My A500+ Project

[sim085]

pyrre wrote:
I would not use two PSUs for one computer...

Why? Is it for the space they take or there is something more to it? Such as it is bad to first switch off one device and then the other!

pyrre wrote:
I would rather modify one to power both the computer and the Hdd.

At the moment I was trying to avoid doing this since my soldering skills are practically none.

However still; even if with one PSU then is it just a question of switching off the PSU or I have to follow some steps to switch the Amiga off? I do not feel right just switching off the PSU since it feels as if I am cutting the electricity from the hard drive all of a sudden and thus potentially breaking it.

[rkauer]

 The use of just one PSU is highly recommended. IF you have to use two PSU, then the better thing is put the the two in a switched distributor and simply turn it off instead the PSUs.

 The Amiga is projected to do this, and always be. Only crap like M$ computers need "press to shutdown".

[Lockon_15]

Long time ago, you had to perform "HDD heads parking" procedure, before killing power, in order to prevent heads ramming onto rotating disk surface.  Not sure, but i.e. A590 install floppy could still have little utility for that purpose.

Anyway, your SCSI drive, if larger than 300Mb should have autopark actuator servo, meaning you can switch off PSU anytime except while some larger chunk data is being written accross disk (like moving files between disk partitions).

Don't get me literally as a 100% secure source, but somehow I guess GVP should be powered first, before A500. A500 maps GVP RAM in autoconfigured memory address space and that means RAM should be powered before A500 Kickstart routines start. On the second note, powering GVP should spin-up SCSI HDD motor and thus harddrive starts prepared for controller SCSI commands when they start rolling.

Powering off may be in reverse order - first A500, then GVP.

Let's wait for other opinions.

[Lockon_15]

@sim085

...And if decide to substitute big, noisy, hot, power hungry SCSI HDD with the feature-opposite CompactFlash card, you can wire GVP controller to drain power from A500 side bus expansion, instead of your current GVP PSU.

That would put you in win-win solution: single PSU and single power-on/off cycle.

[sim085]

Thanks for the replies. I am very conservative and was not planning to change the hard drive ... mostly since I just bought the thing and seems it is working as should

I am glad to hear that the hard drive will auto lock once the power is turned off. I thought I should have to lock the hard drive first in some way or another.

BTW - The hard drive has a switch on top of it. If I am not wrong this is to determine if I want to play using the floppy disks or else start the workbench from the hard drive. If so, couldn't I just turn this switch to 'Game' and then restart the amiga and only after that I switch off everything? Or changing this when the hard drive is running is considered a bad thing?

[pyrre]

     
pyrre wrote: I would not use two PSUs for one computer...  

Why? Is it for the space they take or there is something more to it? Such as it is bad to first switch off one device and then the other!

Two psus, if not grounded in the same socket may cause electric "disturbance" (don have the correct English word for it). Current may interfere between the two psus and may in worst case damage or blow up your computer. If grounded correct this is not an issue. But i have blown a pc motherboard and a disk drive of such reasons...

To find out if you have a problem with "overspenning" (norwegians, please help translate) touch the two psus if you can feal the current flowing in your hand... Switch to one psu immediately before damaging something!

[sim085]

I have connected the two PSUs to a socket extention which in turn is connected to the same wall socket. This means that if I wanted I could just turn the wall socket off and all my Amiga (including hard drive) would also turn off. I am not doing so because I am afraid this would damage something. Feel safer to switch on/off everything step by step. However I guess if all my PSUs are connected to the same wall socket (through the socket extention) then I should not have the problem you mentioned - altough I will still test

[pyrre]

Connected in the same extension cord should mean they are grounded to each other. Meaning no current will flow between them. But measure it with a multimeter to be sure.

[Tenacious]

Switching both simultaneously with the power strip would probably be just fine. If you feel safer with a sequence, then switch the GVP ON first then the A500.  When powering OFF, the A500 should be switched OFF first, then GVP.

My 2 cents.

 

[A1260]

why would you buy/use a none grounded socket extension in the first place?... and you dont grab your moms 1970 socket extension and use that.. your dealing with computer equipment and 1 rule is ground everything to hell and back before usage.

[pyrre]

why would you buy/use a none grounded socket extension in the first place?... and you dont grab your moms 1970 socket extension and use that.. your dealing with computer equipment and 1 rule is ground everything to hell and back before usage.

Could no agree more.

[sim085]

I bought this socket extension a month ago so it is new! However I am no expert in electricity and therefore cannot know if it is grounded or not! I do not know if this is relevant but where I live (Malta) our electrical system is like that of the UK; this means we have a Neutral wire in every plug (even the socket extension I bought has one)

I would never use old equipment with my A500+; apart from my A500+ :-P :-)

[pyrre]

tree wires usually means a grounded socket. two wires for the current and the one for grounding.

[darksun9210]

the GVP was designed to use an external powersupply and all it probably drives is the hard disk itself. probably isolated from the A500's supply so that it doesn't cause floating earths, fluctuating voltages all all the other scare stories people have been saying on here. :lol:

basic rule of thumb.
turn on all extrnal devices first, then the amiga.
to turn off, switch off the amiga, then all external devices.

the switch on top of the GVP unit you have, is a disable  switch. some really old floppy games don't like the presence of extra fast memory, or a hard disk. so flick the switch, reboot, and the hard disk and memory isn't visable to the amiga anymore. switch it back, reboot, and you should be back to hard disk nivarna.

to be honest, it'll probably be one of the least used switches you'll ever own ;-)

[sim085]

Thanks people I'll follow the instructions

[Amike]

In the showroom of a1k.org you can find some interesting A500 projects. There is also an international section where you can post your questions about the projects.

http://www.a1k.org/forum/forumdisplay.php?f=14