RPSU question

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four_corners
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RPSU question

Post by four_corners »

I'm about to start building an SRE330 (very excited!), and had a quick RPSU question about the advantages of using a split output line lump versus a normal single phase wall wart.

In the US, the yamaha ps-20 seems to be around 60-70 dollars with shipping, so I started looking to just using one of these Jameco 16 VAC, 1amp wall wart instead...

https://www.jameco.com/z/ADU160100Z5401 ... 00108.html

Would someone be able to fill me in on the functional difference between something like that and the Yamaha PS-20?


I also came across a 3rd party "Console Mixer Power Supply" on eBay that seems like it might work, as it uses the same 3 pin connector and says "output: AC17V 600mA 20VA".

https://www.ebay.com/itm/115512618210?m ... media=COPY

Maybe I should just go for that instead as it is fairly affordable at $24. Seems to only output 600mA, but that should be enough for the SRE330 coming from one of these split output supplies right? It is only the single phase ones that needs at least 650mA (from what I gather from the build doc).

Thanks for the help!
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Synthbuilder
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Re: RPSU question

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four_corners wrote: Fri Jan 06, 2023 1:02 amIn the US, the yamaha ps-20 seems to be around 60-70 dollars with shipping
They've got really expensive of late, which is a real shame because they are a good choice when making a safe power supply.

... I started looking to just using one of these Jameco 16 VAC, 1amp wall wart instead.

https://www.jameco.com/z/ADU160100Z5401 ... 00108.html
That would work just fine for the SRE330. The SRE330 needs about 0.65A to work when used with a single phase supply, and this 1A one should have no problem in driving the SRE330.

Would someone be able to fill me in on the functional difference between something like that and the Yamaha PS-20?
The wallwart is a single phase supply. This is good for units that have a single rail power supply inside (eg. 0 and +15V), and also units that have a dual (split) rail supply inside (eg. -15, 0V, +15V) so long as the current taken by each rail is roughly the same. The SRE330 takes around +225mA and -180mA from the +15V and -15V rails respectively. This should be close enough not to cause a problem with the wallwart. I wouldn't want to drive a modular synth with such a power supply since they typically draw down significantly more from the positive rail.

The Yamaha power supply (and their clones) are proper three terminal supplies so can be used to supply dual rail supplies with no need to consider whether one rail is taking more than than the other. The maximum current draw still applies though.

I also came across a 3rd party "Console Mixer Power Supply" on eBay that seems like it might work, as it uses the same 3 pin connector and says "output: AC17V 600mA 20VA".

https://www.ebay.com/itm/115512618210?m ... media=COPY
This is a PA20 clone. It should work just fine.

The only issue I have with the various clones out there is their conformation to class II regulations. That is, just how good is their double insulation? It's probably fine, but the Yamaha one will have been properly tested.
four_corners
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Re: RPSU question

Post by four_corners »

Synthbuilder wrote: Fri Jan 06, 2023 4:35 am This is a PA20 clone. It should work just fine.

The only issue I have with the various clones out there is their conformation to class II regulations. That is, just how good is their double insulation? It's probably fine, but the Yamaha one will have been properly tested.
Thanks for all the great information (as usual) Tony! I'll try out the PA20 clone first and see how that goes.
four_corners
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Re: RPSU question

Post by four_corners »

Quick question Tony (or anyone that uses a PA20).

I'm still waiting for my PA20 to arrive, so I cant measure it myself, but I'm having trouble figuring out the correct size male plug to buy for the RPSU.

I found 2 different size 3 pin connectors, but not sure which is correct.
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Re: RPSU question

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four_corners wrote: Sun Jan 15, 2023 11:42 pmI found 2 different size 3 pin connectors, but not sure which is correct.
It's the bigger one of those two.
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Re: RPSU question

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Synthbuilder wrote: Mon Jan 16, 2023 5:07 am
four_corners wrote: Sun Jan 15, 2023 11:42 pmI found 2 different size 3 pin connectors, but not sure which is correct.
It's the bigger one of those two.
Just realized you sent me one with the PCBs, oops!
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Re: RPSU question

Post by four_corners »

I have another quick RPSU question.

If an aluminum shim is used for the regulators, wouldn't you not need to drill through the case? I would assume that an aluminum shim is enough of a heatsink for both regulators, and you can just countersink the holes in the shim and screw the regulators only to the shim. Obviously you'd still need to isolate the regulators with the insulation pad as the shim is touching on the inside of the case.

Just seems like it would be easier to deal with pcb alignment without having the regulators physically screwed to the case.
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Re: RPSU question

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four_corners wrote: Tue Jan 24, 2023 2:47 pmI would assume that an aluminum shim is enough of a heatsink for both regulators...
The heatsink is the case. The shim is needed if the case thickness is not sufficient to fit the mounting screws and other hardware. You don't need a shim if your case is made from a thick aluminium. The shim on its own would not be sufficient to keep the regulators cool.
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