exxos's Atari, Amiga & retro forum

jwd wrote: 09 Nov 2022 09:48 Seems ok, obviously need a different connector end which isn't a problem but more to the point its built with retro care in mind.
Does anyone have any reservations on the above for a Falcon?

mrbombermillzy wrote: 09 Nov 2022 10:40 EDIT: Here's one that will work with the F030, although it's not the thinnest: https://www.checkmate1500plus.com/Products.aspx?id=379

frank.lukas wrote: 09 Nov 2022 13:25 Why not repair the original Falcon power supply? It's a good power supply.

Some notes on power supplies
Compared to a typical PC, Amigas use very little power. An unexpanded
Amiga 1200 uses less than 10W for example, and with an ‘030 CPU and
hard drive added to the system the power consumption is still most likely
less than 15W. PC power supplies tend to be marketed on their maximum
power output capacity, as this is critical for today’s power-hungry CPUs
and GPUs. However, their design typically also has a minimum power
draw requirement, which is a minimum amount of current that is needed
to flow in order to properly regulate their output. Many power supplies
will shut down if they try to start without the minimum required load
(in this case, the PSU will run for a second or two before shutting itself
down), but some – especially cheaper models – will allow their output to
vary and drift, potentially damaging the Amiga.
Minimum load conditions aren’t often published in the specifications of a
PSU, but they can sometimes be found in the technical data sheet if one
is provided. As a rule of thumb, the minimum load requirement is lower
for power supplies with a lower maximum output – 100W is likely to be
more than enough for any Amiga setup. Good quality PSUs will also tend
to have a lower minimum load requirement than poor quality units. A
PSU should be selected that has a minimum load requirement which can
be met by the Amiga and its peripherals.
In addition, the PSU picture is further complicated by the fact that
PSUs generally have a main output rail, to which all the other rails are
secondary, and which is the rail for which the minimum load is most
important. This used to be the 5V rail, which was the most heavily used
Section 26
98 | User manual version 2.0
Rail 15 Ohm 10 Ohm 5 Ohm 2 Ohm
3.3V 0.22A / 0.73W 0.33A / 1.1W 0.66A / 2.2W 1.65A / 5.4W
5V 0.33A / 1.67W 0.5A / 2.5W 1A / 5W 2.5A / 12.5W
12V 0.8A / 9.6W 1.2A / 14W 2.4A / 28.8W 6A / 72W
rail in the past, and is the most heavily used rail in the Amiga. But in
more recent times, PSUs instead have used the 3.3V rail as their main
output, which the Amiga doesn’t use and therefore doesn’t provide
any load at all to meet the minimum loading requirements. Even more
recently, to cope with the huge concentrations of power required in
CPUs and GPUs, the 12V rail has become the main output, with PCs then
converting this supply to lower voltages locally for whatever parts need
it. The Amiga uses small amounts of 12V power, which in combination
with extra peripherals like mechanical hard drives and fans may or may
not meet the supply’s minimum load requirements. Using the 12V rail as
the main power source for the computer has meant that the 5V rail has
been relegated to much lesser duties, and as a result its capacity has
been reduced in modern supplies. There should still be plenty available
for Amiga use, but it’s something to bear in mind – any PSU that offers
less than 4 or 5A on the 5V rail might cause problems on a heavily
expanded setup

jwd wrote: 09 Nov 2022 16:08 ...or am i being too paranoid here ?

exxos wrote: 09 Nov 2022 16:13 IIRC the falcon pulled 2 amps on the 5v rail. Maybe 100mA on the 12v. Did document it somewhere by think those are about correct.