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Building a daughter board that plugs into an existing PCB

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I'm trying to build a daughter board that fits into an old PCB and need to tap signals from quite a few existing devices.  Some are socketed and others I have desoldered and socketed. 

Some of the original sockets are of the single wipe type.

I mounted the circuit board using turned headers but cannot get a reliable contact across all the sockets. 

Is there a better way?

Perhaps I should replace the existing sockets with something else? Dual wipe?

I could just solder the PCB assembly direct to the PCB but will have to modify my design as I have solder jumpers that may need to be changed on the underside currently.

I'm particularly interested to know about any alternatives to sockets in this scenario

Once a turned pin has been inserted in a single wipe socket, that socket is compromised, and will never make reliable contact to any thinner pin.  Also as the contact has been deformed, as you have discovered, it may not be reliable even with the turned pin, especially if its aged due to oxide and tarnish buildup on the contact, + the point of contact shifting.

Depending on a dual wipe socket's exact contact design the same may be true for it.

You don't have many options other than replacing the old sockets.  I'd go with turned pin to mate non-destructively with the turned pin headers on your daughterboard, but still allow it to be reverted to no daughterboard + ICs in the same sockets.


Rather than turned pin headers are there more socket friendly options? 

Yes, you can (with some difficulty for small quantities) get flat pin headers suitable for PCB mounting, but as you've already tried the turned pin ones, the sockets on the main board are already compromised, so they wont do you any good unless you have more devices that need this daughterboard.  Also, they are a lot more fussy about alignment than turned pins (where the rounded tip and conical recess of the socket entry make them hard to misalign), and I would expect a significant risk of mis-insertion resulting in curled pins, which with your board's limited access to the middle sockets would be difficult to inspect for or correct.

Yeap. It's all very tricky with the middle section. Perhaps it was a poor approach and I should split the parts up and go for some kind of interconnect scheme... Quite hard in this case with data and address buses.... But do-able.

I might give up and rid myself of sockets and hard solder the whole assembly.


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