PSU5 No Noise WPC89 Pinball Mounting Thought

[Dr_Dude]

I have used the PSU5 No Noise on my IJ and FT for some time. No issue. Works as advertised, for me.

This post is simply a "think before you do" message: Please make sure that your nut does not grind into the board and the underlying trace.

The image shows the exact nut used under the original LM323K in my WPC89 Power Control Board (PCB). In this case, the star washer overlaps with another trace ('output' perhaps? I didn't look long enough to concern myself). Anyway, here's the image:

PSU-5 mounting: Screw is too close

The solution is easy: Use a smaller nut, or in this instance, I used nylon washer as an insulator and the nut & bolt from my PCB.

PSU-5 mounting: Use a smaller nut

PSU-5 mounting: Use a nylon washer

Finally, the PSU5 does not need a heat sink. That's the whole point and you knew this. But I like leaving the heat sink in-place as it looks authentic.

[Golga]

The simple solution is to flip the screw around so the nut is on the bottom. I also removed the washer from the bottom of the nut and solder it to the ground of the bottom of the board for better connection.
That's what I do anyway and I've installed 50+ of these easily.

[Dr_Dude]

It's been a year since posting. I don't frequent this forum, but I recently installed another PSU5, thought about this topic, saw @Goiga's comment and a post by another: viewtopic.php?f=9&t=10394&p=11247#p11247.

• Flipping the bolt such to place the smaller head on top is quick and easy. A good approach.
• Most will likely continue to use the TO-3 insulator and use a smaller nut

Mounting the PSU5 is also discussed here:
viewtopic.php?f=9&t=10410

TL;DR
For the pedantic (me), I offer a few pictures from my last install to think about.

In my case, I like to place a nylon washer on top to separate / insulate the topside nuts. This means I get ground from the underside so I need to assure there's nothing to grind/short. I won't be using the typical insulator (most people will definitely keep the insulator). Well, the underside of the PSU5 does not seem to have any traces just 2 contacts for ground. Great, easy peasy. To establish good continuity a big nut will sit on those contacts:

The underside of an ezSBC PSU5 No Noise

Although absolutely not necessary, I continue to use the heat sink. Here I use two nuts for contact to ground, raising the PSU5 off the heat sink:

Raising the PSU5

The final result shows the nylon washer, that the #8 nut won't grind into the circuitry on the top, and I added an acorn nut for good looks:

Final result

Last for those who have never worked with a TO-3 component-package (a can), your PSU5 only inserts one-way: