Amiga A4000T Underpowered: Full Toaster - Flyer Setup

[crazyegg]

Hi All,

The power supply on my recently acquired Escom A4000T just died.

While it probably should not be too surprising since this a retro computer after all.

However what is surprising me is the "smallish" size of the stock power supply. My unit says 250W with 26A on the 5V and 9A on the 12V rails. While this is more than enough to run a standard A4000T setup, I don't think its enough for a full blown Toaster-Flyer setup.

For example, the Quantum Atlas SCSI hard drive draws 2.9A at peak on startup according to the spec sheet. Since the Flyer setup takes 3 SCSI drives that is already drawing the full 9A of the stock power supply.

This is not even including the CD-ROM, Zorro slots, motherboard, and the A3640 which will make the 12V rail overloaded!

Am I reading this correct? After all, the A4000T was designed to run the Toaster - Flyer right?

If so, what minimum size power supply is needed to PROPERLY run such a beast? Thanks!

Regards,
ed...

 

[Ed.D]

Motors pull more current when they start up and this reduces when they are at running speed. You may be able to reduce/offset the large startup current if you have jumpers on your hard drives which allow for delayed spin up. If you have your operating system on one drive I would not set this jumper on that drive but would set it on your other drives.

 

[bdb]

Why not ask the opposite question, "How large of a new AT PSU can I find the days?"

The answer is as much as 450W, but 400W PSU's are more available. AT PSU's are an identical replacement for the standard 230/250W that the A4000T shipped with.

 

[Firthy2002]

Why not ask the opposite question, "How large of a new AT PSU can I find the days?"

The answer is as much as 450W, but 400W PSU's are more available. AT PSU's are an identical replacement for the standard 230/250W that the A4000T shipped with.

Could you not just get an ATX PSU and one of those AT adapters?

 

[crazyegg]

Hi All,

Thank you for all your replys!

The ATX-AT adapter sounds like a good option. I never thought about it before.

A few questions though:

• Can I buy any ATX-AT adapter or do I need a specific one?
• Are there any dangers or disadvantages for using this kind of setup?
• How will my Amiga turn on? These adapters do not apear to have an on/off switch?

Regards,
ed...

 

[bdb]

The AT PSU's cost the same as an ATX + adapter, are exactly the same size at the original A4000T PSU and have the power out socket to turn on your monitor with the computer.

Amigakit's adapters have a on-off switch but are half the price of the PSU.

 

[Tahoe]

Am I reading this correct? After all, the A4000T was designed to run the Toaster - Flyer right?

Nope. Commodore never designed anything for third parties; apart from that it seems the Flyer was released in 1994, the year Commodore went bust. the A4000T had already been designed by that time, and had already been in production, be it a small run of 200 units.

The flyer was actually supposed to house the Audio/Video drives externally instead of internally, using the so called "Octopus" cable and a box called the "Drive-In".

 

[geminister]

No, ATX PSUs don't work with A4000T's as they usually don't supply -5v. I've tried it. It's easier to find a new AT PSU than a ATX PSU that supplies -5v.

Why not ask the opposite question, "How large of a new AT PSU can I find the days?"

The answer is as much as 450W, but 400W PSU's are more available. AT PSU's are an identical replacement for the standard 230/250W that the A4000T shipped with.

Could you not just get an ATX PSU and one of those AT adapters?

 

[bdb]

That was my point, too. The AT PSU's cost in the 3 - 5 large 16" cheese pizza range for one rated 300 - 400 Watts and are identical is size, screw holes, external power cord socket (for the monitor), and don't need an adapter.

The Amiga Technologies engineers really produced a good product with the A4000T -- maybe why I own two. They are spacious, easy to work on (without cutting your hands), have no easily breakable plastic parts -- except the plastic front door I removed to save it from suicide. No special case, PSU, drive rails, and such. The two posterior I/O cables are tricky when pulling the drive cage, but you can by-pass replacing the coin battery with an AT battery off board, cut and move the SCSI terminator to open up four (2 X 9-pin and 2 X 25-pin p) ports, use the extra 6" above the PSU for special projects, and pull drives by just holding in two tabs.

 

[BLTCON0]

+1 for the AT PSU.
Also as has frequently been pointed out - ATX PSUs are generally optimised for stability on the 3.3V rail which isn't used in the Amiga anyway.

 

[bdb]

Er, well some folks use the +3 Volts for PCI Radeon cards. Granted not a feature needed at the time of design nor use.

 

[crazyegg]

Hi All,

I did a bit more research with your tips and found that all of the ATX supplies now have ample current on the +5 and +12 rails.

Regardless, I found a brand new AT power supply at Newegg and just ordered it. It is only 250W though so maybe I will have to adjust my startup spin delay on my SCSI Flyer setup. Thanks!

Regards,
ed...

 

[geminister]

Hi All,

I did a bit more research with your tips and found that all of the ATX supplies now have ample current on the +5 and +12 rails.

Regardless, I found a brand new AT power supply at Newegg and just ordered it. It is only 250W though so maybe I will have to adjust my startup spin delay on my SCSI Flyer setup. Thanks!

Regards,
ed...

Sure, +5 and +12 is fine, but the A4000T needs -5 too...

 

[bdb]

And a standard AT PSU is a standard AT PSU -- it has all the rails the A4000T needs; or at least the 2 A4000Ts I own.

I checked and the Newegg one for 1.5 16" cheese pizzas is 300W. A 450W will run 2.5 that or over 3 16" cheese pizzas