X68000 Compact - example of a PSU integration and battery upgrade

Started by wild_potato, January 29, 2019, 11:22:10 PM

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I fixed the PSU of my x68k compact recently.
Anyway you've got enough resources with the tutorial pages https://gamesx.com/wiki/doku.php?id=x68000:how_to_open_x68000_compact and https://nfggames.com/nfg/x68repair/ but maybe you'll lose time with some components you should buy. The adventure worked for me, but it is really tight and I feel lucky. So I hope this could help someone with this basic PSU failure.

I've chosen the smallest standard ATX I've found, an FSP-180, around 50â,¬.
It is a Slim factor PSU, and 180W is much but ok. Here is what I bought for my Compact:
- A standard Slim PSU
- An 74LS04 or so
- A small prototype board
- A (european) AC cable like this I will reuse the male part
- Optionaly a ML2032 battery
- ...and a button battery holder for instance this one

And you'll need adhesive, a soldering station, a metal saw, a Dremel like cutting tool, and a few hours.

Step 1 : simplify the new ATX PSU
The PSU fits just fine in the chassis but you will figure out that you need to cut the back side (where there is the fan), and all useless wires. Each milimetter is necessary to fit the fan, so I'm not sure an other PSU than the FSP I tried will fit.
You have to remove the standard DC connector, I did not figure out how to reuse it on the x68K

Remove the useless cables, and cut the two lateral iron part the most you can or it won't fit

As you can see the PSU can't fit at all for now, and the fan is not well centered compared to original fan output.
For this PSU model, the right side on the photo can be cut and you can move the fan a bit to the right, perfect  :D

Step 2 : dremel the chassis
The PSU fits in width if you cut the lateral reinforcement you can see on the picture.
I did not cut the 1-2mm plastic on the bottom. But you can if you want more space for future cable as you'll need to pass them on the top cover.

Remove the lateral plastic reinforcmentuntil the Slim-PSU fits perfectly.
I would cut the small plastic left on the bottom to have 1mm vertical more space

Optional step : upgrade the battery,
I bought a ML2032 3V Lithium battery and a button battery holder. It is standard and cheep but I did not figured out how to connect properly on the board. I soldered extension pins and added wires on the top.
Add heat resistant adhesive to make sure pins won't disconnect and you can connect the holder on the top where there is space.

The battery is now attached to the chassis

Step 3 : Solder the signal inverter chip
Follow the tutorial, you will then have just necessary space where the 220V comes. I did not find a more adaptated box than a Frisk box (peppermint ;D ) to put the small chip and wires in, it looks safer once in the box.

Cut your cables for the necessary length and put the 74LS04 on a protoboard

Keep enough cable to fix the board neer the power connector.
Ok, it looks messy  :P

Step : Fix the fan
The fan is maintained with 3 screws from the outer chasssis (sorry I've no front picture...)
The PSU fan is the same size than the original fan. The screws heads must be flat because I fixed them from the external part of the chassis. They are also larger than the fan axes so I made struts on the fan axes. You can see one screw on the photo ; it looks not realy clean but it hold really right the fan ;)

The fan and the PSU are 2mm distant with this PSU!
Try to shake, rotate the X68000 to see if the fan and the PSU don't move at all and does not touch together.

Step : Fix the AC cable connector
I cut properly a small AC male / female cable to reuse cables and the wire cable anti-bend part. You can easily attach this part in the cable hole. There are a lot of possibilities here. It must be possible to not let a cable leave from the X68000 if you increase the cable entry size. But I like the male short cable which is more convenient than the original at least.

Now the X68000 has a ground pin.
I suppose you can keep the usage of the floating mass as there is still the shield, but it would be sad to not get benefit of it.

- got a standard Slim-PSU in your X68000 Compact (with a few hours of saw / cable cut)
- got a 220V PSU, a more convenient cable, linked to the ground  8)

Thanks to all the community for the incredible resources!
And long life to the good old electronic. ;)