Please help! A1200 w/ ATX PSU problem

[ruina]

Hey everyone,
My amiga 1200 arrived last night, but i couldnt get the power supply that i bought to power the system up.

It's an ATX v2 PSU (i.e. the 24-pin version). I followed the pinouts on the amiga atx guide here:

http://www.ianstedman.co.uk/Amiga/amiga_hacks/Amiga_Power_supplies/body_amiga_power_supplies.html

The pinouts for the amiga side were also written in marker on the bottom of the A1200 case.

And I followed the 24pin ATX pinouts here:

http://pinouts.ru/Power/atx_v2_pinout.shtml

On the PSU I hooked pin 4 red (+5v), pin 12 yellow (+12v), pin 14 blue (-12v), and pin 16 green (PS-ON) to the relevant parts on the amiga power cable.

I connected both the shield and ground to pin 16 green, because the bottom of the amiga said "ZW" (whatever that means) was the ground wire, while the atx guide said "BL" (black, the only remaining color cable) was the ground.

I went through numerous variations on the above scheme, but all of them failed.

The PSU fan starts moving for just a millisecond the moment I plug the cable into the amiga. Basically, it seems the PSU won't turn on (I don't get any LED's or smoke from the amiga, and the PSU fan ends up not turning).

Is this because ATX v2 requires more of a power load to turn on? Am I missing something?

I got the ATX psu for free new from a store, there's nothing wrong with it.. But since I got it free, I don't mind going out to the electronics district and getting a basic AT psu instead. Does AT have the same load requirements or is it easier to get the AT type going?

Any help would be greatly appreciated. I haven't used amiga in 7 years and am excited to get back to it. So, if I get some word maybe I can go on my lunchbreak today to get what I need.

Thanks in advance!

[rkauer]

Green pin of ATX MUST BE CONNECTED TOGHETER WITH GROUND! in order to the PSU turns on.

 If you want to use ATX PSU like a regular Amiga brick, put a switch in the PSU and use green and a black wire to turn on/off.

If the PSU turns on only for a while, it means you have a short-circuit on one rail. Normally, Amiga's shield need +5V connected (not a permanent one, BTW). Said that, logically you short the +5V and ground via Amiga's shield wire.:crazy:

 ATX permanent +5V don't be needed to plug anywhere, so don't bother to plug it (simply cut it out). The same for 3.3V (orange) wires.

[ruina]

Thanks for your reply rkauer.

"I connected both the shield and ground to pin 16 green."

You can see I connected PS-ON to ground.

The ATX PSU has a on/off switch on it already, so I don't need an extra switch or playing with wires.

When I put the switch to ON, The PSU only turns on for 0.000001 seconds. The amiga doesn't even turn on.

" Normally, Amiga's shield need +5V connected (not a permanent one, BTW). Said that, logically you short the +5V and ground via Amiga's shield wire. ATX permanent +5V don't be needed to plug anywhere, so don't bother to plug it (simply cut it out)."

I'm not sure what the above means. Do you know if it's easier to use AT psu instead of ATX? Thanks again.

[Computolio]

    Not only is it easier, it's also way cheaper.

[ruina]

Well, I went to the electronics area during lunch but there were no AT psu's to be found. I grabbed a multimeter instead to check continuity and make sure I have the right pins. Maybe I'll try to put a load on the psu with some extra drives to see if it'll work. I have no idea.

Any other help would be nice. Thanks.

[McVenco]

ruina wrote:

The pinouts for the amiga side were also written in marker on the bottom of the A1200 case.

I connected both the shield and ground to pin 16 green, because the bottom of the amiga said "ZW" (whatever that means) was the ground wire, while the atx guide said "BL" (black, the only remaining color cable) was the ground.

Since I was the previous owner I can probably shed some light here. When I bought this A1200 from the first (dutch) owner the pinouts were already there. I think he wrote the abbreviations for the dutch names of colours on there, so they would probably mean as such:

ZW = zwart (dutch for black)
BL = blauw (dutch for blue)

I don't know if there's a blue cable at all in there, but the black cable really should be the "ZW" one AFAIK.

Glad to hear the A1200 arrived in good shape :-)

[ruina]

Okay, well..

I finally got the wire situation figured out.

But now, the amiga boots up (hdd spins up, etc.) however after 3 seconds or so, the PSU shuts down.

I thought maybe it didnt have enough load so I threw in an accel card and pcmcia card, etc. But same problem.

I disconnected the amiga and just hooked an external dvd-rw drive up to one of the PSU's drive cables, again it shut off after 3 seconds.

So it seems the PSU (It's BTX/ATX2.x) is being the problem, but I'm not sure at all what it could be.

I came so close to the amiga booting :boohoo:

Can anyone help?

[Ross1]

Do you have the switch hooked up to pins 13 and 14 on the ATX wire block? You need to have wires 13 and 14 tied together or a switch across them in order for the PSU to be powered up.

[HellCoder]

Perhaps you made the same mistake I did by using the red wireline from the HD connector. You should use the red wire line from the motherboard connector as that can drive more power!
(If that is what you did though)

[ruina]

Yeah, I have them although on the new ATX that would be pin 15 and 16 as can be seen here

http://pinouts.ru/Power/atx_v2_pinout.shtml

[ruina]

Yeah, I'm taking +5v red wire from the main mobo connector.

Even without the amiga plugged in, the PSU is shutting off after 3 seconds. It's a brand new 350 watt atx psu so it should have no problem... except that I'm not doing something to keep it on.

[Delta]

I'm no specialist in the new ATX pinout but you mentionned the PSU turns off after a few seconds.  Have you tried just connecting pin 16 (PS_ON) to ground to turn the PSU "ON" then disconnecting it so it should stay powered.  

AFAIK you just need to have the power on pin shorted to ground for a millisecond to turn on an ATX power supply?  

Tought it might work.....?

[ruina]

I was doing everything right with the ATX but it just wouldn't stay on, so I bought a cheap AT supply and got the amiga up and running in 5 minutes.