Inside the box.

[John Candy]

My RSU is now quite old and, for some while, the condition of the "banana" socket connectors (into which the probes plug) has been causing concern.

The two highest voltage settings (it can be set in 0.5V increments between 1V and 4.5V) cause the probes and the cables and connectors to become quite hot.

Some of the thick brass and steel I have used it on have required a lot of heat!

The 4.5V connector had deformed with the heat and has now disintegrated, while the next lower connector is slightly deformed.

As is usual with a lot of equipment, the case is pop-riveted to deter any attempt to dismantle.
The first job was to order replacement connectors and then to drill out the rivets.

Surprisingly, there was very little dust or fluff inside the box but I vacuumed it anyway.

The photos show how the connectors have deteriorated with the heat and stress of the banana plugs being pushed in and pulled out.
The two highest voltage sockets are being replaced, the lowest being in unused condition.

For anyone else with a work-weary RSU needing repair, the replacement parts came from 
https://www.ebay.co.uk/itm/361453925028

John

[753]

John

I had the same problem some time ago, then decided the plastic sockets are just not up to the job so I turned some up in brass and a better job all round.
I have some 1/4in dia carbon rods bought in error, if they are any use to you I will send them on

Mike

[Andy B]

I think the main problem is that banana plugs have very little contact area - so dirt on them leads to increased resistance, leading to arcing, then surface damage and even less contact area....

I used 4mm gold bullet plugs and sockets when I built my RSU - rated at 93 amps. Also available widely on ebay and other places. The radio control plane fraternity use them with high power Lipo batteries.

Andy

[John Candy]

I have some 1/4in dia carbon rods bought in error

Mike,
Thank you for the offer but I have just measured my rods and they are 5mm.
If my banana sockets ever again need replacing, I will take the advice on using brass.
Regards,
John.