If your coax power plug loses connection easily, read this

[Astro-Geek]

This fault may be very rare, or maybe not.....   (I'd never seen it before).

I've been tinkering with a secondhand Meade LX200 classic fork mount where the original owner had de-forked it when it stopped working.

I bought it to make a very sturdy motorised mount for my monster 40x100 Helios Bins that weigh 7kg., ( and anything else for testing etc.)

I fixed the fuse blowing problem easily, thanks to all of the advice on the web about replacing the exploding tantalum capacitors ( 😲 ).

Anyway.... back to the reason for this thread, it had another annoying fault of having a temperamental power connection.

The coax plug could only be pushed about halfway in and was prone to losing connection if touched.

I examined the chassis coax power socket closely and could see that the outer "prong" wiper that presses against the sleeve of the coax plug wasn't moving outwards. After removing the front plate I found that the coax power socket had a serious manufacturing defect. The metal sleeve halfway down had a slot cut in it that should have been in line with the slot in the plastic barrel, so that the wiper could move outward under tension when the plug was pushed in.  On this one however, the slot in that ring was twisted round, (as per the attached picture, so that it stopped the plug from being pushed in more than halfway.  I managed to carefully twist it back in line (quite stiff though), and now the wiper moves out correctly and grips the fully inserted plug reliably.  No more power dropouts...

So, if any of your coax power plugs only go in halfway, and are sensitive to dropouts, it may be the same fault....

(Sorry this has been such a convoluted waffle, but it's a hard thing to describe clearly !

[johninderby]

Those sockets are prone to failure.

A NATO stamdard power plug amd socket perhaps? 🤔

[Geoff Lister]

The 5.5mm OD/2.1mm ID jacks usually come with the outer sleeve length options of 10mm & 14mm. I tend to use the 14mm, to ensure that the jack reaches the bottom of the socket, with just a bit of the sleeve visible.

Most of my mounts have an added strain relief clamp, near the socket. I pass the lead through the clamp, with a short loop of wire going to the inserted jack. This stops the jack being disturbed by mount rotation.

Geoff