(Newbie) How to mount/fix PCS on to chassis

(Newbie) How to mount/fix PCBs on to chassis

Hi guys,

It's my first time trying to put my PCBs into a chassis. I know this has probably been discussed here, but I was lost in the search results.

Can anyone please share some tips or links on how to do that? My chassis has no hole drilled on the bottom panel. I also need to "paste" the amp to the side of the chassis, which is external heat sinks.

Thanks in advance.
 
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For the most appropriate and correct advice, post some photos to show what you are trying to mount.

Basically putting Tom's Modulus 86 x2 (Modulus-86: DIY 65W power amplifier achieving -120dB (0.0001%) THD – Neurochrome), power 86 x1 and a toroidal transformer into an aluminum chassis with heat sinks on the side. I am still waiting for the parts so no legit picture from me yet.\

The chassis will be similar to the one I uploaded here but I am still shopping around.

some chassis.png
 
I would get a couple short standoffs, which would be used between the two holes in the front of the amp board and the bottom of the chassis.
In a pinch, I've even used a few nuts instead of a short standoff.
You need to see what size screw fits through the board holes. In the US, it would likely be a #4 or #6, not sure if you guys up north use metric?

Standoffs should be positioned so that the amp ic can be bolted directly into the heatsink. I would drill the chassis holes a little large, so you have a little play to position the board.
Will make it easier to bolt it all together in the end.

You will need to drill a hole in the heatsink to use to attach the amp ic to it. If the ic has a plastic back, you don't need any insulation between it and the heatsink, otherwise you need heat conductive insulator.
I would make a tapped hole in the heatsink, so I could just screw into the hole. If you don't want to tap the hole, you can use a nut and bolt, just make sure the hole is between fins.

There are toroid mounting kits which are basically a big bolt and a big washer which will securely mount it to the chassis.
 
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Vovk Z

Member
2011-10-30 10:32 pm
Kyiv
Large things (like a power transformer) of cause drilled and bolted (screwed) to the case.
For all other small things I use plastic or metal stand-off spacers (usually, like on the second line of the photo):
attachment.php

For thin metal, I'll use female-female spacer and screw (like 6th on the photo).
For thick plastic, I use male-female ones (like 5th or 7th one) and make screw-thread (usually M3, 2.4-2.5mm hole) in the case.
 

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Vovk Z

Member
2011-10-30 10:32 pm
Kyiv
I don't know about that epoxy thermal glue. I know that these nylon standoff spacers, unfortunately, usually don't "take" a glue. Maybe there are exist some of them made of another type of plastic, which is glued ok. But usually they are nylon ones - they don't glued. :(
 
You really want to screw in the amp IC into the heatsink, asking for trouble if you try to do otherwise.

The diyaudiostore, and I'm sure other places, sell heatsinks with predrilled holes. But you will pay a premium that that. Or I'm sure you can find a local machine shop to do it.

But if you want to learn to build amps or other diy audio stuff, drilling holes is a necessary skill.

You also really need to bolt down the transformer. It will be big and heavy, trying to glue it down is really not a good idea.