Easy PicoPSU

[mattsoft]

Hi all - my recently acquired X68000 ACE had a dead PSU that I tried to resurrect with new caps and zeners with no luck. So I bought an AC-DC adapter and PicoPSU and wired it up with success -- but I hate the messy bundle of cables and would like a more finished look that uses the ACE's PSU cage.

I saw this blog: https://m.blog.naver.com/PostView.nhn?blogId=iolokim&logNo=221075411751&proxyReferer=https%3A%2F%2Fwww.google.com%2F -- but cannot find that adapter board available in the U.S. So...I'm using it as a reference and building my own. Attached is a very early preview of the board with just the soft power + inverter plotted. I hope to have samples of the board in November and if it works, I will make the schematics available for free.

If someone else has already done this, please holler!

[leonk]

i look forward to this pcb. if you offer the gurbers for free it will go a long way to preserving the x68k for years to come; long after any of us leave this hobby. All your hard work will not be lost.

just a thought.

[mattsoft]

If it works, the gerbers will be free. I'll probably even have some spare from manufacturing mine to sell at cost.

Progress made. Switched CAD software to KiCad and have completed the first drawing. I want to double-check all the traces including weight and width, and plot the mount holes in the corners. I'm planning on 6-8 amps for the +5, -12, and +12 routes which is probably overkill. I may also add a jumper to bypass the soft power on in case you need to troubleshoot that functionality of your X68000 (like I have had to do). I'm a noob at this, so...

3d renders attached. * whoops, the +12V on the right side is mislabeled -- it's actually a 3rd +5V.

[mattsoft]

Prototype ordered...should have first build soldered up for testing in a couple of weeks.

[gypsie]

Very good mattsoft!

[Jehuty]

Nice Work. Like to get one PCb or Files to get one. Thanks.

[mattsoft]

the prototype boards have shipped! there are 10. assuming they work and I don't destroy any in my testing, i should have around 8 left available. the cost will be USD$5 per unpopulated board + shipping which is basically my cost. i'll also post the gerbers and BOM on GitHub if you want to improve the design or make your own. this is all assuming they work!

[leonk]

If it works.. I'll take 1.

[ShootTheCore]

I'm interested in one too.

[gypsie]

me too

[rkrenicki]

I ran into the same issue with my ProII power supply.  I replaced all of the caps, zeners, 5 transistors, several resistors, and the optoisolators and even the T2 transformer.. with no luck at all.  I think one of the replacement transistors is bad, but I just got too frustrated with it and decided to go the ATX route.    I literally just got the machine to boot with an adapter cable that I made up, but I would like a more polished product for sure.

Count me in for one, Thanks!

EDIT:  Can you tell me the overall dimensions of the adapter?  I am wondering if it along with the PicoPSU itself would fit within the stock power supply case.. 

[mattsoft]

I ran into the same issue with my ProII power supply.  I replaced all of the caps, zeners, 5 transistors, several resistors, and the optoisolators and even the T2 transformer.. with no luck at all.  I think one of the replacement transistors is bad, but I just got too frustrated with it and decided to go the ATX route.    I literally just got the machine to boot with an adapter cable that I made up, but I would like a more polished product for sure.

Count me in for one, Thanks!

EDIT:  Can you tell me the overall dimensions of the adapter?  I am wondering if it along with the PicoPSU itself would fit within the stock power supply case..

its 61mmx94mm and designed to fit in the original case with the PicoPSU in front of the fan. the mounting holes are positioned correctly to screw right in. i haven't quite figured out the rest yet, but i plan to put the pico's DC in jack in place of the AC input. i will have the test boards completed this week and will post pictures and results.

[hoshikawa]

I've had success removing the FG ground terminal and installing the DC in jack there, it looks really clean from the back. I tried putting it in the AC in hole but it just doesn't look right imo.

[mattsoft]

Soldered up and the board works. Mostly. Like a dumbass, I failed to wire up pin 7 of the inverter to ground. Doh! I ran a test wire from pin 7 to ground and the adapter works perfectly! Success! My ACE boots from soft power and floppy.

So...I am going to fix this in the design and make a couple other small changes and then get final boards made and publish the gerbers and BOM.

In the meantime, I have 10 of these boards available. Because of the design flaw, I’m offering them free + the price of shipping. I can include a digikey BOM too. U will need to run a wire to ground the inverter. Even with this flaw, it makes a tidy Pico conversion and gets rid of any cable rats nest. PM me if u want a board and how many u want. Fixed boards will be another 3-4 weeks out.

[ShootTheCore]

I don't mind running a ground wire.  PM sent.

[kamiboy]

With all that free space left inside the PSU case I am sure you could even find room for the whole power adapter inside there. I am sure that if you remove the plastic shell of that thing it will take up even less room.

Luckily all my original PSU's work, but if I had to do something like this I would prefer to have one cable coming out of my machine that plugs directly into the wall.

[mattsoft]

With all that free space left inside the PSU case I am sure you could even find room for the whole power adapter inside there. I am sure that if you remove the plastic shell of that thing it will take up even less room.

Luckily all my original PSU's work, but if I had to do something like this I would prefer to have one cable coming out of my machine that plugs directly into the wall.

That is my next goal.

[mattsoft]

Project is on GitHub: https://github.com/mattsoft/X68K_EZ_Pico_PSU

If you'd like to clone and modify for your own use, go for it! I'd love changes by way of pull requests too. If you have questions, let me know. Have fun!

[vanpeebles]

Please put me down for a fixed one

[hyrulebr]

Congrats Matt! Nice project! 

I´m also interest in one mounted board if you plan to sell some.

[mattsoft]

I've decided to change v2 of this board and bring the AC-DC converter INSIDE.

[mattsoft]

V2 board with integrated AC-DC adapter has been ordered! More soon...

[leonk]

what is the advantage of doing v2? easier to find external AC?

[mattsoft]

The only advantage is that it will be 100% internal so it will look stock -- no need for external PSU.

[leonk]

with rev2 it will run on mains? 120/220V AC?

[mattsoft]

with rev2 it will run on mains? 120/220V AC?

Yep. As soon as I have the boards I will post a build.

[neko68k]

nice work, man <3

[kamiboy]

Now this is looking like an ideal solution. All internal, direct from machine to wall socket is how it should be.

[leonk]

I have a microATX PSU in my OG X68K; so I have an all internal solution.  But even though it's a MicroATX PSU, there are a lot of components there to make sure power is clean, safe, with over voltage, over heating, etc. protection all there.  Designing a Power Supply is not a simple task.

So the choice of components that make up this PicoPSU adapter can either make it or break.

Looking forward to see the solution.

[mattsoft]

I have a microATX PSU in my OG X68K; so I have an all internal solution.  But even though it's a MicroATX PSU, there are a lot of components there to make sure power is clean, safe, with over voltage, over heating, etc. protection all there.  Designing a Power Supply is not a simple task.

So the choice of components that make up this PicoPSU adapter can either make it or break.

Looking forward to see the solution.

Yeah, and I'm self admittedly an amateur so...

I'm using this AC-DC converter: https://www.digikey.com/product-detail/en/bel-power-solutions/ABC75-1T12L/179-2836-ND/5629042 to provide 12VDC. It has over-heat shutdown protection and runs pretty efficiently. I'll be curious to see how warm it gets with the fan blowing air directly over it. I used various published sources to determine realistic power usage of an ACE running < 4MB, dual floppy, and HDD, and it came in WELL under 75W for continuous operation, and was under 75W at power-on time. If you have a bunch of add-ons, 75W might be tight. There is a 95W option as well but would cost more all around.

It will also use a PicoPSU to take the 12VDC from the AC-DC converter and provides 12VDC and 5VDC (along with power-on and stand-by 5VDC) to the X68000. The PicoPSU provides over voltage protection to the components downstream.

So I think it will work great pretty well as long as it stays cool.

[X-Col]

Hi Matt,

I got round to populating one of the version 1 boards you sent me and trying it on my ACE.

I have 2 PICO PSU's and here are the results:
The 'bootleg' PICO does not turn on when the power switch is pressed (continuous red light)
The genuine PICO 120 will not turn off - with button in the off position the system seems to go into a shutdown loop (no red light)

However, it works perfectly with a genuine ATX PSU! 

Any ideas? 

[mattsoft]

Hi Matt,

I got round to populating one of the version 1 boards you sent me and trying it on my ACE.

I have 2 PICO PSU's and here are the results:
The 'bootleg' PICO does not turn on when the power switch is pressed (continuous red light)
The genuine PICO 120 will not turn off - with button in the off position the system seems to go into a shutdown loop (no red light)

However, it works perfectly with a genuine ATX PSU! 

Any ideas? 

Weird. And just to confirm, your ATX PSU is plugged into the PCB in place of the PicoPSU? If so, then the inverter chip circuit is correct, but something about your PicoPSU is different. I'll do some more research and see if there are differences between PicoPSUs.

[X-Col]

Weird. And just to confirm, your ATX PSU is plugged into the PCB in place of the PicoPSU? If so, then the inverter chip circuit is correct, but something about your PicoPSU is different. I'll do some more research and see if there are differences between PicoPSUs.

Yeh, I just plugged in the ATX PSU into the connector where the PicoPSU was and it worked fine. Strange that both my Pico's exhibit different behaviours 

The one that won't turn off is this one: (PicoPSU-120 (RS) 120w output) https://www.ebay.co.uk/itm/PicoPSU-120-RS-120w-output-12v-input-DC-DC-Power-Supply/263572842034?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
The other one is the original Pico I was using before I installed this board. It used to work fine, but now won't turn on. 

Strange indeed!

[mattsoft]

Found this during my lunch hour today: https://www.colonel-panic.org/PicoPSU/

The 4.7k ohm resistor on the PCB should be doing this but maybe 4.7k isn't enough resistance? maybe try a 10k ohm?

[elmer]

mattsoft: You can definitely put me down for one of these, if you have any extras to sell ... it would be lovely to finally get my X68000 to turn on after all of the years that I've owned it.

[mattsoft]

Just a status update -- this has been temporarily sidelined by the fact that my ACE is no longer working and I'm spending time trying to get it working again.

[X-Col]

Sorry to hear that Matt, hope you figure it out! 

These machines are a lesson in S&M; still have issues with sound 'cracking' on my Compact and my ACE refuses to play nicely with PicoPSU's.... 

[leonk]

From all the electronics repair I’ve done over the years, nothing has kicked me harder than an X68k. When you’re down, it just keeps on kicking.

[mattsoft]

From all the electronics repair I’ve done over the years, nothing has kicked me harder than an X68k. When you’re down, it just keeps on kicking.

Yup. I've got the bruises and broken ribs to prove this.

Got 2 more X68000 ACE's coming in from YAP for spare parts. Hoping to have enough to get this baby up and running again.

Or maybe I'm just pouring money down the drain.

[X-Col]

@mattsoft

Just to let you know that another PicoPSU arrived today and it works nicely with the X68000!!

Fitted your version 1 board today and all is good 

Thank you, and hope you find the problem with yours!