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Old 10 September 2020, 13:05   #1
Ulysses13
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Floppy disk PicoPSU inside an A1200

Hi guys.

I'd like to get a Pico PSU unit working with my A1200 and have it inside the case, using a nice neat 12v wallplug and no more external power brick!

Between this and HDMI output I'm hoping to just have two simple cables out the back instead of the mass of crap that currently lives there.

They have various models of the PicoPSU:

https://www.mini-box.com/DC-DC

I'm not all that clued up about wattages/voltages etc etc, but I know that I need to ensure my A1200 has sufficient juice for any upgrades.

At the moment I am running:

IDE SD Card adapter
8Mb Fast RAM expansion + FPU + RTC
Indivision AGA MK3 Scandoubler/FlickerFixer

And in the future I'd like to add a couple of USB ports.

At the moment, I'm not feeling the need for any kind of acceleration, but in the future, who knows...

So my A1200 isn't a crazy setup, quite modest really, but more elaborate than stock obviously.

So, my question is, do I just buy the maximum wattage PicoPSU (160) or do I need to look at a specific one?

Any guidance appreciated, especially if anyone has actually tried this themselves!
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Old 10 September 2020, 14:12   #2
demolition
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The current on 5V is what's important. If it can supply 4.5A like the beefy original PSUs, it will be plenty. The small original PSUs are only rated for 2.5A and most Amigas run fine with that, so 4.5A will provide plenty of margin.

Edit: Looking closer at the specs, even the smallest 80W version is rated for 6A (7A peak) so I would consider that as plenty. Notice that a constant 6A would require a fan, but your Amiga will only use half that so there shouldn't be a problem.
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Old 10 September 2020, 14:19   #3
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Get the PicoPSU-80, it's quite enough for Amiga use.
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Old 10 September 2020, 14:23   #4
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Get the PicoPSU-80, it's quite enough for Amiga use.
And beware of the cheap Chinese knockoffs. They usually don't work very good if at all.
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Old 10 September 2020, 14:38   #5
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Yes, on ebay I would expect most of them to be knockoffs and definitely if they're significantly cheaper than the originals. If you're not in the US, look for an official reseller here:
https://www.mini-box.com/site/resellers.html
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Old 10 September 2020, 22:55   #6
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I got one inside my A600 with a big enough power switch. This is PicoPSU-80 (with Ian Stedman's Big Box ATX adaptor). Works like a treat
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Old 11 September 2020, 15:13   #7
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Quote:
Originally Posted by demolition View Post
The current on 5V is what's important. If it can supply 4.5A like the beefy original PSUs, it will be plenty. The small original PSUs are only rated for 2.5A and most Amigas run fine with that, so 4.5A will provide plenty of margin.
Side track, -ish: The experience me and a some friends had back in the 90's was that although the 4.5A PSU initially as expected could handle more load than the 2.5A PSU but over relatively short periods (weeks, months perhaps?) with a large load (say an A1200 or A500 with a 68030 accelerator and a hard disk) the newer light weight primary switched 4.5A PSU would get weaker and weaker while the older heavy secondary switched 2.5A PSU would just work, work and work, but it was best to have the CPU kind of floating in the air to somewhat improve air flow as the PSU would get super hot.

I havn't taken any measurements on what consumption an A1200 witn 030 and hard disk has, and also haven't measured at what actual maximum current draw the old 2.5A PSU stops outputting a good regulated 5V, but my conclusion is that the rating on the original Amiga PSUs aren't that usable to determine what rating a replacement would need to have. To be sure you'd have measure current consumption at full load. (I assume that 100% cpu load and having the disk seek while the floppy is running and seeking would probably be the case that consumes as much current as possible although if it's a 3.5" hard disk a bunch of that consumption would be irrelevant as it would come from the 12V supply).

As the replacements discussed here have a far larger rating than the different Amiga PSUs they whould be fine anyway.
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Old 11 September 2020, 15:32   #8
Lord Aga
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You can help your Amiga load by using a CF card vs a mechanical drive tho.
Those little buggers use very little power.
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Old 11 September 2020, 18:40   #9
Ulysses13
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I'm having trouble finding a good guide or tutorial for this mod, but the pieces are falling into place gradually.

The PicoPSU has a 2.5mm power input jack, so what sort of ac adapter would be needed for that? If it is one of those wall-socket ones like a phone charger style then that's nice and tidy, but would it need to be one of the laptop style ones, basically a new brick between the wall plug and the Amiga? That's a shame if I'm trading one brick for another...
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Old 11 September 2020, 19:00   #10
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It takes a 12V supply and I would say at least rated for 2.5A. You might be able to find one that is contained in a wall connector but it will be somewhat larger than your average cell phone charger.

Perhaps you can find one from a dead Netgear router?
https://i.ebayimg.com/images/g/MpEAA...Vt/s-l1600.jpg
There are also some 3.5A models:
https://i.ebayimg.com/images/g/rSgAA...HA/s-l1600.jpg
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Old 12 September 2020, 05:53   #11
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12v and 2.5Amps then you are going for a 30W PSU.... way below your needs.
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Old 12 September 2020, 07:42   #12
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Originally Posted by seb132 View Post
12v and 2.5Amps then you are going for a 30W PSU.... way below your needs.
My Amigas use less than 20W when running so I think it should be sufficient as long as there are no power hungry stuff installed like 040/060/PPC cards.
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