Installing the exxos improved power supply 110V

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Installing the exxos improved power supply 110V

Post by TheNameOfTheGame » Sun Sep 15, 2019 2:51 am

I was going to put this here originally but ended up posting at atari-forum due to seeing the ominous "lock" symbol on the hardware thread here and not remembering the sub-forums were open. :hide:
Upon being set straight on the issue :chairsmack: (thanks exxos), I wanted to leave a small write-up here regarding my experience with the installation of the nice improved power supply I purchased
from the exxos web shop.

Just today, and due to the threat of imminent power supply failure with my STE I decided to finally install the exxos improved power supply I bought a couple years ago (I know, I know...procrastination :lol:)

You see, my old, well-used power supply was suddenly emitting a strange smell after warming up...sort of like burning electronics. :fire: Although it still worked, it was time to change it out.

Here is a picture of the old power supply with the odoriferous offender:
step-0_psu-modified.png (747 KiB) Viewed 276 times
Upon review of a side-by-side comparison between the original power supply and exxos' version, I know which one I'd rather have. :D
You can see on the old metal mounting bracket that I left the original switch and mains plug. For me it was simpler and
quicker to do it that way. It was less soldering and fuss and the original connections already had insulating covers at the terminals.
For the hot (black) and neutral (white) wire on the original psu pcb, I heated the solder connection from the underside of the
board while gently pulling on the wires to lift them up and out.
step-0b_newpsu.png (675.7 KiB) Viewed 276 times
Next, I made sure to test the fit of the new psu on the metal bracket as a 'dry run'. This test showed a couple of points that needed consideration.
As can be seen in the picture below, leaving the original mains plug and power switch made for a tight fit with the new psu board. I also elected
to leave the original circular ferrite choke where it was at the on/off power switch. However, even with these conditions, it was not too cramped
as there was enough space to place the new board.
step-1b_newpsufit.png (630.61 KiB) Viewed 276 times
Additionally, regarding the fit, the mounting holes didn't line up completely evenly as seen in the picture below. The board was a little longer than
my mounting bracket. There are probably variations in the size of the brackets due to manufacturing batches when originally sourced. Still, this
wasn't insurmountable. By loosening the screws fastening the opposite edge (not seen) and pushing back slightly on the board, there was a little play there
that allowed all 4 screws to be fastened. As a last task on the fitting test, I marked the center of the voltage regulator hole on the mounting bracket.
Marking the center of the hole is a prerequisite for the next step. It needs to be marked accurately. Although the regulator is not pictured, it is
illustrated in exxos' installation guide.
step-1c-newpsuholes.png (472.06 KiB) Viewed 276 times
Now the metal mounting bracket needed to be prepped. The original plastic insulating sheet was removed leaving the glue residue which attached it
to the bracket. This required a little force to pull off. It was glued down pretty good. The insulating sheet needs to be removed so that one of the voltage regulators
can be screwed to the bracket in order to use it as a heat sink to dissipate heat. Exxos kindly supplied the screw and nut in the kit with the power supply.
Keep in mind that the thermal paste needed between the regulator and the metal bracket was not included and must be purchased separately. I chose to use
arctic silver as the paste which I bought online. So that the regulator can be attached to the metal bracket, a hold needs to be drilled through the metal.
Using the center mark I made at the end of the last step I used a 2.78mm drill bit to make the hole. Exxos recommends 3mm in his install guide, but 2.78mm was
close enough and is all I had. Here you can see the bracket after the hole has been drilled. Unfortunately as you can also see, the dried glue from the removed
insulating sheet is smack-dab all around the hole. This residue needs to be removed so that good contact can be made between the regulator and the metal bracket.
step-2_drillhole.png (689.76 KiB) Viewed 276 times
To remove the glue down to bare metal, I used a heavy grit sanding block of the type found in any home improvement store. There are many ways to accomplish
the task, but it must be cleaned down to the metal. Also, a fine metal file was used to remove any burs around the edge of the drilled hole. The edge of the hole
should be smooth and flat. Here is the result after prepping the metal.
step-2b_cleanhole.png (376.73 KiB) Viewed 276 times
So far, so good. Now I had to turn my attention to the power connection on the new power supply. More to the point, the old power connector and wires from the
original psu should be removed and soldered to the new power unit. Once again, I heated the connections on the solder or bottom side of the board and gently
pulled the wires out when the solder was viscous. Alternately you could just snip the wires off from the board. Because of the way the wires were made by Atari,
they had a crimp connector on the ends so I ended up having to snip the crimps off and then strip some insulation from the wires which reduced the length of them.
Because I had less wire to work with, I had to remove the original ferrite choke. Here is the connector removed from the old board.
step-3_mainboardconnector.png (645.92 KiB) Viewed 276 times
And here it is soldered into the new psu. I placed the wires in from the top one at a time and soldered from underneath. This gives a neater look to the job as opposed
to soldering from the top (component) side.
step-3b_mainboardconnectorb.png (860.28 KiB) Viewed 276 times
Moving forward, the next thing to do was prep the metal bracket in anticipation of mounting the improved psu. Specifically, the thermal paste must be applied to the
spot where the voltage regulator will be screwed down. This allows the heat to evenly and efficiently dissipate through the metal mass of the mounting bracket. Without
the paste, the regulator would almost certainly burn up, so this is important to do. One thing about the arctic silver, it is very tacky and gets everywhere if you aren't
careful. As you might deduce from the picture below, I would get low marks for neatness on this step. I did try, though. :lol:
step-4_mountpsuprep.png (789.77 KiB) Viewed 276 times
Following completion of the previous step, everything is ready to finally attach the exxos psu to the mounting bracket. Here is the final result. The 4 mounting screws
are attached, the voltage regulator is screwed down to the metal bracket and the hot and neutral wires are connected to the mains plug and power switch. For the voltage
regulator, the screw comes up through the bottom of the bracket and the nut is attached to the threads that protrude. It should be noted that there is not much space to
grab the small nut with a nut driver or socket ratchet. At least for my socket set the socket driver was too thick to get down around the nut due to the body of the regulator
being so close. To compensate, I held the head of the screw from underneath with a phillips screwdriver and used needle nose pliers to slowly tighten the nut on the top.
This was a little slower than having a nut driver, but it only took a minute or two. For the hot and neutral wires, I used wire nuts to connect them to the mains plug and
power switch wires respectively. The proper connections are detailed in exxos' install guide and here in the forum. Since this power supply is 110V, two wires fed the transformer
on each incoming rail. Exxos had pre-twisted these wires to help keep them together which worked well. A note about wire nuts and power. It is recommended to tape
each wire nut to the wires after testing and making sure everything is working. This is not shown in the picture below, but can be seen in a later image after the voltage
had been tested and the computer reassembled.
step-4b_newpsumounted.png (903.63 KiB) Viewed 276 times
That's it. The improved power supply is ready at this stage to be tested. I would recommend testing this outside of the case before risking damage to the Atari. The unit
can be tested without a load. However, caution must be exercised, since live mains or line voltage will be present and carries risk of electrocution. Be careful! Below are
the results of the measurements. Both the 5V and 12V rails demonstrate solid, stable voltage within very good tolerance. Nice.
step-5b_5vmeasure.png (635.76 KiB) Viewed 276 times
step-5_12vmeasure.png (665.36 KiB) Viewed 276 times
Now that I had assurance the unit was assembled and working correctly, it just needed to be put into the computer and everything reassembled. There is not much to say regarding
this step, as it is straightforward. Note the electrical tape on the wire nuts as mentioned in a previous step. A couple of black tie-wraps were used to keep the wiring neat.
step-6b_reassembleb.png (512.84 KiB) Viewed 276 times
It was a little surprising to me that the original psu cover still fit. The installation guide exxos provides mentions that the cover may need to be left off due to space restrictions
after fitting the new psu. I would guess the factors involving whether the cover will fit back on or not would be how low-profile the wiring was kept at the top of the transformer
and/or if the wires could be tucked-in or kept tight at the back behind the power board.
step-6c_reassemblec.png (506.62 KiB) Viewed 276 times
Now my Atari STE has a brand new power supply which should provide me many years of trouble-free operation. Thanks to exxos for producing the unit. The construction is high
quality and the installation is straight forward and generally trouble-free with just a few points of consideration which is to be expected with all the different models of STs in
the field. I would say the installation would be rated a low-to-medium difficulty. There's not much there to cause trouble for anyone with even a small modicum of soldering or hardware
installation experience. Cheers!
step-6d_reassembled.png (553.02 KiB) Viewed 276 times

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Re: Installing the exxos improved power supply 110V

Post by exxos » Sun Sep 15, 2019 4:59 am


Just want to mention that this is the old style PSU board which I think hasn't been sold for a year or so now. So there is no need to drill holes etc with the later versions.

I do also now sell new PSU connectors which I recommend as I and others have found, the origional ones sometimes cause a bad connection.

Great work! :thumbup:
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter All my hardware guides - mods - games - STOS - All my hardware mods for sale - Please help support by making a purchase.

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