PSU Heatsinks

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neilbaldwin
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PSU Heatsinks

Post by neilbaldwin »

I'll be shortly building the power supply for my DIY synth using the PSU-2 PCB. In the build documentation it suggests that mounting on a metal back plate gives enough heat dispersion without adding heatsinks.

I haven't yet quite decided on where the PSU is going to be housed/mounted so I was wondering if anyone has suggestions/pictures/ideas of this PSU built with heatsinks in a non-metal housing?

Thanks
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jbi
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Post by jbi »

The front panel for the PSU includes fixing holes for the PCB and power transistors but to make sure there was a big enough heatsink I mounted the PCB on insulated pillars with the transistors attached directly to the rear panel of my case. The case is wood, but the back panel is a sheet of 3mm aluminium. If it gets too hot, then there really is a problem. Don't forget to use a mica (or similar) washer between the transistor and heatsink together with a smear of heatsink compound to help heat transmission.
Cablebasher
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Re: PSU Heatsinks

Post by Cablebasher »

Hey guys

I am just starting my PSU version 1 issue 3 build (I know, old boards) and have a question.

If I am making a wooden case and therefore can’t attach the power transistors to a metal panel, do I just install them vertically on the pcb and attach some heat sinks?

Thanks as always
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Synthbuilder
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Re: PSU Heatsinks

Post by Synthbuilder »

Cablebasher wrote: Tue Oct 26, 2021 1:05 pm... do I just install them vertically on the pcb and attach some heat sinks?
It depends on how much current you intend to draw from the power supply and your AC input voltage. If you are planning to take anything like the 500mA from a PA20, you'll need to put those transistors on a substantial bit of metal otherwise it'll get too hot. Even a 4U 19" 3mm thick panel gets warm.

Standard clip-on heatsinks won't be good enough. You can fit the transistors remotely from the PSU PCB - although I wouldn't recommend any further than 150mm to keep the wire lengths to a minimum. The transistors can then be mounted on a large extruded aluminium heatsink mounted to the rear of the cabinet. As to the type of the heatsink it's difficult to say - but generally these things are going to be big if you wish to keep the transistors cool.
Cablebasher
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Re: PSU Heatsinks

Post by Cablebasher »

Ah I see…

In which case I will put a metal Panel in the back (instead of wood) and attach the power supply to that.

Better safe than sorry.
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eggpie
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Re: PSU Heatsinks

Post by eggpie »

I had to go the same route with my walnut case I had made. If you use eBay, there are sellers who supply aluminium panels and will even cut them to exactly the size you specify. Works really well. Mine is 900x300mm and only gets warm to the touch. Hope this helps.
Tom.
IMG_3406.jpeg
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eggpie
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Re: PSU Heatsinks

Post by eggpie »

PS. The panel is 3mm thick. Each of the two PSUs can supply just over 1A pos and 1.4A neg. They run about 18 modules each, comfortably.
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eggpie
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Re: PSU Heatsinks

Post by eggpie »

Sorry, 900x300mm should be 900x540mm.
Cablebasher
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Re: PSU Heatsinks

Post by Cablebasher »

Nice work.

I have ordered a 5U blank panel from allmetalparts

I will attach it to the back of my wooden case with makerbeam and then attach the power supply to that

Thanks for all the help and advice guys
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