BBC B+ - repairing a Watford Electronics ZIF (Zero Insertion Force) socket
September 2025 - During the Econet upgrade I had to remove the ZIF socket to aid access to the BBC Motherboard. I thought it would be a good time to find out why it was unreliable. The socket is around 40 years old and has been well used during this time.
The socket is made up from a ribbon cable with headers at each end and a PCB with the ZIF socket an a few passive components, capacitors and SIL resistors.
I started checking the continuity from end to end and found pin 12 did not conduct. I then removed the ribbon cable and checked that - all ok.
So the problem was on the circuit board. Looking at the photo below you can see that pin 12 (top left, three in) clamp is biased to the right and all the others are biased left. Internally the clamp is broken and does not have continuity to the pin below.
I desoldered the broken socket and replaced it with a new one and moved the WE label just to make it look authentic.
Refitting it in the BBC - I removed the AFM ROM from socket 3 on the expansion board and plugged the ribbon cable back into the socket.
And it's working. The socket has the AFM ROM in it and the *ROMS command agrees - ROM position 3 shows AFM.
Another job finally done.
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