Questions about PSU's

[pyrre]

I am making an ATX connector into a cable to use atx psu with amiga 500.

But i am a bit confused with the piouts.
+5V, +12V, -12V and ground i have sorted out.
HOWEVER
i am struggling with the shield connection.
is left untouched the amiga sound suffers badly
if connected to ground i get horisontal lines when ever cpu is doing anything. and strange artifacts on the screen....

What to do? how do i connect the shield cable properly?

[pyrre]

Hmm, I just grounded mine without issues.

Cheap ATX supplies can be noisy... as usually a PC motherboard handles a lot of the smoothing.

yea... makes sense... there are very few components to smooth out any noise...

Then again... i had issues with the sidecar and buddha... turns out major problems was dirty edge connectors and one of the zorro slots in the sidecar being faulty....

the cf cards booted just fine under uae. bot not in the A500 before i swapped the zorro slot... now it boots just like it has never done anything but...

however... the artifacts and the horizontal lines are still there...
snd i dont know how to "get them away"....

at least i got to backup the cf cards in uae

[pyrre]

The A500 schematic I looked at has the DC gnd and the shield gnd tied together. If you have an external powered audio speaker system plug into a different outlet than the computer it can cause a gnd loop which can cause your problem.

When i start a game. scorched tanks V.85 the psu screams like it is dying....

is there any way to reduse or remove the noise?
would soldering the shield to the psu case do any difference?

[pyrre]

Maddi made a psu hack, not atx brick though: https://www.youtube.com/watch?v=TTSoVmBKXbM

Hmmmmm... interesting
I was aiming to put to use one of those pico psu's inside my amiga 500 powerbrick.
I have desolderd an ATX powersocket from a dead atx MB and soldered the amiga power cable to the atx socket. and it works wery nice. (apart from the noice, though)
if i can put one of those picos there and get rid of the noice... id be happy....

i even put a svitch to the power on leads on the socket.

[pyrre]

Drewlio77 did a real nice brick transplant here.....

http://amigaworld.net/modules/newbb/viewtopic.php?topic_id=41790&forum=25

Nice work. but im a bit worried that 65W is shortcomming of running a derringer, buddha, cd-rom and a zip drive....

[pyrre]

Not available yet, but coming: https://amigakit.amiga.store/catalog/product_info.php?products_id=866

That looks really interesting