Easy PicoPSU

[X-Col]

Here is how the rear of the ACE looks, pretty near stock. And the on/off switch on the PSU works 

[mattsoft]

@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!

Nice! So the shutdown issue was perhaps PicoPSU-brand related?

[X-Col]

Nice! So the shutdown issue was perhaps PicoPSU-brand related?

I would assume so,  I now have 3 PicoPSU's and only 1 of them works with the X68000. All 3 of them work fine in a PC.
It seems it's a bit of a lottery if a Pico will work with the system shutdown/startup circuit of the X68000 

[leonk]

Any progress on the Easy PicoPSU complete solution? I just got an XVI HD in, and the "lego" piece power supply is shot.  Everything is black in there, fuse popped.. what a disaster.  Looking for new PSU solution.

[mattsoft]

Any progress on the Easy PicoPSU complete solution? I just got an XVI HD in, and the "lego" piece power supply is shot.  Everything is black in there, fuse popped.. what a disaster.  Looking for new PSU solution.

i have all the parts, but have been sidelined by my ACE deciding it doesn't want to work anymore so I've been focusing on trying to get it working. I'll get back to it over the holiday break.

[leonk]

I just want to say that this device worked great for me in restoring an XVI. I did notice that 3 5V pins on the pico ATX connector aren’t connected but that should be fine and there are enough 5V sources.

I did find a strange issue with one of my connected FD. It doesn’t work. The 5V line is only abou 3.5V. The other 5V lines around the system are at 4.95V. I wonder if there’s something wrong with this FD that pulls the 5V rail down hard. I replaced all the caps. Hmmmm

[mattsoft]

I just want to say that this device worked great for me in restoring an XVI. I did notice that 3 5V pins on the pico ATX connector aren’t connected but that should be fine and there are enough 5V sources.

I did find a strange issue with one of my connected FD. It doesn’t work. The 5V line is only abou 3.5V. The other 5V lines around the system are at 4.95V. I wonder if there’s something wrong with this FD that pulls the 5V rail down hard. I replaced all the caps. Hmmmm

There are 4 +5VDC rails on the PicoPSU. I am using 3 of the 4 for this project; they're on the bottom of the board. Make sure you are using a REAL PicoPSU and not an aftermarket unit -- the voltages on those knockoffs can be whacky!

[mattsoft]

New PCB with onboard AC-DC to be tested this weekend. This aims to be an all-in-one internal replacement for the lego brick PSU. Preview of board attached. If this works OK, I'll post the gerbers and BOM to GitHub.

[leonk]

I'm using the real PicoPSU from short-circuit.com, the 120 Watt version.

[leonk]

New PCB with onboard AC-DC to be tested this weekend. This aims to be an all-in-one internal replacement for the lego brick PSU. Preview of board attached. If this works OK, I'll post the gerbers and BOM to GitHub.

Can you post pics of underside as well?  I want to confirm the traces.

Also, for your latest design, one should know they need to choose one or the other, not both!  (i.e. use PicoPSU or AC/DC converter) 

[mattsoft]

New PCB with onboard AC-DC to be tested this weekend. This aims to be an all-in-one internal replacement for the lego brick PSU. Preview of board attached. If this works OK, I'll post the gerbers and BOM to GitHub.

Can you post pics of underside as well?  I want to confirm the traces.

Also, for your latest design, one should know they need to choose one or the other, not both!  (i.e. use PicoPSU or AC/DC converter) 

Bottom attached.

The all-in-one will require an AC-DC converter + PicoPSU to condition the power and provide the various voltages (+ SB). It's inspired by the work user Arcade did in this thread: https://nfggames.com/forum2/index.php?topic=5542.0

[leonk]

Oh.. right.  my mistake.  Rather than using an external 12V power source, you are using it as all internal.  In this case, what's not seen, is the 12V + GND wires for the PicoPSU will not come from the barrel style connector, but rather jump in from the AC/DC internal PSU.  The internal PSU will then get it's AC in from the stock connector / after the power switch.  Very nice. 

I think it would still be safe to keep the internal fan off as the AC/DC converter will be switching type which has very high efficiency with minimal heat generation (unlike the more traditional linear supplies that dissipate a lot of heat)

[mattsoft]

Oh.. right.  my mistake.  Rather than using an external 12V power source, you are using it as all internal.  In this case, what's not seen, is the 12V + GND wires for the PicoPSU will not come from the barrel style connector, but rather jump in from the AC/DC internal PSU.  The internal PSU will then get it's AC in from the stock connector / after the power switch.  Very nice. 

I think it would still be safe to keep the internal fan off as the AC/DC converter will be switching type which has very high efficiency with minimal heat generation (unlike the more traditional linear supplies that dissipate a lot of heat)

Yeah, the AC will run direct to the AC-DC converter and the 12VDC will come from the AC-DC converter into the PicoPSU (via wires). Should be pretty slick.

When it's done, I'll send you a couple of boards to play with. I'm open to ideas to improve it -- for example, putting in a more powerful AC-DC/PicoPSU.

[leonk]

I was thinking about this solution, and realized what has been bugging me.. the missing ground!

In Japan (or at least when these computers were made) all outlets were 2 prong 100V / 60hz AC.  Hence all electric devices were only 2 prong.  Reference ground for computers is very important, hence why the ground posts were added (and used!).  A lot of these old power supplies also use a simple transformer to step down the voltage.. so which pin gets 100V AC vs Neutral isn't that important.

On the other hand, the modern AC/DC 12V switching power supply you want to use requires a proper ground (to reference against in order for the over voltage and other protections to work correctly).  I'm also not too sure about what will happen if you feed 110V AC into ground pin.. I suspect not a good thing.

This is why, when I put a modern power supply into my OG X68000, I replaced the power cord on my X68000 with a 3 prong one.  This way, I know for sure what is AC, Neutral and ground.

As for your original solution, it worked great because the external 12V 10A power supply is properly grounded and has all the required fuses/safeties in place.

[mattsoft]

I was thinking about this solution, and realized what has been bugging me.. the missing ground!

In Japan (or at least when these computers were made) all outlets were 2 prong 100V / 60hz AC.  Hence all electric devices were only 2 prong.  Reference ground for computers is very important, hence why the ground posts were added (and used!).  A lot of these old power supplies also use a simple transformer to step down the voltage.. so which pin gets 100V AC vs Neutral isn't that important.

On the other hand, the modern AC/DC 12V switching power supply you want to use requires a proper ground (to reference against in order for the over voltage and other protections to work correctly).  I'm also not too sure about what will happen if you feed 110V AC into ground pin.. I suspect not a good thing.

This is why, when I put a modern power supply into my OG X68000, I replaced the power cord on my X68000 with a 3 prong one.  This way, I know for sure what is AC, Neutral and ground.

As for your original solution, it worked great because the external 12V 10A power supply is properly grounded and has all the required fuses/safeties in place.

Yeah, that is a good idea. This new solution does tie the ground of the AC-DC into the PicoPSU on the board but that is obviously worthless if the whole thing isn't tied into a real Earth ground. The missing piece is if you use the original power cord to the AC-DC mains terminal -- it is missing ground like you say. When I build this new one, I will use a 3-wire power cord with proper neutral, hot, and ground, and wire that into the AC-DC mains terminal.

[leonk]

If you use a pico PSU (or ATX psu for that matter) don’t power everything off the ATX connector. You’ll run into weird power issues (like power button not working). The connector can not supply enough current for the entire computer. I suggest plugging the floppy drives into the 4 pin moldex that’s plugged into the picoPSU. You’ll avoid a low voltage situation that the X68k will detect and cause issues.

[mattsoft]

Some very minor progress. Hah! Boards finally arrived, AC-DC converter fitted, board fits in metal PSU case perfect. Hopefully solder and test tomorrow night.

[mattsoft]

First board is built and voltage and soft power tests are good. Hot/neutral polarity on the AC matters with this AC-DC converter it seems. If I reverse hot/neutral into the AC-DC converter, it seems that the soft power does not function and it forces the PicoPSU on. So I need to first do a little more testing and verify this and then just to be safe, I'm going to source a proper 3-pronged AC power cable that fits nicely and allows me (a) ground the damn thing and (b) guarantee hot is hot and neutral is neutral from mains to AC-DC to before doing any more tests. It does all fit inside the original metal case though, even with the fan hooked up. It's definitely very clean.

[leonk]

I want to reiterate an import finding I've made with both the OG X6800 running a PC ATX PSU as well as PicoPSU on the XVI HD.

Do not power the floppy drives from the ATX connector.  Even when PicoPSU is used inside a standard PC, it's not designed for that.  That's why breakout cables are provided on the PicoPSU to power drives (floppy, CD-ROM, Hard Drives, etc.)  The ATX connector can not reliably provide enough current for both the computer as well as FDD's.

[mattsoft]

I want to reiterate an import finding I've made with both the OG X6800 running a PC ATX PSU as well as PicoPSU on the XVI HD.

Do not power the floppy drives from the ATX connector.  Even when PicoPSU is used inside a standard PC, it's not designed for that.  That's why breakout cables are provided on the PicoPSU to power drives (floppy, CD-ROM, Hard Drives, etc.)  The ATX connector can not reliably provide enough current for both the computer as well as FDD's.

when i get this thing done and posted to GitHub, i'll include that in the readme. it's really easy to just connect the FDD leads to the 4-pin MOLEX on the PicoPSU.

in a future redesign, it might be interesting to run the 4-pin MOLEX from the PicoPSU to the board and break-out the +5VDC & +12VDC from the MOLEX to FDD headers on the board.

[leonk]

That will be handy if you don't want to do any soldering at all.  I ended up soldering a female 4 pin molex connector on my FDD power cable (you know, the yellow/black/black/red 5.25" connector).  This female connector then plugs into the male plug that comes out of the picoPSU.

If you do go down that route, make sure ground also comes from this connector.  I think the problem might stem with the wire gauge .. only so much current can go down a given wire.  Maybe that's why there are 2 ground wires.

[mattsoft]

Another small update...

I have the PicoPSU v2 wired up and tested good. Per @leonk's suggestion, I wired in a 3-prong grounded cable which grounds the entire assembly and electrical system of the X68000. Had to 3D print a cable relief to the metal PSU box. With it all screwed together it looks close to stock!

Unfortunately, I cannot find the 4-pin JST cable for my PicoPSU to hook up to the FDD lead (again, per @leonk's suggestion). UGH! Will need to order new one.

v3 of this design will definitely simplify the wiring by running the PicoPSU 4-pin JST to a header on the PCB that explicitly powers the FDD.

Now if I can get some time, I'll get this posted to my GitHub for others to play with. I have spare boards if anyone wants one.

[leonk]

Thank you for all your effort. If I was to rebuild an x68k today I wouldn’t think twice about using your wonderful design.

[TD-Linux]

I did a very similar PSU mod, with the exception that I didn't make a PCB - a 3D printed plate holds the PicoPSU and open frame supply in place.

One problem I've been having is that after about an hour, the machine starts resetting. I basically see a fast square wave on the picopsu's 12V line. Oddly, the problem goes away if I disconnect the -12V line. Have you had any similar problems?

[leonk]

Sounds to me like a defective PicoPSU / not real one / clone.

I had no issues with my PicoPSU.

[TD-Linux]

Turns out it's not the PSU's fault, I can reproduce the same problem by applying -12V with a bench supply. Sorry for the noise, I'll move to a separate thread if I figure it out.

EDIT: it was actually me forgetting to add a pullup to the x86000's PSU CTRL line. Despite being reverse polarity to ATX, it's still open collector. Without a pullup, it will slowly float high, but you'll get tons of weird behavior, such as the neighboring -12V line coupling in. Remember the resistor!

[amigo-mexicano]

What a cool project! Been reading all day long about it. Congrats mattsoft, and thanks for sharing!

Now, this says it's for the ACE, but should work for any model, right? I want to use it on a SUPER...

[mattsoft]

What a cool project! Been reading all day long about it. Congrats mattsoft, and thanks for sharing!

Now, this says it's for the ACE, but should work for any model, right? I want to use it on a SUPER...

I don't know what a Super's PSU looks like. The board was measured and designed to fit into an ACE/ACE HD "lego" style PSU. If the Super has the same shape PSU and basic power requirements, then it should work. But your mileage may vary.

[leonk]

As Matt mentioned, it will work in any lego PSU. I installed it into an XVI HD.

[amigo-mexicano]

Great, I'm gonna try on a PRO also, and see how it goes...

[thegirlg33k]

It works wonderfully! Now to actually get it hooked up to my OSSC and test.

[X-Col]

Amazing work!

Well done mattsoft!! 

[hyrulebr]

Hey Mattsoft!

Just won a X68000 OG (CZ-600C) and for sure it will need a new ps. Do you have anything for a OG? I don´t know if the ps and connectors are different from a Ace for example.

[leonk]

I restored an OG X68000 as my first one ..

The power supply here is not the same.  The OG X68000 doesn't have a "tetris" PSU, it has a PSU that's more similar to a 1U micro PC.

Don't use the original PSU.  Replace it!  Also, the other killer of these computers is the on board save battery.  They put it a few mm away from the main crystal!!  If the battery leaked, it would have killed it.  Contact me and I can help you restore that.

[hyrulebr]

Hi Leon!

I appreciate your message and I do want your help! 

It will take a while to me receive the OG. I used shoppingmalljapan to buy from YAJ and I intend to use all 30 days of free storage I have. This will help me to have the money to pay shipping to Brazil, which is very expensive for a (heavy) X68000 ...

I bought this one:

https://page.auctions.yahoo.co.jp/jp/auction/n335264270

I expected to pay less in an OG but lack of patience overcame me! I was tired of waiting for a better price.

The good news is that it´s turning on, asking for the OS and ejecting discs. That's a good sign but I know that I can´t keep this ps.

I already have a 1MB extension board bought brand new from Beep!. Just want that both drivers are in working conditions. 

[mattsoft]

Hey Mattsoft!

Just won a X68000 OG (CZ-600C) and for sure it will need a new ps. Do you have anything for a OG? I don´t know if the ps and connectors are different from a Ace for example.

the original PicoPSU board (https://github.com/mattsoft/X68K_EZ_Pico_PSU) should work fine for an OG X68000 as it doesn't rely on the "lego" style brick. i don't have any made up at the moment, but you can have several made from China for around $20. or you can just wire the circuit manually without the board.

the newer style board I do have spares for are only for the "lego" PSU and therefore will not fit the OG.

[aje_fr]

I'm always amazed that people spend so much time trying to replace these blocks while once repaired they are really reliable.
I'm sure you spent as much time replacing the blocks rather than repairing it.

[vanpeebles]

Even repaired, the original PSU can be a weak link. I live in a 240v country, so it's a way better solution than using a dodgy original with a stepdown tagged on the end as well. 

[leonk]

Even if it’s repair to like new condition, the original design is more than 30 years old and poor. It will fail again the same way. PSU technology improved. Why take the chance?

[aje_fr]

Even if it’s repair to like new condition, the original design is more than 30 years old and poor. It will fail again the same way. PSU technology improved. Why take the chance?

The design is maybe 30 years old but still really, really reliable, no specific components, only discrete. No compromise on cost vs quality when designed. If I follow you, why still using original motherboard when a fpga could do the same...

Why when you change all leaky components it still works perfectly. The psu is really well designed.

I don't think modern psu could last so much time... From my experience, their lifetime is around 10 years.
Modern psu are too sensitive and not reliable due to the fact that their components are used to their limits to save costs.

And when you repair the original one, you could put high quality components. Something you'll never find in cheap modern psu.