Nikon Lens M/A switch

[sdancer75]

I tried to replace the lens motor but I accidentally cut the cables of the M/A switch.


The cables were originally connected (if I remember well) on the pins 1 and 2 like the 1st photo I found googling it. Ok, I soldered them in this way, but I had always autofocus A/M (no manual mode, even I've switched to M mode).
 


I got some quick connectivity switch position meters and it seems that the switch between pins 1 and 2 is always open circuit as well in all other combinations except only pins 1-3 when it is switched to M/A mode, otherwise is open circuit.

So, to summarise, all pins are open circuit EXCEPT pins 1-3 when only M/A mode is selected.

I tried to solder pins 1-3 like the captured photos and now I get a reverse effect where when the switch is in M/A I have no autofocus (manual mode) and when the switch is in M mode I have autofocus.

I am pretty sure that the correct connection is pins 1 & 2 but this does not seem to work since I have always autofocus.

I am confused about how this switch actually works. In my option, it should work like when A/M mode, pins 1 & 2 should have a short circuit and when the switch is moved to M mode pins 1 & 2 should have an open circuit as a state change or in a reverse way. What do you suggest? How this switch work?

[sdancer75]

Taking closer pictures of the 3-pin switch.

I think that is internally broken, I can not give any other explanation for an SPDT switch.

[Twoflower]

Not sure but I think you connected the switch wrong. Try 2-3. Usually the center one is the one that connects to the ones on the outside.

Edit: Re-Read your text. It seems you measured that with the result it's open in both positions...

[sdancer75]

Not sure but I think you connected the switch wrong. Try 2-3. Usually the center one is the one that connects to the ones on the outside.

Edit: Re-Read your text. It seems you measured that with the result it's open in both positions...

Hi,

In this way, ie. pin 2-3 connected, I get always Open-Circuit despite the location of the switch lever. Take a look in the diagram below.

  PINS
1   2   3
---------
 ||  ----> Switch lever position (all pins are open circuit)


  PINS
1   2   3
---------
      ||  ----> Switch lever position (1-3 pins are close circuit)

[Twoflower]

The 1-3 connection is a bit unusual as I've seen in the past 1-2 and 2-3 connections. I can't remember seen a 1-2 and 1-3 switch. That led me to my post. But one learns everyday something new.

With your observations I agree with your assumption that the switch is broken. I see 3 options: 1. buy a replacement switch, 2 see if you can repair (if you fail, use option 1) or 3. try to fit the switch up side down in there.

[sdancer75]

[ Specified attachment is not available ]

The 1-3 connection is a bit unusual as I've seen in the past 1-2 and 2-3 connections. I can't remember seen a 1-2 and 1-3 switch. That led me to my post. But one learns everyday something new.

With your observations I agree with your assumption that the switch is broken. I see 3 options: 1. buy a replacement switch, 2 see if you can repair (if you fail, use option 1) or 3. try to fit the switch up side down in there.

Ok, I didn't have any replacement switch right now, so I tried to upside down the original one. It worked flawlessly. I was very chary to accept that the switch was broken but indeed that was the problem, very curious......

For the record, if someone will need the following information:

A/M = needs open circuit ( switch OFF)
M = needs short circuit ( switch ON)

[Twoflower]

Nice that you got it working! 

Eventually the heat from desoldering the wires sightly deformed the plastic of the switch.

Happy shooting!

[tkamiya]

You are a very brave person!  It looks like a higher end Nikon lens.  24-70 f/2.8???

[sdancer75]

You are a very brave person!  It looks like a higher end Nikon lens.  24-70 f/2.8???

Hi,

They are pretty cheap lens but insanely good for that level of price.

The lens is the primary Nikkor 35mm f/1.8G