School me on machined pin sockets

xodaraP

Member

Donor 2015
Joined
Jul 19, 2015
Messages
351
Reaction score
3
Location
Gold Coast, Queensland, Australia
Hi guys,

I've recently been doing some repairs and replacing sockets on a few older boards due to corrosion or a bad connection and have once again contemplated machined pin vs standard sockets.

Machined pin sockets tend to get a bad rap mostly due to bad installation, but I don't understand what causes the installation to end up going bad and ruining a board. I assumed the new socket would go into where the old one did, though the machined pin would obviously require a cleaner through hole than a normal socket may require.

Is there any reason to forgo machined pin sockets in favour of standard sockets when doing a repair?

Is there any reason not to use a machined pin socket to socket a chip that would otherwise be soldered directly (looking at socketing some SRAM on a Sega board that needs replacing)

What causes people to mess these up and ruin a board?
 
It's not the machined pin socket that can ruin a board, it's bad soldering and desoldering is easier to damage a board with a machined pin socket. We tend to "teach" anyone to solder. Now imagine the least patient person, with 10 giant thumbs using a non temperature controlled iron with 30 year old solder. That's probably like 50% of the user base.

If you put too much solder on while installing the socket, the solder can flow up in between the pad and the round base. It can make it difficult to desolder for the best user. The solder won't be fully removed and trying to remove the socket will lift up the pad and trace. This isn't as easy to do with a dual wipe socket.
 
So the pin doesn't seal the hole and prevent the solder from catching at the base of the pin? I thought the pins on these were wide enough to seal the through hole thereby preventing that problem (and also providing better contact)

Is it worth going for the rows of machined pin headers you snap off to the size you want and using these over a socket? It would be nice to have the ability to see underneath ICs for traces while fault finding.

Or should I just completely stay away from machined pins?

My main reason for wanting to do this is to have the most reliable option, the age of the Sega System boards means they're extremely fragile to repair so not having to desolder a failed RAM chip in the future is a definite advantage, but I don't want to install machined pins if they can potentially cause a failure point and are impossible to remove. But I definitely DO want to install such a socket if it's going to be more reliable.

I'm definitely beyond the point of 10 giant thumbs/non temperature controlled iron (I don't believe my solder is 30 years old, I bought it 6 months ago but have no idea how long it sat in a warehouse after being manufactured) - but I've certainly been there and have the previously botched (and now fixed) repair attempts to prove it :p but I certainly wouldn't rate myself a soldering god either, I'd put myself as a 6-7/10 (above average, nowhere near perfect)
 
Last edited:
IMO... if you are competent at soldering them, then use those if you want. Once they are in, in theory, they should never need to be removed.

Use of them vs non use of them is almost a religious thing around here :)

That being said, I mostly use dual wipes, but I have used machined pin sockets before, and have a number of them, so I'm sure I will again.

Beyond good installation, and if something goes wrong, removal, the only issue is they can be more touchy on an IC install.... not by a lot... but some. In which case they bend legs. So, if the next person down the line to work on that board is careless.... they might take out an IC that way.

As for longevity.... I honestly don't know how they stand up in terms of corrosion, connection quality, chip creep, etc.... maybe others more in the know can comment on those factors.
 
Machine pins should be avoid with IC chips that have been soldered before and Custom IC chips with fragile legs from my experiences.

I do like Machine pin sockets when I need to verify that socket is soldered in or you have traces running between the legs of the IC chip. I can do visually inspection for solder bridges..

Removing a machine is can be tricky. Old PCB boards don't like to be over heated and will tend to burn the board and lift the traces.

Use a little common sense and you should be fine.
 
Here's all the schooling you need:


Don't use them on arcade boards.


Machined pin sockets have their place. They're good on small, thick boards, and used on F-14 fighter jets, and other high-vibration, high-G places, where you do not want your chips to fall out.

But on these arcade boards, they are nothing but trouble. I repair many boards with them (which have been added by other people, in past repairs), and they are very frequently the cause of problems, so much that I automatically replace them when I see them, period. There are a couple of reasons:

First, the pins are thick and round, and they tend to plug up the round holes in the boards, which can prevent solder from flowing all the way through to the top side of the board. This is important because on Atari (and other) boards, many of the traces are on top. Technically everything is connected through the plated vias (i.e., the holes in the board), which should run all the way through the board. But the problem comes from when those vias and/or traces get cracked. You need the solder to get all the way through to the top, to hold everything together.

The second issue comes from flexing. Atari PCBs in particular are relatively thin, for how big they are. As a result, they flex a lot. Machined pin sockets are much more rigid than dual-wipe leaf sockets (which allow the pins to slide up and down in the plastic frame a bit). So, when you flex a board with machined pin sockets (particularly Gravitars, which have some of the large vector ROMs placed horizontally in the middle of the board, where it flexes the most), CRACK, the traces and vias will break right under the sockets. And they're a serious pain to troubleshoot and find (in addition to removing the machined pin sockets themselves, which also is a PITA).

You can use machined pin sockets and get away with it (i.e., they aren't guaranteed to cause issues all the time), but statistically, with these boards, you will have more problems with them than if you use dual-wipes exclusively.
 
Last edited:
YMMV :cool:

When I build *NEW* boards such as a Quantum or Omega Race (hi Doug) or Major Havoc, I use machined pins. I prefer them. (And in these cases, I will be populating with NEW ICs).

There are those instances, however, where a dual-wipe is better.
For example, if I'm planning on inserting a daughtercard (High-Score Save Kit), then those pins tend to be larger diameter and would not fit well in a machined pin. So, it's good to have a supply of dual-wipe 40 pin sockets in stock. (Arguably, you could have a machined socket soldered to the PCB and then add a dual-wipe to it for the daughtercard).

When I repair boards, it's a case-by-case for the type of socket I install.
And sometimes I don't use a socket, I would prefer to use two inline SIP sockets so that I can "see" the traces between pins and any solder-buildup that might occur. These are especially handy for RAM where there are many parallel traces under the IC.

20131231111307KLS1-209-1.jpg


YMMV :cool:
 
Let me just add this: If you're going to go with machine-pin, buy name-brand sockets from a reputable source and don't be tempted by cheap Chinese crap you find on eBay. They may look about the same on the outside, but it is what is inside that makes all the difference (yes, each pin contains an insert that actually grabs the IC leg).
 
I personally like machine pin sockets, but like everything, they have their advantages/disadvantages (many of which have already been discussed).

The one thing I'd mention is that if you do plan to use two SIP sockets rather than a DIP socket, it makes safely removing the chip from the socket harder, since there's no plastic base... so you'll be prying against the PCB (so use a tool that won't gouge the traces), and the PCB is farther away than the base of a socket typically is, which makes the chip pry out of the socket unevenly. Obviously it's okay if you're careful, but not as easy as sliding a screwdriver in and twisting to pop a chip out.

Let me just add this: If you're going to go with machine-pin, buy name-brand sockets from a reputable source and don't be tempted by cheap Chinese crap you find on eBay. They may look about the same on the outside, but it is what is inside that makes all the difference (yes, each pin contains an insert that actually grabs the IC leg).
I'd say the same goes for dual-wipes as well though... I've gotten some cheap dual-wipe sockets recently that deformed after the first insertion, and upon removal of the chip, the socket was ruined (the bend grabbed the leg and basically pulled inside-out). I've actually had better luck with cheap machine pin sockets. ;)

DogP
 
Last edited:
I used all machine pin sockets on both of my Quantum PUB builds.. Turned out real nice..
 

Attachments

  • 20170126_193441.jpg
    20170126_193441.jpg
    1.2 MB · Views: 49
The pins of every chip I've ever used has a rectangular cross-section.

Maybe I'm missing something about the internal parts of a machine-pin socket, but I've never understood the reasoning for forcing a square peg into a round hole.

I always use dual-wipe.
 
The pins of every chip I've ever used has a rectangular cross-section.

Maybe I'm missing something about the internal parts of a machine-pin socket, but I've never understood the reasoning for forcing a square peg into a round hole.

I always use dual-wipe.

This is the common misconception about machine-pin sockets. The round hole is not holding the chip leg (the entrance is round just to make insertion easier). The round part is called the sleeve, and inside is a beryllium-copper insert (usually referred to as the "clip") with 4-finger (sometimes 6) contacts that grab and hold the chip leg. The datasheet for a good socket will detail the mechanical and electrical properties of the clip.
 
I preferred the square peg in round hole Amish logic better. ;) (made me look ... LOL)

14005-oscillator-socket-dwg.jpg


The other controversy is that:
- dual-wipe only have two points of contact on a flat/square pin
- machined sockets have four (or more) points of contact on a square pin
- more contact areas on a pin implies better reliability and reduced impedance

>> feel free to discuss among yourselves ... :)
 
Last edited:
I would think these are the ticket for those silly Nintendo Vs. daughtercards, however. never tried it myself.

I'd like to mention about previous socket installs though, I don't like when I get stuff in to fix and someone already tried replacing the sockets. I've had boards where I fixed the other problem but they still don't work because they did hacky installs on everything else. I generally just undo whatever they did and desolder the old stuff out and give it a looking over to make sure they didn't murder half the pads/traces in the process. undoubtedly that's happened too.

I found a lot of other stuff where they apparently don't know how to solder very well and they only get about half the pad covered. it's why I place strong emphasis on flowing solder correctly. and having that Hakko FR300 will save you a lot of agony later, and I particularly say that as someone that used a Shack bulb for about 7 years. you'll notice your casualties diminish to almost 0 when you have temperature-controlled tools.

as for machine pin sockets though, I've used them, because GPE was out of the others at certain points. and I think about the subject matter of this thread when I put them in every single time. :p
 
I use SIP machined sockets. It's nice to only have to stock one part and break the strips to fit the application, and I have more confidence in the end result when they're installed right. That said, I would not want to use them if I didn't have decent soldering and desoldering tools, and IC installation and removal tools. The machined sockets are touchier and you can get away with a more in regards to deficiencies of tools and technique with traditional dual wipe sockets in my experience.
 
Here's a detail from the Mill-Max catalog showing one of their common 4-finger clips:

attachment.php
 

Attachments

  • Mill-Max_30.png
    Mill-Max_30.png
    29.1 KB · Views: 123
Back
Top Bottom