I could also use some help about buying an ATX replacement along with the adapter from amigakit.
It seems that 12,5 cm wide PSU might fit the A4000 case screws but would leave space underneath, like this one:
How to fit it securily?
And more important, would the PSU actually turn itself off with the switch from amigakit?
I do not like those ATX PSU that are always on.
I ahae not owned a PC tower since the AT era with good old power switch, only laptops, and i am not confotable with the ATX standard.
Not from Europe, I'm afraid. You need to ask the locals.
Just remember those newest ATX24 connector units needs around 15 to 20% of the 3.3V rail maximum rate to work properly or they will not regulate the other voltages.
Be warned, although a high wattage simple resistor will do the trick ( 0.47 Ohm x 50W soldered directly inside the PSU to keep the resistor cold).
On this specific PSU you need a charge of 4A on the 3.3V rail to stabilize the other voltages, so this means a 0.82 Ohm resistor (good luck finding one!) per 10W dissipation at least.
If you don't find one, use TWO 1 Ohm /10W resistors IN PARALLEL to draw ~ 6.6A from the rail. This will suffice to force the PSU to regulate the other voltage rails to safe Amiga operation.
Just don't use much Zorro cards on this Amiga because the relatively weak +5V rail.
Now, if you can measure the A4000 PSU height & width you may find something better who fits on the available space.
Well, unfortunately, i won't be able to add any resistor myself. For such a work, i can only count on Cosmos, who lives 400 km far from me. Sending him all my parts has already drained so much money from my pocket in shipping cost that i could buy another A4000.
I need to find a good enough PSU at once or find someone to build a better one for me.
The A4000 is rather limited in slots, unlike the A2000. Would 4 zorro boards and 2 ISA boards be too much?
Could you explain a bit more the concept of charge on the 3,3V? I do not understand what it means. Is the 3,3V used on the amiga?
The 3.3V is not used by the Amiga at all unless you are using a hacked Meditator 4000Di and a Radeon92xx.
In order to make ATX stabilizes ALL their voltages, some charge (consumption) must be put on the 3.3V wires. That's where the pair of 1 Ohm x 10W resistor goes. Without they the 3.3V will not have any consumption, rendering the whole power brick VOLTAGES unstable.
But of course you can add those resistors directly on the ATX connector, just notice the pair will heat a lot. You also must make they secure in the socket.
Four Zorro boards and two ISA will consume a lot of juice, prefer to find something with at least 28A on the +5V rail for secure operation.
No, it does not. You must solder the resistors inside the ATX PSU by removing the 3.3V wires (orange) and solder the resistors instead, with the other resistor leads to ground (black wires).
Nothing really hard to do if you have a simple potent soldering iron (60W is preferred) and some solder.
Ok, i have finally bought from AmigaCenter France an original A4000D PSU. I hope it won't be too noisy.
Thanks rkauer for the advices.
In the meantime, i will look without hurry for a good suitable ATX PSU for the future
Ok, i have finally bought from AmigaCenter France an original A4000D PSU. I hope it won't be too noisy.
Thanks rkauer for the advices.
In the meantime, i will look without hurry for a good suitable ATX PSU for the future
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