Atari TT / MegaSTE ATX-PSU adapter

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Steve
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Atari TT / MegaSTE ATX-PSU adapter

Post by Steve » Mon Oct 26, 2020 8:26 pm

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
(52.81 KiB) Downloaded 24 times
The board itself
PicoPSU-MSTE-24.png
PicoPSU-MSTE-24.png (42.69 KiB) Viewed 998 times
* 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
PXL_20201026_160207034.jpg (400.51 KiB) Viewed 1019 times

* 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
PXL_20201026_160959043.jpg (331.42 KiB) Viewed 1019 times
* Like so:
PXL_20201026_161122626.jpg
PXL_20201026_161122626.jpg (370.67 KiB) Viewed 1019 times
* 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
PXL_20201026_162341549.jpg (242.72 KiB) Viewed 1019 times
* Here I have removed the pins from the AC socket
PXL_20201026_164107822.jpg
PXL_20201026_164107822.jpg (236.43 KiB) Viewed 1019 times
* By drilling a hole in the centre I can mount the Pico power plug
PXL_20201026_164938492.jpg
PXL_20201026_164938492.jpg (232.43 KiB) Viewed 1019 times
* Here we have the power plug mounted
PXL_20201026_165727719.jpg
PXL_20201026_165727719.jpg (312.28 KiB) Viewed 1019 times
* Here you need to wire the power switch to the bottom end of the unit
PXL_20201026_170124552.jpg
PXL_20201026_170124552.jpg (310 KiB) Viewed 1019 times
* 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
PXL_20201026_171519907.jpg (311.62 KiB) Viewed 1019 times
* 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
PXL_20201026_172705787.jpg (348.94 KiB) Viewed 1019 times
* Here is an overview of everything wired up
PXL_20201026_173637250.jpg
PXL_20201026_173637250.jpg (361.78 KiB) Viewed 1019 times
* Testing the unit on regular graphics
PXL_20201026_180440412.jpg
PXL_20201026_180440412.jpg (401.37 KiB) Viewed 1019 times
* Testing the unit using NOVA graphics
PXL_20201026_181059781.jpg
PXL_20201026_181059781.jpg (431.89 KiB) Viewed 1019 times
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Steve
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Re: Atari TT / MegaSTE ATX-PSU adapter

Post by Steve » Mon Oct 26, 2020 9:08 pm

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
PXL_20201026_153048534.jpg (263.56 KiB) Viewed 979 times
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frank.lukas
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Re: Atari TT / MegaSTE ATX-PSU adapter

Post by frank.lukas » Mon Oct 26, 2020 9:27 pm

Why ?

The original Power Supply are very good.

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Steve
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Re: Atari TT / MegaSTE ATX-PSU adapter

Post by Steve » Mon Oct 26, 2020 9:31 pm

frank.lukas wrote:
Mon Oct 26, 2020 9:27 pm
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)
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Re: Atari TT / MegaSTE ATX-PSU adapter

Post by Cosmic Puppet » Mon Oct 26, 2020 10:15 pm

Quality work as usual. 8-)
US Atari 520 STFM (C070523-001 REV.D1) 4MB Marpet Upgrade, TOS 1.04, EmuTOS 1.0, Ultrasatan, PP Driver, Original Floppy Disk Drive, NEC Multisync EA193Mi Monitor.

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Re: Atari TT / MegaSTE ATX-PSU adapter

Post by rpineau » Mon Oct 26, 2020 11:31 pm

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
Working ones : MegaSTE (68020) / TT030 / Falcon with AB040 & Eclipse / 1040STF
Need testing : Falcon with CT2

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Re: Atari TT / MegaSTE ATX-PSU adapter

Post by czietz » Tue Oct 27, 2020 7:29 am

Steve wrote:
Mon Oct 26, 2020 9:08 pm
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.

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Steve
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Re: Atari TT / MegaSTE ATX-PSU adapter

Post by Steve » Tue Oct 27, 2020 11:49 am

@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
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Re: Atari TT / MegaSTE ATX-PSU adapter

Post by czietz » Tue Oct 27, 2020 4:50 pm

Steve wrote:
Tue Oct 27, 2020 11:49 am
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.)

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Re: Atari TT / MegaSTE ATX-PSU adapter

Post by Steve » Tue Oct 27, 2020 6:44 pm

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