Atari TT / MegaSTE ATX-PSU adapter

[Steve]

Hi all,

Recently Rodolphe was kind enough to send me some of his Pico-TT adapter PCBs. Today I built a few units for various people and took some photos for this guide.

Rodolph kindly uploaded his Eagle files to Atari Forum. I have re-uploaded them here for convenience.

PicoPSU_24.zip

The board itself

PicoPSU-MSTE-24.png

* Here is the original PSU that you will need to remove, the attached connectors and cables will need to be de-soldered (Motherboard connector and fdd/hdd molex connectors)

PXL_20201026_160207034.jpg

* Start by unsoldering the large blocks of cables, I put my iron at 377 degrees, added some fresh solder and waited a while, once it was all molten I tugged on the cables and they fell through.

PXL_20201026_160959043.jpg

* Like so:

PXL_20201026_161122626.jpg

* We will use the original switch and can also use the AC socket for the Pico power plug with some modification

PXL_20201026_162341549.jpg

* Here I have removed the pins from the AC socket

PXL_20201026_164107822.jpg

* By drilling a hole in the centre I can mount the Pico power plug

PXL_20201026_164938492.jpg

* Here we have the power plug mounted

PXL_20201026_165727719.jpg

* Here you need to wire the power switch to the bottom end of the unit

PXL_20201026_170124552.jpg

* Here you can see the motherboard connector wires line up perfectly with the terminals, secure them like this. You cannot go wrong as the order is exactly the same as the connector wire order. Orange, Yellow, Blue, 4x GND, White, 3x Red.
Atari TT mobo connector voltages:
+5 (PowerGood Line), X, +12v, -12v, Gnd, Gnd, Gnd, Gnd, -5v, +5v, +5v, +5v

PXL_20201026_171519907.jpg

* On the other side you have 5v, gnd, gnd, 12v for your HDD and floppy. The red cables are 5v and the yellow are 12v.

PXL_20201026_172705787.jpg

* Here is an overview of everything wired up

PXL_20201026_173637250.jpg

* Testing the unit on regular graphics

PXL_20201026_180440412.jpg

* Testing the unit using NOVA graphics

PXL_20201026_181059781.jpg

[Steve]

I have some spare boards made up, PM me if you'd like one.

FYI the unit basically runs cold and the -5v regulator barely gets warm. I'm running my fan on silent now. Of course this is the adapter only, you will need your own PicoPSU and power brick. PicoPSUs can vary in quality so I recommend you use a good unit, here is a great review that @Atarian Computing told me about:

http://www.jonnyguru.com/modules.php?na ... y&reid=207

And BIG THANK YOU to Rodolphe for making this possible!

PXL_20201026_153048534.jpg

[frank.lukas]

Why ?

The original Power Supply are very good.

[Steve]

Why ?

The original Power Supply are very good.

* Because they do not last forever.
* Some people are Musicians and require a silent TT/MSTE.
* Someone might not have a PSU at all.
(I currently have a Musician & someone without a PSU who need them)

[Cosmic Puppet]

Quality work as usual. 8-)

[rpineau]

I made these for the exact reason Steve is pointing : I got a TT .. without PSU .. this was the easy way to get it powered.
Now I'm glad it can help other people in similar situation.
Rodolphe

[czietz]

FYI the unit basically runs cold and the -5v regulator barely gets warm.

Did you test it in TT mono resolution, too? The main load on the -5 V rail are the ECL ICs that do TT high-res mono. They draw a lot of current so that any linear regulator powered from -12 V invariably gets quite hot.

[Steve]

@czietz
Thanks I didn't think of testing ECL, I thought the Mach64 in the ISA bus would have tested the negative rail enough? What do you think

[czietz]

Thanks I didn't think of testing ECL, I thought the Mach64 in the ISA bus would have tested the negative rail enough? What do you think

Does the Mach64 even use the -5 V rail? Many ISA graphic cards don't -- which is good because the VMEbus does not provide -5 V. (Meaning that you have to run an extra wire to the ISA slot if you're using a card that needs -5 V.)

[Steve]

Okay, I wasn't sure - I'll make sure to test it under ECL mode too!