Modding a short ST for PicoPSU

[Steve]

Hey guys,

I did this PSU mod today on my short ST. Fairly straight forward stuff. I'm putting a NOVA graphics adapter and perhaps other upgrades in this guy and noticed the original PSU wasn't quite powerful enough, so I got this really good quality Pico floating about that I wanted to use (was rated top amongst all other picos on a reputable review site)

I jumpered PS_ON to GND so the Pico would turn on as soon as it's shown input voltage, scraped the underside of the motherboard 5v switch traces and patched it to always send 5v, then used the redundant original switch to enable/disable power to the Pico.

I mounted the Pico with double sided thermal tape on to the modulator base area for good heat dissipation, I also desoldered the original power input socket and fitted a modular power plug in its place, where the Pico feeds in its voltages.

The Picos barrel input jack pokes out the modulator hole in the case, secured on to the motherboard with clear araldite.

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[PhilC]

Thats an incredibly small PSU @Steve. What's the rating and cost of that?

[Steve]

@PhilC I bought it about two years ago (originally to use on my Falcon) from the official Pico box website in USA. Was quite pricey from memory, I think it cost almost £100 shipped. I think it was 90w. I'll see if I can find the details tomorrow.

[Steve]

Thats an incredibly small PSU @Steve. What's the rating and cost of that?

Found it Phil, it's 120 watt:
https://www.mini-box.com/PicoPSU-120-WI ... wer-supply

It was rated as the best quality Pico on a famous ATX PSU review site which funnily enough I can't remember the name of lol

[exxos]

Thats an incredibly small PSU @Steve. What's the rating and cost of that?

Found it Phil, it's 120 watt:
https://www.mini-box.com/PicoPSU-120-WI ... wer-supply

It was rated as the best quality Pico on a famous ATX PSU review site which funnily enough I can't remember the name of lol

Looks like one I reviewed a while back https://www.exxosforum.co.uk/atari/last/pico/index.htm

[Steve]

@exxos @PhilC I found the review I was talking about:
https://web.archive.org/web/20170906101 ... y&reid=207

Apparently, according to this reviewer, the actual power brick has a large effect on each PicoPSU so he tested each Pico with different bricks to see the differences. I bought an FSP 19v brick as they used in the review since it performed best.

Now let's see how the PicoPSU 120-WI-25 works with 19V input using the FSP power brick:

Efficiency: Efficiency is consistently over 80% thanks to the fact that the FSP power brick has fantastic efficiency to begin with. There's still quite a bit of power loss here, so I can't still give it a 10. Score here is only going to be 9.5.

Voltage regulation: The +12V only dropped .3%. +5V only dropped 1.2%. Fantastic and worth a score of 10.

Ripple suppression: Once again, there's no ripple on the +3.3V and +5V, but also the +12V is cleaned up significantly. Score here is a 10.