C42 Set PSU Grounding Post

[David Dunlop]

Started working again on trying to free up the burled set nut on this post. Not certain how it is all assembled to the lower lip of the PSU so I am a little leery about destroying it in the process of trying to get it to work again.

I have posted a couple of photos of how it looks. The first one is an upper view showing the burled set nut sitting fairly high up on the threaded shaft of the post. The upper remaining post thread and the upper part of the burled set nut show a fair bit of rusting. Below the burled set nut, the thread on the ground post looks to be in excellent condition with lots or original cadmium or zinc plating.

First problem is deciding if it is safer to try and lower the set nut down into the good thread, or attempt to bring it farther up the post thread, where the most rust damage appears to remove the set nut completely.

A second part of the problem is trying to understand how the threaded post was mounted to the lower lip of the CPU. The second photo is a mirror view looking up at the bottom of the threaded post. The head of this post is countersunk to fit flush with the bottom of the CPU lip. On the top face of the lip is a hex nut the post threads through. I cannot tell at this point if this hex nut is welded to the CPU lip, or free to move up the shaft if turned. As you can see, the countersunk head of the threaded ground post just has a concave depression in the centre of it. No apparent screw driver slot of any kind is evident.

If I wrap a strip of thick rubber around the burled set screw and grap it with a pair of pliers to try turning it, it only moves 10 to 15 degrees and locks up and I can feel the countersunk head of the grounding post is moving during this action.

I would not probably be so fussy if I knew a complete replacement grounding post assembly could be had, but until that happens, saving what I have at the moment is the prime issue.

If anyone has experienced this problem or can suggest a solution, please fire away. MLU ideas are always appreciated.

David

[David Dunlop]

Yea! After working on it with WD 40, a strip of rubber and a pair of pliers for about 20 minutes (and two blistered fingers), I now have the nut working the full length of the post. Some wire brushing yet to do but all is once again in good order.


David