HP34401A Repairing front connectors that are worn.

[TF567577]

Hi,

I had an HP34401A that had loose connectors on both of the front and and rear input connectors. I used some copper piping found on amazon that was almost the same size. It was 5mm external diameter and just under 4mm internal diameter. Picture one shows the first attempt at forming the flat end and bending, the corner split. I then annealed the copper by heating and then quenching this allowed the copper to be bent and squashed flat shown in picture two.
The plastic surround for the connectors holes were reamed out to 5mm to allow a snug fit with the copper pipe, the inside of the pipes were also reamed out to 4mm shown in pictures three and four. The copper flat parts were bent to fit into the plastic housing shown in pictures five and six.
The ends were then cut down to length and then cut so they fit through the circuit board shown in pictures seven and eight. The connectors were then assembled and soldered into the board shown in picture nine. The last picture shown shows a quick test of the resistance before calibration. The connectors seem to be a nice tight fit hopefully they will last.
I made a few mistakes :- I didn't really take any measurements of the pipe lengths, it would be helpful if I have to do it again. I caused a very small amount of heat damage to the PCB (picture nine), these draw a lot of heat away due to the amount of copper so you need a good soldering iron. I cracked the plastic holding the small red hooked bit of plastic at the rear of the connector shown in picture nine, you have to be a bit careful fitting the connector to the PCB.
I hope this helps

Cheers

[Swake]

Repair? This is an upgrade !

[alm]

Very neat job! Were the originals plated?

Do you have a link to the pipe you bought so other people can try to find something similar if they have the same problem?

[TF567577]

Hi,

The originals were just bare copper and here is a link to the pipe

https://www.amazon.co.uk/dp/B07X7DGK91?ref=ppx_yo2ov_dt_b_product_details&th=1

It is not quite the same size so you may find a better source. If not you have to ream out the inside of the pipe and the holes in the red housing.

Cheers

[inse]

If one prefers plated brass bushings, either these screw-in bushings or the rear part of those plugs could be repurposed as well.