A590 harddisk distortion

[Speelgoedmannetje]

Hello all,
The display of my Amiga 500 had some distortion in it. As things worsened over time, I thought it was something nearby that was distorting it. But I found out now that the harddrive is to blame, and I think it's primarily the psu that is to blame, because the harddrive itself runs perfectly, no errors/slowdowns whatsoever. Has any one has any experience with this?

[danbeaver]

What exactly is the "distortion?" Is this seen on a CRT (electromagnetic) or a TFT/LCD/LED?  Does it improve the further you move the PSU away?  Have you checked the voltages of your PSU?

"So many questions, so little time."

[Oldsmobile_Mike]

Not sure what you mean by "distortion", but here's a couple suggestions for you if you suspect the A590 PSU is causing you trouble:

1 - Convert your A590 to use motherboard power:
http://members.iinet.net.au/~davem2/overclock/a500hd.html

However if you're going to do this I'd recommend getting one of those MechWare SCSI card readers or a SCSI-to-IDE bridge plus an IDE-to-CF adapter, so you you can use low-power CF cards.

2 - Get this adapter from AmigaKit and an old PC PSU:
http://amigakit.leamancomputing.com/catalog/product_info.php?cPath=39&products_id=901

3 - Find a replacement PSU on ebay or Amibay.  Good luck!  

[Speelgoedmannetje]

What exactly is the "distortion?" Is this seen on a CRT (electromagnetic) or a TFT/LCD/LED?  Does it improve the further you move the PSU away?  Have you checked the voltages of your PSU?

"So many questions, so little time."

I've moved the psu far away from the good ol' 1084S monitor but the picture did not improve at all. The distortion shows dark and bright horizontal stripes in the picture.
I'll still have to check the voltages.

[Speelgoedmannetje]

Not sure what you mean by "distortion", but here's a couple suggestions for you if you suspect the A590 PSU is causing you trouble:

1 - Convert your A590 to use motherboard power:
http://members.iinet.net.au/~davem2/overclock/a500hd.html

However if you're going to do this I'd recommend getting one of those MechWare SCSI card readers or a SCSI-to-IDE bridge plus an IDE-to-CF adapter, so you you can use low-power CF cards.

Hm, that sounds like a nice idea..

2 - Get this adapter from AmigaKit and an old PC PSU:
http://amigakit.leamancomputing.com/catalog/product_info.php?cPath=39&products_id=901

Well, I looked into that but I don't think that's really suitable for the A590. The A590 psu has a 'power sense' line and this one does not. It would mean the A590 is continuously switched on instead of being switched on/off by the Amiga. I wonder if I can make an ATX psu react to that 'power sense' line.

[Tenacious]

Hello all,
The display of my Amiga 500 had some distortion in it. As things worsened over time, I thought it was something nearby that was distorting it. But I found out now that the harddrive is to blame, and I think it's primarily the psu that is to blame, because the harddrive itself runs perfectly, no errors/slowdowns whatsoever. Has any one has any experience with this?

Is the video distortion there when you remove the A590 from the system (A500 alone)?

Have you added some kind of acceleration to the A500/A590 setup?

[Oldsmobile_Mike]

Well, I looked into that but I don't think that's really suitable for the A590. The A590 psu has a 'power sense' line and this one does not. It would mean the A590 is continuously switched on instead of being switched on/off by the Amiga. I wonder if I can make an ATX psu react to that 'power sense' line.

Still not really clear what you mean by "distortion", but if you have your entire system hooked up to a power strip you can just turn it all on or off that way - no need to fuss with the "power sense" line.  

[Speelgoedmannetje]

Is the video distortion there when you remove the A590 from the system (A500 alone)?

The distortion is gone completely if I remove the A590. Even if I have the psu turned on near the monitor.

Have you added some kind of acceleration to the A500/A590 setup?

Well, I got the standard Commodore A501 memory upgrade (of which I recently replaced the battery)

[Speelgoedmannetje]

Still not really clear what you mean by "distortion"

Eh, noise in the picture (not in sound though, as far as I can hear it).

but if you have your entire system hooked up to a power strip you can just turn it all on or off that way - no need to fuss with the "power sense" line.  

Aw well, I just want it to be working neat again.
It's my precious, you know?

[Oldsmobile_Mike]

Eh, noise in the picture (not in sound though, as far as I can hear it).

So just to be clear, you're getting distortion in your picture when you've got the PSU for the A590 plugged in, and it doesn't matter how far away you set the PSU from the monitor, you still get it?  What type of monitor and video connection are you using?  Since the A590 sits pretty close to the Denise chip inside the A500 case, I wonder if it could be somewhere in the power interface circuitry of the A590 that's bleeding over into the A500?  Does your system have all of it's metal RF shielding intact?

As a test I'd recommend getting that adapter from AmigaKit and a spare PC PSU.  It's cheap and will help you with the troubleshooting process, even if it's not the perfect solution.  I totally understand about "my precious", haha!  :banana:

[Oldsmobile_Mike]

Oh, look what random picture just came up in the gallery link:

http://www.amiga.org/gallery/index.php?n=2223

[Amiwest]

distortion could be caused by several things.
RFI -http://en.wikipedia.org/wiki/Radio-frequency_interference
and using Ferrite_bead is used to suppress it. - http://en.wikipedia.org/wiki/Ferrite_bead
but by moving the pwr supply away not helping it is more an indication of a ground loop.
http://en.wikipedia.org/wiki/Ground_loop_%28electricity%29
Plugging computer, hard drive and monitor to the same outlet should cure it if that is what is causing the problem.

[Tenacious]

The distortion is gone completely if I remove the A590. Even if I have the psu turned on near the monitor.
Well, I got the standard Commodore A501 memory upgrade (of which I recently replaced the battery)

It is my belief that the Commodore sidecars were not as tolerant and robust as the GVPs and Supras.  I never found an A590, but, I have used several A570s.  They don't like anything playing with the CPU timing.  The A590 may be as intolerant.  Your A501 should not be an issue at all.

Off the cuff, here are some things to try:
Make certain the ground and shield connections between the A500 and A590 are tight and shiny where everything slides together.  The grounds of the A500 and A590 should be the same (no voltage between them)!
Consider re-installing the fingered shield bracket that is screwed across the top of the edge connector, if it has been removed.
With everything powered, carefully check the power rails of the A500 and A590.  DVMs are inexpensive today.
Power all PSUs from the same power strip (per Amiwest)
Consider an older beefier PC PSU and make new cables to it with Mec's square Amiga connectors.  I did this.

[Speelgoedmannetje]

distortion could be caused by several things.
RFI -http://en.wikipedia.org/wiki/Radio-frequency_interference
and using Ferrite_bead is used to suppress it. - http://en.wikipedia.org/wiki/Ferrite_bead
but by moving the pwr supply away not helping it is more an indication of a ground loop.
http://en.wikipedia.org/wiki/Ground_loop_%28electricity%29
Plugging computer, hard drive and monitor to the same outlet should cure it if that is what is causing the problem.

Yes a ground loop is what it looks like, but it has not always been there, it gradually occurred, sometimes, sometimes not, sometimes faint, but eventually continuously. Maybe some thing that made it short circuit?

Btw. I've had some difficulty connecting the A590 a while ago. It did spin up and then it began to spin fast, and locked up the Amiga (black screen, no guru), I had to clean the edge connector and seat it really well to make it work again.