poles can be implemented on one side of a wafer, depending on how many positions are needed per pole.

Sometimes, though apparently not in this case, there will be a note defining the position of the switches as shown in the schematic.

As for wires of differing color, or added wires, I would think a little time with a VOM would clear up those issues.
    
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Mike KE0ZU

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wa2fxm
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« Reply #2 on: July 27, 2019, 08:43:23 AM »

Does the "mod" you refer too, replace SW-3 with a multi wafer assembly?  

I ask because according to the schematic and the picture in the manual I have, SW-3 is only a 2 position switch, AM/CW, with terminals on only one side.  

Hi Mike. I have two Viking II's, one with only the screen regulator mod and this one with both mods and they both have dual wafer switches. I don't believe these switches are included in either of the mod kits. Neither of the instructions mention replacing SW3. Only moving and replacing wires to it, and the regulator mod instructions include wiring to the front and rear decks. Meanwhile the updated  "Revised 12-16-52" schematic which includes the regulator mod shows no extra switch pole. And the separate keyer mod schematic omits the switch entirely. I guess I need to go back and retrace the wiring moves from stock through the 2 mods and figure out what's going on.

WA2FXM Mark
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