What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

D-Sub Pin Mystery

BillL

Well Known Member
I was wrapping up an install today of a MZ30 alternator. I used d-sub pins for connecting an LED, but when the pin seemed a little loose when pushed in. In organizing the terminal bin I came across the garmin supplied female pins and it was more firm for push-in. The brass one took 25-45g for push-in, the stainless steel looking one was 105-120g. Are these two different designs?

IMG_6745.jpg
 
Last edited:
Not unless the external dimensions are the same. Even the SteinAir photos show dimensional differences.
 
You can see a noticeable size difference between standard and high density pins if you lay them next to each other. I just went to the garage and took the picture below for reference.

I agree that those both look the same. Is it possible that one of them just has a manufacturing defect? Do you have a bunch of them or is that the only one?

If there's some sort of mystery connector that we don't know about I hope Walt or somebody swings by to educate us.
 

Attachments

  • IMG_7589.jpg
    IMG_7589.jpg
    387.7 KB · Views: 262
Last edited:
In addition, the 2 pins shown have different BIN color codes. Here is a random website with a decoder.

You can use that decoder to look up the MilSpec number and the dimensions. From the outside (looking at your pic), and from the wire end, and based on the BIN code, they both have the same barrel size size and same 20-24ga wire usage, so hard to tell apart when grabbing from the pile, but you definitely want the right pin mated with the right socket, otherwise they won’t make a good connection, or damage each other when plugging in.

Edit: HD and normal have noticeably different sizes, so somehow you got 2 slightly different pins, and those different MilSpec pins, probably with slightly different internal dimensions.
 
Last edited:
I only remember getting pins from Stein, but wonder if they are a low insertion variant. Not a real scientific insertion test, they were inserted maybe 2 mm, then pushed against a scale. Between the stick slip of the slide and my hands shaking the scale varied quite a bit, but the force difference is significant as the numbers indicate.

I have been searching (in vain) for good dimensional drawings and insertion/withdrawal force ranges. It would seem to be important for the amp capacity.
 
Hi Bill,

There are many manufacturers of this size 20 socket contact which is Mil Spec part number M39029/63-368.

The one on the left in OP's photo is MilSpec M39029/63-368 (Orange/Blue/Gray BIN code), the one on the right is M39029/32-260 (Red/Blue/Black BIN code).

They are 2 different connectors, with very similar dimensions, but I can't find a drawing/dimensions for M39029/32-260, or why they are different, or how you ended up with 2 different version of essentially the same connector.

I can only imagine that different equipment vendors provide what is basically a D-Sub, Crimp, Size 20, 20-24 AWG pin, but end up with different MS numbers depending on the brand.

Maybe someone way down in the weeds of the industry can tell you why there are multiple MS definitions for the (apparently?) same thing.
 
The one on the left in OP's photo is MilSpec M39029/63-368 (Orange/Blue/Gray BIN code), the one on the right is M39029/32-260 (Red/Blue/Black BIN code).

They are 2 different connectors, with very similar dimensions, but I can't find a drawing/dimensions for M39029/32-260, or why they are different, or how you ended up with 2 different version of essentially the same connector.

I can only imagine that different equipment vendors provide what is basically a D-Sub, Crimp, Size 20, 20-24 AWG pin, but end up with different MS numbers depending on the brand.

Maybe someone way down in the weeds of the industry can tell you why there are multiple MS definitions for the (apparently?) same thing.

This may well be it. I have looked at many dimension drawings and none have actual insert/withdraw forces. I suppose that in a "production" environment it is allowable to have different part numbers for vendors and manufacturing process differences for traceability. Having had design control for parts as an engineer and dealing with purchasing on procurement, it is reasonable this could happen.

Stein said vendor differences too but I don't buy the drastic insertion difference for amp carry. I will adjust accordingly and pay better attention to this in the future.

Meanwhile maybe that expert will set us all straight.

Thanks ALL!!
 
I was thinking about this again today; I'm assuming you only noticed this because you were working with individual pins/sockets?

I wonder how many of those have been crimped and stuffed into a connector with nobody any the wiser? Surely at least a few electrical gremlins have beed caused by a connector with a jillion pins in it having one or two loose ones.

Thanks for bringing this up. It's yet another little piece of information to keep in the mental troubleshooting toolbox.
 
I was wrapping up an install today of a MZ30 alternator. I used d-sub pins for connecting an LED, but when the pin seemed a little loose when pushed in. In organizing the terminal bin I came across the garmin supplied female pins and it was more firm for push-in. The brass one took 25-45g for push-in, the stainless steel looking one was 105-120g. Are these two different designs?

View attachment 32202

Not that it helps, but I just went through all my DSUBs that I got with my Garmin connectors and found three different versions of sockets. Of the ~250 sockets that I had, 210 were orange/blue/gray with a silver/gold color shaft, 5 were orange/blue/gray with all gold color shaft (same as the left one in the photo), and 25 were red/blue/gray or black (can't tell) with a silver/gold color shaft (same as your right one in the photo). They all came with the Garmin connectors so I don't know that much of a difference likely exists.
 
Not that it helps, but I just went through all my DSUBs that I got with my Garmin connectors and found three different versions of sockets. Of the ~250 sockets that I had, 210 were orange/blue/gray with a silver/gold color shaft, 5 were orange/blue/gray with all gold color shaft (same as the left one in the photo), and 25 were red/blue/gray or black (can't tell) with a silver/gold color shaft (same as your right one in the photo). They all came with the Garmin connectors so I don't know that much of a difference likely exists.

You sure those 25 are RED-blue-gray and not ORANGE-blue-gray? I found the paints aren't always easy to tell what color they are, except under the right (bright) light. Might look "reddish", but really be "orangey", in which case, they're all the same.
 
The other difference is that one is gold plated and one is nickel plated. Gold for low current but voltage drop sensitive circuits and nickel for power circuits. Nickel is also slightly cheaper.
 
The outer shroud on some of the higher end socket contacts of this type is made of stainless steel. For example, the drawing I linked above for the TE Connectivity contact explains that it uses a stainless shroud.

I believe you will find that the inner socket contacts that actually mate with the gold plated inserted pin contact are all constructed of either copper alloy or nickel and all have a gold plating, typically 50 microns in thickness. As such, the pin-to-socket contact is always gold-to-gold for contacts of this type regardless of the material used for the outer shroud.

Steve
 
Last edited:
Back
Top