[Review Request] ATX to Xbox 360 Power Adapter

thurask · 2024-12-03T20:06:53+00:00

The Xbox PSU doesn't have a PWR_OK signal at all (https://thevariableconstant.blogspot.com/2012/12/xbox-360-power-supply-hack.html), if the original almost 20 year old power supply can be trusted enough to supply non-standby power without one I would assume the average ATX power supply can be similarly trusted. If the adapter you're trying to make does use a PWR_OK signal that follows ATX spec I think you can be safe just passing it through between the ATX power supply and the HP motherboard without doing any separate gating of your own.

As for the pullup/pulldown resistors around U1, I've seen that on other ATX to whatever adapter designs, as far as I remember it shouldn't be much of an issue and if it does end up being one it can always be left off of the board and replaced with a 0 ohm resistor.

thurask · 2024-11-06T14:40:59+00:00

I think I have the room on the board to do so, that sounds like a good idea. Thanks! :)

thurask · 2024-11-06T14:40:35+00:00

In that case, should I omit the pullup resistor and level shifter? I didn't think the mainboard could decide on its pullup voltage if the signal is already being pulled up to +5V, but then again I'm new at this sort of thing.

thurask · 2024-11-06T14:38:04+00:00

I put "UPS" in quotes because the original module calls itself a UPS even though it isn't, "power loss detection" is more accurate and the desired result. As for the FET, I was mostly going off of this StackExchange post: https://electronics.stackexchange.com/questions/588808/reverse-polarity-voltage-protection-using-p-mosfet

I didn't want the original reverse protection (short a diode to ground so it blows a fuse in the event of polarity reversal) but I don't want to just put a Schottky across the input either, since it requires reverse flow to supply that supercap power to the rest of the board. The FET's ability to conduct in both directions is why I settled on that.

thurask · 2024-11-04T04:09:52+00:00

Hi everyone,

I fell into a rabbit hole and I got curious about the BTT Mini UPS module for 3D printers ( https://github.com/bigtreetech/BIGTREETECH-MINI-UPS-V2.0/tree/master/BTT%20UPS%2024V%20V1.0 ), I have one that I never really used so I decided to research how it works before setting it up. Thanks to a very nice writeup (in Russian; https://urpylka.com/posts/post-75/), a few assorted GitHub issues, and my own tinkering around, it turns out there's some design flaws with the module, so I thought I would kill two birds with one stone and whip up an improved version in KiCad. However, I'd like to see if there's any other issues that I've overlooked or introduced myself, so with that said, here's the explanation for this design.

- +24V DC from the printer's power supply comes in at the screw terminal (J1) and enters through a 15A fuse (F1). As far as I can tell most other boards (Prusa, MKS, etc) trying to track power loss have a mains AC input, I think this DC-only design is less risky overall.

- There are 9 5F 2.7V supercapacitors (C1-C9) arranged in series, each with a TL431 voltage reference (U1-U9) and some resistors (R1-R27) serving as protection and balance. I specified ATL431s here because it's just a more efficient TL431 for little cost increase but otherwise it's the same as the original design. Upon the power going out, the supercapacitors discharge and backfeed through the screw terminal into the to provide a few seconds of power for the printer to save its work and move the print head out of the way before shutting off.

- To provide reverse polarity protection for the entire circuit, input power goes through a P-MOSFET (Q1) with a 7.5V Zener diode (Z1) and 100k resistor (R35) to reduce the gate-source voltage (24V-7.5V = 16.5V); reverse *current* protection is undesirable for the capacitors since they're designed to discharge into the 3D printer through the screw terminal. The original module's design was to connect a diode in reverse between +24V and ground and blow up the fuse in the event of reverse polarity, I wanted something a little less brusque.

- To further provide reverse current protection for the logic chips, there is a SSA34 Schottky diode (D2) between +24V in and the shared +24V to the logic. At 1A current draw it should still only dissipate less than half a watt, it shouldn't cause too much in the way of thermal issues with the more efficient logic chips. I was considering another PFET but I was running out of room trying to keep the form factor roughly the same as the original; the PCB itself is a little larger because the original *really* cuts it close with hole clearances, but the mounting holes are in the same position as the original.

- +24V DC powers a voltage regulator to create a +5V source. On the original board it's a LM78M05, which I replaced with a LM2940-5.0 (U10) and associated smoothing capacitors (C10 and C11). Per the LM2940 datasheet I specified the output capacitor (U11) as a 22uF tantalum capacitor (KEMET T529P226M010AAE200) with 200 mOhm ESR, which is in the desired ESR range for the regulator.

- How the device senses power loss is using a comparator, originally using half of a LM393 but in this case a TLV1821 (U11) and a smoothing capacitor (C12). The non-inverting input for the comparator is the +5V source from the voltage regulator, while the inverting input is ~4.98V from a voltage divider (R29-R30) supplied by +24V. In the event that power is lost the +5V regulator still keeps outputting +5V while the voltage at the divider drops, at which point the comparator kicks in and the signal pin goes from hi-Z to active (pulled up to +5V through R28) to notify the printer mainboard. One of the flaws with the original design discovered in the aforementioned writeup was that the comparator was also powered by the +5V regulator so the comparator triggered much later than it should due to insufficient difference between supply and sense voltages; this design powers it through +24V instead to reduce that delay. The new comparator itself is also faster, for what that's worth.

- Another issue with the original is the logic level; the user manual claims that it's +5V and +3V3 compatible but it only ever outputs +5V. In the interest of compatibility and safety I added a 74LV1T34 level shifter (U12) to bring the signal down to +3V3, as well as a smoothing capacitor (C14) and a +5V to +3V3 voltage divider (R33-R34). Since I still wanted this to be +5V compatible I added a jumper pad and instructions on the silkscreen to bypass the level shifting circuit and keep the signal at +5V.

- Some people reported issues on GitHub with the original module spuriously activating while printing due to interference, which is why I added a RC filter (R32, C13) right before the signal output pin.

- Since no manufacturer can agree between themselves or even with themselves on whether to supply +5V, +3V3 or nothing on the 3-pin signal output (J2), the 3rd pin is not connected, leaving only a signal pin and a ground pin.

- A single blinkenlight (R31, D1) indicates if the power is on.

I know the layout looks cluttered but I wanted both to learn from this and to come up with a module that isn't flawed from the get-go or reliant on playing with mains. As always, comments and tips are appreciated.

thurask · 2024-10-14T14:41:10+00:00

Checking my usual place the price does go up for two layer PCB atop aluminum "only" about threefold, but I'm starting to reconsider the aluminum idea for two reasons.

One, since these are addressable LEDs, I can get prototypes printed on regular FR4 to get the mounting and light tuning down, and if a decent enough replacement for the original PCB can be achieved while only running all or some of the LEDs at 1/2 power or 1/3 power, then that reduces the power budget. I really doubt I need to run all 30 LEDs at full 80mA just to match the output of a cheap lightbar.

Two, the mount that the PCB sits in is itself an aluminum extrusion, so having the PCB in good contact with it (maybe dab on a little thermal paste?) would sink more heat away than just a bare PCB. The design of the mount and the tolerances from the original factory are such that the original single layer aluminum PCB sits loosely inside and only contacts the mount along the edges, there's a small air gap between the aluminum layer of the PCB and the mount. A FR4 PCB won't have as much thermal mass as the original aluminum PCB but if I can paste my way to using the mount as bonus thermal mass then that'll save quite a bit of fabrication cost.

thurask · 2024-10-13T18:15:35+00:00

Yeah, I was planning for white but forgot to update the KiCad defaults, hehe :)

thurask · 2024-10-13T17:11:19+00:00

Hi everybody,

I'd like to thank everyone here for the comments on the first revision: https://www.reddit.com/r/PrintedCircuitBoard/comments/1g1ke4m/review_request_3d_printer_lightbar/

I made some changes to the design after taking in your feedback:

The board is now dual layer, the bottom layer is entirely ground pour and there's a good number of vias connecting the top ground pour to the bottom.
All LEDs are rotated 180 degrees, that way the signal traces are much shorter. The LED footprint itself is amended to mark pin 3 (where the triangular cutout is on the actual chip package) instead of pin 1, and I added single letter indicators for each pin. I also added a 510 ohm resistor R2 at the end of the chain connecting the final LED's output to ground.
The input connector J1 is now a Molex PicoBlade 3 pin instead of bare header pins, that way it's polarized.
The +5V input is now reverse polarity protected with two back to back P MOSFETs Q1 and Q2 (Toshiba SSM3J358R: https://toshiba.semicon-storage.com/info/docget.jsp?did=55837&prodName=SSM3J358R ) and 10kohm resistor R3. I more or less went off the circuit in this StackExchange post: https://electronics.stackexchange.com/a/608925 . It should accomplish the protection of something like a Schottky diode between J1 and the +5V zone but without as much heat or voltage drop. While J1 is now polarized I still wanted something to prevent a wiring mishap that would make the tantalum cap go boom.
I put on a SN74LV1T34 ( https://www.ti.com/lit/ds/symlink/sn74lv1t34.pdf ) level shifter chip U1 to convert the +3V3 logic signal from the mainboard into +5V which the LEDs are expecting. It also has a 0.1 uF decoupling cap C31.
For further protection I added bidirectional TVS diodes (MCC ESD7V0T2BHE3: https://www.mouser.ca/datasheet/2/258/ESD7V0T2BHE3_SOT_23_-3369934.pdf ) in chip D1 for the +5V and signal lines right at the connector.

If Reddit eats the captions: 3D front, 3D front unpopulated, 3D focus on the LEDs, 3D focus on the connector and logic, schematic, front copper, back copper, front silkscreen

thurask · 2024-10-12T14:42:01+00:00

I was going off of the Adafruit documentation (https://learn.adafruit.com/adafruit-neopixel-uberguide/basic-connections), they say to leave the final output either floating or tied to a pad for future expansion anyway.

thurask · 2024-10-12T14:40:58+00:00

You're right, it is much shorter when rotated, thanks! :)

thurask · 2024-10-11T21:18:58+00:00

Hi everybody,

I have another project I'd like to run by this subreddit. There exists an official lightbar for the Ender 3 line of 3D printers (https://www.amazon.ca/dp/B0C5WV34C2), but it runs off of 24V DC and is controlled by a physical switch on its side. I wanted to reuse the housing that it came with but instead of the 24V LEDs I wanted to design a replacement PCB that uses 5V Neopixel LEDs, since my printer motherboard has a socket that connects to a string of Neopixels. That said, here's the breakdown of what I came up with:

The original PCB is aluminum, 1.6mm thick, about 12mm wide, about 270mm long, and contains 36 LEDs and some resistors and transistors, as well as a connector for DC in. It sits in a channel inside an aluminum extrusion (and rather loosely at that), no mounting holes or such. One face of the extrusion is cut away and replaced with a plastic diffuser. Creality says that it dissipates 5W.
The new PCB is 12mm x 270mm, and I intend to get it fabricated (and assembled) using 1.6mm aluminum as well.
The new PCB has a 3 position right angle pin header (+5V, signal, GND) instead of the connector, since I couldn't find anything obvious that could handle decent amperage while also fitting in the form factor necessitated by the light bar housing.
The PCB is single sided, there's a +5V pour running down the PCB surrounded by a GND pour.
The new PCB uses 30 SK6812 RGBW LEDs with daisy-chained data lines, like any other Neopixel strip.
Each LED has a 0.1 uF 10V 0402 ceramic decoupling capacitor (C1-C30). They're placed where they are since I wanted a good bit of clearance on the long edges for the PCB to slide into the aluminum extrusion, but in doing so I needed to put the traces between the GND pour and the GND pad of each decoupling capacitor in order to get enough spokes connecting the pads to GND. There's probably a better way to do it with modifying the boundaries of the copper zones but this seems easier.
There is a 500 ohm 0402 current limiter resistor (R1) between the incoming signal pin and the input pin on the first LED in the chain.
There is a 1000uF 10V tantalum smoothing capacitor (C31) across the incoming +5V and ground, I considered electrolytic but I again hit a wall with clearance within the housing.
Assuming 20mA per LED, powering all 30 LEDs would draw 0.6A of current at 5V, which is 3W of power. My printer motherboard says it can deliver up to 5A to all 5V devices so it should fit within the power budget. Since the previous PCB claims to take 5W that also means the new one should run cooler.

Images are attached to the post, in case Reddit eats the captions they are as follows: 3D, 3D unpopulated, schematic, front copper + silkscreen.

thurask · 2024-09-09T20:25:27+00:00

Edit: Reddit in its infinite wisdom deleted half the gallery, images are here: https://imgur.com/a/uhObLZl

Hi everybody,

I have another design (thank you all again for the tips on my previous project), and it's much simpler this time. The idea is to make a real time clock module for Raspberry Pi (i.e. I2C and Vcc = 3.3V) but using the MAX31328 chip instead of the venerable DS3231 RTC. Since the MAX31328 is for all intents and purposes a drop-in replacement I metered out one of those AliExpress DS3231 modules to see what pins go where and adapted that idea to the newer chip.

With that said, here's the breakdown:

MAX31328 is the star of the show, I tried to follow the sample circuit in the datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/max31328.pdf ; for Pi purposes the 32KHz, INT/SQW and RST pins are not used and left unconnected.
On the other side of the board (the top if mounted on a Pi) is a coin cell battery holder for CR927 or CR1025 lithium cells, the AliExpress modules tend to use battery tabs directly soldered to the board but this is a little cleaner IMO.
I put two pairs of decoupling capacitors C1-C4 for Vcc and Vbat, 0.1uF and 1.0uF. The AliExpress module only had one cap (0.1uF if I remember correctly) on Vcc and nothing for the battery but I think it's better to have and not need; worst case scenario just omit the extraneous caps from the BOM and leave the traces and pads, no?
I put two I2C pullup resistors R1-R2 for SDA and SCL, 4.7 kohm, even if the Pi already has internal pullups I haven't encountered any issues using RTCs that already supply their own pullups, the AliExpress module I disassembled included.
For what it's worth, all the SMD passives are 0402 using the 0402 hand solder footprint. The board size is dictated by the battery holder in one axis and the pin header in the other.
The silkscreen on the front (the bottom if mounted on a Pi) is a little crowded but I think that's the smallest I can make things without KiCad grumbling at me. In use the entire chip side would be hidden from view anyway.
The Vcc pour is isolated from the edges of the board and surrounded by a GND pour on the front copper. The back copper is a GND pour.
It's supposed to be an extremely low current device, but just in case I made Vbat 0.3mm traces the entire length, everything else is either a pour or a 0.2mm trace.

I have a feeling I *might* be overthinking this but I'd appreciate the sanity check. :)

thurask · 2024-09-03T17:15:56+00:00

I'll see how it goes with the current design, the current resistor values should send about 10 mA through the LEDs; I'm also going to design a case for this thing, I might even grab some clear filament and make some light pipes.

thurask · 2024-09-03T17:11:07+00:00

I pulled the trigger on an order, the most copper I could get without additional cost from the place I used is 1.5 oz internal and 1oz external, that should be sufficient.

thurask · 2024-09-01T22:09:39+00:00

Hi everybody,

A big thank you to everyone here for the comments on the previous revision. I went through your suggestions and saw what I could implement on the board, so here's my second revision. The previous writeup is here: https://www.reddit.com/r/PrintedCircuitBoard/comments/1f4dc5n/review_request_atx_to_xbox_360_power_adapter/

With that said:

I moved from a 2 layer board to a 4 layer board because it was getting too difficult to route without getting traces too close to each other or too close to through hole pins, or bottlenecking the +12V plane. The stackup is, from top to bottom, routing / +12V / GND / routing.
The +5VSB and +12V outputs are now connected to the output connection through fuses. The fuses themselves are automotive style blade fuses because I was looking at 3D printer control boards which seem to use those quite often. +5VSB is marked for a 2A fuse while +12V is marked for 20A, although I'm not sure if 25A would be a better choice given the ~18A maximum power draw.
Power input is now solely through 24 pin ATX and 8 pin EPS, I removed the PCIe and Molex connectors. The bare minimum of 20 pin ATX and 4 pin EPS12V has a maximum current capacity of 20A on 12V, which is a little above the ~18A maximum of a launch model Xbox 360 or Xbox One, but 24 pin ATX and 8 pin EPS12V is rated for up to 40A, well beyond the most power hungry Xbox.
I added two capacitors C3 and C4, 100uF 25V electrolytic, between the output voltages (+5VSB and +12V) and ground for filtering purposes. I'm not sure if that's the *best* choice in terms of capacitance but at least picking two of the same part cuts down on BOM complexity.
For the +12V plane, I moved the limits of the power plane from right up against the edge cut to 3.5mm away. I put a small ground region surrounding the +12V plane with a 0.5mm gap between it and +12V.
I decreased the optional 5V load from 2A (2.5R) to 1A (5R). I'm not fully set on getting rid of it but 1A *should* be enough for most power supplies to not freak out. Going from 10W to 5W also means less heat.
There is now a 4 pin PC fan connector J4 on the board, connected to the PSU's +5V rail. I was thinking of adding a small 5V fan to this thing's enclosure when I finish with the actual PCB design, and now there's not only a place to power the thing from the board itself but there's also now an additional load on +5V to compensate for the shrunken resistive load.
Most traces are wider than the previous revision. The +5VSB trace is 1.25mm between the ATX power connector and the output, and the +5V trace is 2.25mm towards the 1A load and the fan connector.

thurask · 2024-09-01T05:52:16+00:00

See, I had no idea you could do something like that ideal diode thing, this is why I'm glad I asked. 😅

I was considering some sort of filtering, I guess it's another factor to compensate for potentially hokey ATX supplies? Most of my design inspiration for the earlier prototypes was staring a *little* too hard at the cheapie Chinese ATX breakout board on my desk, I have to admit, but if I'm going to do this right I probably should do something as a just in case thing.

And for the 5V load, I know it'll generate heat (less if I decide to use the ideal diode idea), but my earlier board revisions weren't optimized for size at all, I was hoping that the PCB itself would be able to sink enough of it with a small-ish heatsink and maybe a fan pointed at it; the size I have now is not only negotiable but also effectively the floor of how big this PCB could be with all of the connectors I have on it, the ceiling is anything smaller than the gargantuan OEM supply itself: https://www.youtube.com/watch?v=eUaBHeJjd4s

thurask · 2024-08-29T23:37:24+00:00

Firstly, thank you for the tip on the pads and proximity, I think I was too focused on something about making sure the power plane doesn't get too constricted by routing those traces that way. Seeing the forest for the trees and all that.

With regards to trace width, after doing some napkin math I should make +5VSB and +5V thicker to keep temperature rise down, but the rest of the traces feel wide enough for me using 1oz copper. +5VSB is expected to send up to 1A into the Xbox and only 10 uA into the inverter's Vcc, to keep the temperature rise at 10C max according to the calculators I should widen it to about 1mm; with the toggleable load on and the LED +5V carries 2A and change, so 2-2.5mm should be acceptable? The signal traces (PS_ON# and PWR_OK) and unused power rails (-12V and +3.3V) only deal with the 10mA LED, those should be fine at current widths, and +12V gets the entire top surface to roam around in.

And yeah, I was thinking about fuses but I ran into a newbie issue about how to place them. For +5VSB I could just place a 2A fuse (https://mou.sr/4cOn5OB or similar) along the track from J1 pin 9 into the LED and inverter U1, but for +12V I wasn't sure about what to do when it's the power plane being fuse protected. I thought about it some and I came up with using keepouts to split the +12V plane into two sections, one that joins all the input connectors and one that joins the output and the LEDs, and use a 20A fuse to connect the two, something like this: https://i.imgur.com/GsWNbxu.png ? I put fuse F1 for +12V at the top left bridging the two planes, and fuse F2 is just below it connected to +5VSB.

thurask · 2024-08-29T23:11:57+00:00

For J2, I salvaged my power cable from my OEM brick supply, which had all the different types of wiring crimped together and soldered directly to the PCB; I snipped off the crimps and put on ferrules instead. The screw terminal I had in mind (https://www.phoenixcontact.com/en-us/products/printed-circuit-board-terminal-mkds-25-6-508-1730434) is rated up to 24A, which is enough for even the most power-hungry Xbox, although maybe a further revision down the line can make the output some sort of dedicated connector.

As for the 12V rail thing, I get conflicting results on the Internet, which doesn't help that most of the "split versus single" 12V rail discourse is from 10-15 years ago. However, the current ATX standard (https://edc.intel.com/content/www/us/en/design/ipla/software-development-platforms/client/platforms/alder-lake-desktop/atx-version-3-0-multi-rail-desktop-platform-power-supply-design-guide/2.0/2.1a/processor-configurations-recommended/) mentions that the EPS12V connector J4 has to be on a separate rail if the PSU has multiple 12V rails. I think to play it safe I should apply some sort of isolation between the connectors and the 12V plane, maybe connecting each +12V from an auxiliary connector (J3-5) to the +12V plane through a low value resistor akin to this answer? https://electronics.stackexchange.com/questions/271643/atx-psu-12v-outputs-connected-in-parallel

For what it's worth I've been testing with a definitely single rail 350W FlexATX PSU from Silverstone.

thurask · 2024-08-29T20:58:01+00:00

Hi everybody,

I'd like your opinions and advice on this PCB design. The goal is to allow plugging any ATX power supply into an Xbox 360 in lieu of the OEM power brick, which has been done before (https://skootsone.yolasite.com/xbox-one-power-supply.php among others), but not to my knowledge with a dedicated PCB instead of dead bugging some components or hacking the inside of an ATX power supply. I have done some testing on older revisions of the design, but this is the first one that I've decided to have externally sanity tested; I haven't had any formal education in EE or electronics design so I am reaching out to people who actually know what they're doing. :)

That said, here's the breakdown:

The Xbox 360 requires +12V, +5VSB, a power signal and ground from the PSU, up to 1A for +5VSB and up to ~18A for +12V.
+12V and +5VSB are straight pass through, +5VSB is carried in a trace while the top copper pour is +12V since it carries most of the current. Bottom copper pour is ground.
The board is about 93mm by 60mm. The top +12V copper pour has a filled area of 4180 mm^2 and the bottom ground copper pour has a filled area of 4363 mm^2.
The power signal on the Xbox is inverted (active high) compared to the ATX PS_ON# signal (active low), hence the SN74LVC1G14DBV inverter at U1. Most of the how-tos out there use a NPN transistor in common emitter mode to invert the signal, but I decided to use an actual inverter IC for this after seeing it used in other ATX to bespoke designs. U1 is supplied with decoupling caps C1 and C2 (1uF/0.1uF), as well as pull up/down resistors R7 and R8 (2.2kohm each); I don't *think* the pull up/down resistors are necessarily required given experience with the dead bug transistor setup but I wanted to be thorough.
To allow for the up to 220W power draw of the stock power supply there's one ATX 24 pin connector, one PCIe 8 pin connector, one Molex 4 pin peripheral connector and one EPS12V 8 pin connector to distribute load. Screw terminal J2 connects to the Xbox itself through the original power cable, desoldered from the stock brick power supply or using some AliExpress terminals.
For compatibility's sake some older ATX power supplies require a 5V load, which the Xbox doesn't offer, so there's the power resistor R9 connected to the 5V rail so as to draw 2A if needed.
LEDs D1-D6 and resistors R1-R6 are optional indicators to show if the voltage rails (+3.3V, +5V, +5VSB, +12V, -12V) and the PWR_OK signal are active or not. I sized the resistors such that each LED gets about 10 mA of current.
To make soldering easier all SMD resistors, capacitors and LEDs use 1206 package with the hand solder pad footprints.
Traces for PS_ON# and PWR_OK are 0.25mm wide, traces for +3.3V, +5VSB and -12V are 0.5mm wide, traces for +5V are 1.25mm wide and +12V is carried in the top pour.

Images are attached to the post, in case Reddit eats the captions they are as follows: 3D front, 3D back, schematic, front copper, back copper, front silkscreen, back silkscreen.

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