Can an A500 or 600 PSU power an A590?

[Merlin]

Hi, a bit of a technical question here. I have an A590 which I have been trying to get back into the land of the living. It came with a 20Mb XT IDE drive in it which was dead as a doornail.

I got hold of a 4Gb SCSI-II drive and 68-50 pin adapter and a 50 pin SCSI cable. I have rejumpered the A590 LED for SCSI operation.

It didn't have a PSU when I got it, so I re-wired a lightweight "brick" PSU from an A600 to use just the +5v, +12v, 0v wires and screen, wired to a 4 pin DIN plug to fit the A590.

So far, so good....but.....

The A590 doesn't power up; it doesn't matter if it's connected to an A500 or not - nada, zilch, bugger all etc.

I note that the A590 pinouts have a 'power sense' pin. Could this be what's missing from my cunning plan? Have i rewired a spare Amiga PSU in vain, as it needs the 'sense' wire to work?

[FOL]

Well according to the power pinout for the A590 it uses 4 pins. So cant see why it wouldnt work. Unless the Expansion port or PSU is faulty.

1 +5VDC
2 Ground for +5VDC
3 Ground for +12VDC
4 +12VDC

Did the PSU work on an A500 or A600 before you rewired it?

Originally Posted by Merlin

Hi, a bit of a technical question here. I have an A590 which I have been trying to get back into the land of the living. It came with a 20Mb XT IDE drive in it which was dead as a doornail.

I got hold of a 4Gb SCSI-II drive and 68-50 pin adapter and a 50 pin SCSI cable. I have rejumpered the A590 LED for SCSI operation.

It didn't have a PSU when I got it, so I re-wired a lightweight "brick" PSU from an A600 to use just the +5v, +12v, 0v wires and screen, wired to a 4 pin DIN plug to fit the A590.

So far, so good....but.....

The A590 doesn't power up; it doesn't matter if it's connected to an A500 or not - nada, zilch, bugger all etc.

I note that the A590 pinouts have a 'power sense' pin. Could this be what's missing from my cunning plan? Have i rewired a spare Amiga PSU in vain, as it needs the 'sense' wire to work?

[TheCorfiot]

Wait a mo..

Pin 3 is indeed Power sense & it connects internally in the A590 to Pin 6 of the 86Pin edge connector which connects to the A500.

From what i can tell at a quick glance it is not tied up by any other logic, at a wild guess I would say it is actually an output to the PSU to switch it on from standby when the A500 is powered up & this is sensed by pin 6 on the 86pin edge connector.

Melicious would you like the A590 Service manual..?

TC

Just checked the A500 Schematic too & pin 6 is +5V, I'm fairly confident I'm right.

[Merlin]

Hmm,

I got the diagram at pinouts.ru which stated

Pin 1 +5v (Red on Amiga PSU)
Pin 2 0v (Black on Amiga PSU)
Pin 3 +12v (Brown on Amiga PSU)
Pin 4 Power Sense - NC

The white -12v wire is taped off and not connected.

I haven't grounded pin 4, although I don't think that would make the difference. The PSU definitely worked before I modded the plug.

I have the A590 manual thanks, I was just hoping for a few pointers from the gurus on here as to what could be wrong.

I powered up the A590 before the A500+ I am using to test it, I assume that's the right way to do it. I've not connected the A500 to a TV, because I wanted to get a power up of the A590 first before I went any further. I have the lighter weight PSU on the A590 and a heavy one on the A500+.

[TheCorfiot]

Originally Posted by Merlin

Hmm,

I got the diagram at pinouts.ru which stated

Pin 1 +5v (Red on Amiga PSU)
Pin 2 0v (Black on Amiga PSU)
Pin 3 +12v (Brown on Amiga PSU)
Pin 4 Power Sense - NC

The white -12v wire is taped off and not connected.

I haven't grounded pin 4, although I don't think that would make the difference. The PSU definitely worked before I modded the plug.

I have the A590 manual thanks, I was just hoping for a few pointers from the gurus on here as to what could be wrong.

I powered up the A590 before the A500+ I am using to test it, I assume that's the right way to do it. I've not connected the A500 to a TV, because I wanted to get a power up of the A590 first before I went any further. I have the lighter weight PSU on the A590 and a heavy one on the A500+.

Merlin If you have the A590 Service manual Check your pinouts, the list above does not tie up with my manual, The std A600 PSU should cope fine. also in your case because your PSU is always on then not having the A500 connected should still start the A590 up.

TC

Don't Ground Pin3 / Power sense as it is being fed +5V from the A500 leave it unconnected.
You can double check +12 /+5 & Gnd by disconnecting the HD & using a meter to continuity check the rear Power connector against the HD power connector, also confirm the "sense / pin 3" which goes to pin6 on the 86pin edge connector.

[Merlin]

The diagram I got is wrong, I just checked the A590 service manual and it's wired differently.

I'll rewire it again properly tomorrow and try again. I presume the pinouts are looking at the connector on the back of the A590, i.e. the socket, and not looking at the pins inside the plug?

[FOL]

After finding the manual, I agree with TheCorfiot.

From the looks of it, the A500 supplies the other main voltage for the HDD. Would need to study it further to be sure.

Originally Posted by TheCorfiot

Merlin If you have the A590 Service manual Check your pinouts, the list above does not tie up with my manual, The std A600 PSU should cope fine. also in your case because your PSU is always on then not having the A500 connected should still start the A590 up.

TC

Don't Ground Pin3 / Power sense as it is being fed +5V from the A500 leave it unconnected.
You can double check +12 /+5 & Gnd by disconnecting the HD & using a meter to continuity check the rear Power connector against the HD power connector, also confirm the "sense / pin 3" which goes to pin6 on the 86pin edge connector.

[TheCorfiot]

Originally Posted by Merlin

The diagram I got is wrong, I just checked the A590 service manual and it's wired differently.

I'll rewire it again properly tomorrow and try again. I presume the pinouts are looking at the connector on the back of the A590, i.e. the socket, and not looking at the pins inside the plug?

See my previous post / edit, If you have a meter handy this will dispell all doubts. But ensure you leave sense unconnected you don't need it with your modded PSU, If you apply power to it you may damage your A500

TC

Notice on FOL's thumbnail,,, The schematic shows power sense as an output, ie direction of label.

BTW Thanks FOL

[FOL]

Originally Posted by Merlin

The diagram I got is wrong, I just checked the A590 service manual and it's wired differently.

I'll rewire it again properly tomorrow and try again. I presume the pinouts are looking at the connector on the back of the A590, i.e. the socket, and not looking at the pins inside the plug?

Normally, the plastic should be marked 1,2,3 & 4. Like the brick PSU's are. I would have said yes though, the way it is on the diragram is the same when you look directly at it.

[FOL]

Originally Posted by TheCorfiot

Notice on FOL's thumbnail,,, The schematic shows power sense as an output, ie direction of label.

Yep, proberly some type of feedback to the original PSU from the looks of it.

[Merlin]

Result! my A590 now powers up! Now all I have to do is set the SCSI ID's and attach the external SCSI CD-ROM drive that I have and the system should be good to go.

Thanks, guys....

[FOL]

Originally Posted by Merlin

Result! my A590 now powers up! Now all I have to do is set the SCSI ID's and attach the external SCSI CD-ROM drive that I have and the system should be good to go.

Thanks, guys....

Nice you got it working, . I remember my A590, I was 1 of the only kids in school who had 1. They used to bang on about floppies and I would say, bah dont need floppies for that adventure its all on my 20MB HDD.
Always came the reply "WOW, 20MB".

Just incase anyone else has this problem, can you explain what you done?

[Secret Vampire]

Regarding Power sense - while trying to get a nonfunctional a590 powered up I cracked the PSU open and had a look inside. The power sense wire goes to a relay on the PSU main board which switched the mains input on when the A500 is switched on - hence the lack of a switch on the 590 PSU.

Never did get the 590 to work though, I gave up on it after a short while (Intending to return when bored) since I got a GVP HD+8 with it, and that did work.

[TheCorfiot]

Originally Posted by Secret Vampire

Regarding Power sense - while trying to get a nonfunctional a590 powered up I cracked the PSU open and had a look inside. The power sense wire goes to a relay on the PSU main board which switched the mains input on when the A500 is switched on - hence the lack of a switch on the 590 PSU.

Never did get the 590 to work though, I gave up on it after a short while (Intending to return when bored) since I got a GVP HD+8 with it, and that did work.

So my Guess was spot on !!!

Merlin, put us out of our misery, What was the problem??

TC

[Merlin]

It was wiring....

I wired it as you suggested and as per the correct diagram (pin 3 not connected), switched on and the lights blinked. I then connected it to the A500+ and switched on and both powered up!! I now need to set the SCSI ID for the A590 controller and hard drive before I connect it to the CD-ROM which has it's own terminator fitted. It should all work swimmingly from here on in....

Pin 1 - Red (+5v)
Pin 2 - Black (0v)
Pin 3 - NC
Pin 4 - Brown (+12v)

White (-12v) - not connected

[TheCorfiot]

Excellent News Merlin, Glad to have been some help

TC

[FOL]

Originally Posted by TheCorfiot

Excellent News Merlin, Glad to have been some help

TC

Nice, now others can do the same, .

[Photon]

Yes it can, I've done it. Just get the pinout right.

[protek]

Used to have an A590 for which I had fabricated a cable to use an ATX PSU. The A590 powered up nicely but kept resetting intermittently. Imean you could hear the HD to make the spin cycle what it does during power-up. I then got an original A590 PSU and didn't have such problems since. Any ideas or was it just a bad soldering or such in the cable?

[TheCorfiot]

Originally Posted by protek

Used to have an A590 for which I had fabricated a cable to use an ATX PSU. The A590 powered up nicely but kept resetting intermittently. Imean you could hear the HD to make the spin cycle what it does during power-up. I then got an original A590 PSU and didn't have such problems since. Any ideas or was it just a bad soldering or such in the cable?

At a guess I would say the A590 was not providing sufficient load for the ATX PSU to stabilise properly( not enough current draw on +5V). Maybe if you had powered both A500 & A590 from the same PSU then the system would have been stable.

TC