Microbotics Starboard 2 for A500 HELP

[JLF65]

The A500 model NEEDS the power. I used one for a time. Make sure you hook it up to the correct source or you'll fry your expensive and irreplaceable board. In fact, the A500 NEEDS more power than the stock supply can supply or things like accelerator cards won't work. When I was running my A500, I used a 125 W supply with it.

[JLF65]

Metalguy66 wrote:

BuzzBrain wrote:

I asume you use the orginal external power for the GVP devices?
So, the SCSI/IDE disk and the 8mb memory use own power?

You assume wrong.. EVERYTHING on all 3 systems runs off of the A500 power supply. I dont use the GVP external power supplies at all.. In fact, I dont even know where they are.. Ive never used them. The stock A500 PSU runs everything just fine.. and for hours on end... and has for years..

Somehow I don't believe you. Your "stock" A500 PSU is probably a custom one. I had/still have an A500 with the TRUE stock PSU, and it could BARELY power the 512K belly memory expansion and one external floppy. NOTHING else. Period. End of discussion. New and more powerful PSUs for the A500 did a brisk business in those days as the stock supply was good for nothing. Wherever you got your A500 from, the dealer almost certainly swapped your PSU for something more powerful.

The stock supply for the A1200 was even worse. Go to any Amiga magazine or any Amiga site and you'll see the same thing - those stock supplies couldn't power virtually anything at all. It's why things like the GVP had their own supply in the first place. They wouldn't have put it on there if it wasn't necessary.

[JLF65]

Metalguy66 wrote:
I dont think anyone is "mistaken". I just think weve had different experiences..

For example: And A500 rev3/rev5 board has 16 (256kx1)ram chips just to make 512k. This pulls significantly more current than 4 (256kx4) chips on a rev 6a (or later board). You throw in an early model A501 expansion, and guess what.. ANOTHER 16 chips.. Thats 32 ram chips instead of 8 on the later models.

Also, look at the size difference in the stepper motors on the early floppy drives (like the A1010 and early "all metal" mechs used in the first A500s & A1011s) versus the new "plastic" ones used in the later A500s. Floppy drives are consntantly starting & stopping spindles and "grinding away" at the disks moving the head steppers.. Also remember with MFM, it cant start & stop one drive spindle independantly, it does both simulatneously.

Also, look at early hardisk controllers that used all DIP package logic, and tons of it, versus the newer designs that only had one or two small surface mount package custom chips. (eg. the A590 versus the GVP A500 HD+/8)... big difference..

Its also possible that commodore "beefed up" the PSUs in later A500s after so many people b!tched about them burning up in earlier units.

I would expect the A1200/A600 motherboards to be significantly less power-hungry than an A500 due to the fact that almost everything had been replaced with newer, smaller, surface-mount components.

So you see, there's quite a few factors here. I believe him when he says he had problems. Ive heard others say the same thing. Im just glad my particular combinations work with a single stock PSU. Id hate to have YET ANOTHER power cord to deal with, or some "hacked PC unit" looking PSU..

Now that all makes more sense. I got one of the early A500s, so the RAM was just like you described. Floppies in '89 or so were definitely a far cry from one in the middle to late '90s. The A500 manual itself said to not use more than the RAM expansion and ONE floppy without replacing the PSU... which I one of the first things I did, getting a Phoenix PSU, which had a handy on/off switch as well.  :-D

I eventually chopped up one of my A500 PSUs for the cable, which I attached to a 125 W PSU. That was able to drive my A500 with one of those funky 512K extra chip RAM + 2.5 MB of slow RAM expansion cards (Fatter Agnus required), 68030 with 8MB, two external floppies, and a Slingshot with an EMPLANT and HYDRA ethernet cards. That wouldn't work without TWICE the power of an A500 stock PSU.  8-)