A590 when connected stops A500 from powering up .

[Kakaboy]

Hi fellas,

So as a follow on to my recent AT PSU mod for A500 , I decided to include the power for the A590 HDD .

Now my issue is they both power on seperately but when connected the A590 powres on but the A500 does not .

I can disconnect the A590 with power left in and they both power on RED LED and the A500 has usual kickstart screen .

I am fairly certain I have wired the A590 correctly :

Red - Red +5v
Black - Black GND
Brown - Yellow +12v
Rest - not connected

The AT PSU is 200W and the A590 & A500 only need 145W together . So its deffinately not underpowered .

I forgot to mention when i disconnect the power from the A590 and connected to A500 it still does the same thing , which makes me think theres something wrong with the A590 ?

Any ideas Guys ?

Should I start looking for another A590 ?

BTW I have new A590 roms coming , if it happens to be roms .

Thanks in advance

[Loedown]

A590 won't power up unless it gets a power sense from the A500, absolutely 100% sure this is in some way your issue.

Usual way of A590 is that even when you turn its supply on, it will not start unless the A500 does, you may have to incorporate a relay into your design so that the A590 has power earlier than the A500.

Latest firmware for A590 is 7.0 AFAIK, it enables you to use bigger SCSI drives upto 4Gb.

[Kakaboy]

Originally Posted by Loedown

A590 won't power up unless it gets a power sense from the A500, absolutely 100% sure this is in some way your issue.

Usual way of A590 is that even when you turn its supply on, it will not start unless the A500 does, you may have to incorporate a relay into your design so that the A590 has power earlier than the A500.

Latest firmware for A590 is 7.0 AFAIK, it enables you to use bigger SCSI drives upto 4Gb.

There is a power sense wire from the A590 cable that I didnt wire up , I read other threads that it wasent necessary . But I think they had seperate PSU's .

When they are both connected the A590 has red led and the A500 has nothing .

[Loedown]

The A590 won't start without a power sense signal from the A500, I think it's +5V from memory and that's what's stopping the A500 from starting.

The sequence of events you need is;

1. Power up the A500 with power sense to a relay.
2. Relay controls +5 / + 12 to A590

You need a snubber diode on the relay to stop back EMF, you also need to find out where the A500 gets it power sense from to see that the line can power the relay without melting a trace off the A500. I'm going to do exactly the same thing and power the A500 / A590 combo from a single AT PSU, I just haven't done it yet. I would also suggest using a TTL style relay to drive a bigger one they only need around 20 - 25mA to trip, +5 / +12 will be around 2A for the A590, needs to be a DPST relay.

 
  +5 o------o--->
              |  o------A590 +5
              |
+12  o------o--->
                 o------A590 +12

[Kakaboy]

Ok so the power sense +5v wire from A590 needs to be connected to a relay which powers on the +5 & +12v for the A590 .
I assume the A500 sends power to the A590 thru its expansion port as the original psu was dead as a door nail but A590 still worked.
Im not electrically minded I only know the absolute basics .
thanks for you help btw .

[Loedown]

Originally Posted by Kakaboy

Ok so the power sense +5v wire from A590 needs to be connected to a relay which powers on the +5 & +12v for the A590 .
I assume the A500 sends power to the A590 thru its expansion port as the original psu was dead as a door nail but A590 still worked.
Im not electrically minded I only know the absolute basics .
thanks for you help btw .

If you know the absolute basics I highly recommend you stop here, before you blow the absolute shit out of your A590 and or your A500

[Kakaboy]

Originally Posted by Loedown

If you know the absolute basics I highly recommend you stop here, before you blow the absolute shit out of your A590 and or your A500

Thanks mate ,

I will wait for a more info .

[Loedown]

Originally Posted by Kakaboy

Thanks mate ,

I will wait for a more info .

It's not massively high on my priority list, but when I get around to it I can send you the relevent information.