In this thread we build the projects that others have shared

[hatmoose]

I also wanted to to some mechanical safety testing on the Female molex socket
The socket itself is pretty much indestructable, Molex make top quality stuff and their materials are awesome, no concersn there

I was mainly concerned that the retention in the 3D printed shell might break or come away. Or that the molex socket might fall inwards into the shell.

I was unable to break this with my bare hands, or with a hammer. Eventually I managed to snap it off with vice-grips from inside the shell.


So pretty happy from a mechanical safety perspective. Once in it is not possible to remove without pliers from the inside and destroying the entire shell.

 

[hatmoose]

Since I needed a new shell anyway I re-made the internal wiring harness in what I should have made it in the first place
15AWG silicone was much more practical and workable than the 14AWS PVC wire I had been using before. I couldnt be bothered waiting 10 days for shipping, so I cut up some new-old-stock power cables that I had left over from when I worked at Sun microsystems


This wire is much thicker than I normally work with, and the automatic wire stripers dont cut the insulation particuarly cleanly. This would have caused messy crimps when crimping onto the molex pins - there is only about 1/2mm of tolerence in the dimensions. So I had to strip these with manual wire cutters.

Cut on left = automatic, unsuitable for crimping Molex Mini-fit JR pins
Cut on right = manual, much slower but much neater


Shell complete and wired and ready to be screwed onto the terminal block of the power supply. Fork terminals are traditionally rated by color - the Blue ones are rated for 14-16AWG and 22-32amps - which is much more than plenty for this application (the socket is fused for 10amps)
... unless you buy them off aliexpress in which case the color has no relation to the electircal rating, or safety, or anything. Please do not buy mains power stuff off Aliexpress...


The +5v trimpot on the meanwell power supply was woefully unsuitable for this particular application, it's not even a proper trimpot, its a Preset Resistor and it's only rated for something like 20 twists. and it's in a stupid place which invites people to poke a metal screwdriver into an open-frame mains powered device. SO that had to go too.

I took it out and replaced it with a proper linear potentiometer that is rated for about a bazzilion twists, and moved it to the front of the case where it belongs for an application like this.

And here it is, all done! - again I'm expecting a flood of job offers to be come a professional product photographer any minute now


Next on my list is replacing that sweet little 14" consumer SCART TV with a proper PVM - I'll be using a Sony PVM 9L2 because that's what I've got. The 9L2 needs an expensive and rare 129x card in order to be able to display RGBS. And the minigun supergun only produces RGBS - what to do?

Clearly the only sensible thing is to make my own 129x clone card. This will cost three times as much and take ten times as long as just buying one.
https://www.arcade-projects.com/thr...e-shared-sony-129x-clone-card-for-pvms.17840/

 

[hatmoose]

I still wasnt entirely happy with the way the pot was connected to the board (I had hard-soldered it) - it's much better than the preset resistor, but this part needs to be removed for assembly/disassembly - direct soldering felt like bad electrical juju to me,

And I wanted to be able to see the LED power indicator on the power supply itself. There is an indicator light on the switch, but it's still useful to see the indicator light on the board sometimes too (it pulses if the power is on but there is no load detected for example)

And I still wasnt entirely happy with the cables inside the shell, they were longer than they needed to be.

So to fix the preset resistor/pot thing I used a JST XH header. JST XH compact, good mechanically and rated for a decent amount of current. But the pin pattern is 3 in a straight line, and the pin pattern for the preset resistor on the board is three in a triangle. What to do? Luckily there is an unused mounting hole for the preset resistor, making it 2 in a line and one slighty offset.


So I was able to make a custom JST XH header to fit the slight offset of one of the variable legs and crimp up the wire ends to make a mechanically sound, electrically safe* solution like this. If I ever need to remove the shell for service I can detatach the pot easily without having to dismantle the power supply and desolder it to get it off


Important note on electrical safety - these wires are 20AWG, and the pot is rated for 1/2 watt. The current is 5V at up to 16A.
It would be possible to wire this as a Rheostat. This would be much more mechanically elegant because then I could use a standard 2 pin header with both the pins in a nice straight line (and I would not have to make a custom 3 pin header). But that would also be an electrical safety disaster. The problem with doing this is that the output of a Rheostat is resistance, it controls the voltage by resisting the current - the current, 5v x 16a = 80watts - and this pot is only rated for 1/2 a watt. I'm not sure if the wires would catch fire before the pot did - and I didnt want to find out. The output of a Variable resistor is voltage, it can control the voltage by measuring the difference - in this case 1v, so 1/2 a watt plenty. Incidently this is why pissy little fixed resistors (teeny tiny potentiometers) can go right into the mains side of a circuit with no problems whatsoever, but the dimmer on on your lights (a Rheostat) is huge and hot an buzzes all the time

I also cleaned up the other internal wiring - the best lengths that i could find for the raw wires in this shell was as follows
+5 = 85mm cut
GND = 85mm cut
-5 = 65mm cut
+12 = 65mm cut


This gives finished wire lengths as follows when the connectors are crimped and the socket is assembled
+5 = 65mm finished
GND = 65mm finished
-5 = 45mm finished
+12 = 45mm finished

This is about as short as I can make these with 15AWG silicone wire and still be able to assemble the shell easily. It might be possible to make them slightly shorter with 16AWG which would still be in spec, but I didnt have any 16AWG in silicone and more copper is always better where power is concerned

For the LED indicator on the power supply iteslf I used the same trick as I did for the indicator light on the Supergun - 4mm clear plastic rod cut to length and inserted intop a 3.9mm hole in the case. The rod is held in place with (a lot of) friction. One end touches the indicator LED, the other end sits flush with the case. Then the status of the indicator LED is clearly visible without having a big dangerous hole in the case to look through. If you polish the ends of the rod it's possible to get a crystal clear effect, but this is an indicator LED, not some kind of laser light show, so I left it frosted for a gentle glow


OK, now the power supply really is Done, Done, Done

 

[hatmoose]

I thought I could keep my hands off it, but I could not keep my hands off it.

The nuts are now captive inside the case to remove the temptation of poking a metal screwdriver into a mains device. but now the bottom of the case needs more mechanical strain releif, and I wanted to make sure the head of the nut did not scratch the workbench

So I designed and printed some feet, these serve a dual purpose of hiding the head of the bolt, and stopping the front of the case being subjected to downward force where it was weak


But then the back of the case looked a bit plain, so I designed a back cover to match the aesthetic of the front cover, printing that now

It does not really serve any purpose except to look nice and prevent scratches

 

[hatmoose]

And here it is - done!

Particuarly pleased with how it looks and with how it works, I'll be able to look at it on my workbench with pride for years to come

 

[kikaso]

Really like how this turned out. Love the pinout printed right onto the cover.

 

[hatmoose]

Did some more work on the power supplies recently which I wrote about here
https://www.arcade-projects.com/threads/budget-arcade-power-supplies.10294/page-20#post-290933

Old model Meanwell 125a and 85a power supplies squeak under very low load (NeoGeo) The 2021 version does not squeak under any load. If you have a very low power application (neogeo) and the squeaking bothers you get the newer version
All meanwell power supplies are susceptible to dirty ground. If you are getting diagonal interference consider attaching ground to Frame Reference instead of Earth Reference, or just use a 2 pin power cable.

Physically the 125a is a bit different to the 85a - so I made some changes to the front and back cases to accomodate.

At the back the 125a does have holes for the feet, but the 85a does not - so I re-worked the back cover to make the feet integral - I left the screw holes on the bottom for the 125a if desired, but they are now 100% optional. I also adjusted the clearance slightly, and changed the wording to reflect that only the 125a needs to be manually adjusted for voltage.

At the front the 125a has the LED in a slightly different place to the 85a, so I adjusted the light well position slightly

Original back design, this works for the 125a, but not the 85a (because there are no holes at the back for the feet)


Revised universal case compared to the original


Success! Now fits both 125a and 85a, also requires 2 less parts and 2 less bolts. Unfortunatley there is still one pesky M3 5mm bolt at the front that I cant get rid of, otherwise the whole case could be assembled with M3 16mm bolts.

So back case = done

Front case printing now to confirm that everything is where I want it to be, then I think I'll be done with power supplies.

 

[hatmoose]

Got distracted from the power supplies so decided to do some work on the 4 player adapters instead

There are 120 through-hole pins that need to be soldered for this - by the end of soldering these two my technique was much improved


I'm considerign buying a proper ultrasonic cleaner, doing this with IAP or acetone or circuit board cleaner in a can is getting old...


And working on a case for them now

 

[DeWitt]

Of course! It would be a sad day indeed if I used an enjoyed someone elses hard work, had my fun with it, and didnt contribute my work back for others to use and enjoy too. The entire point of this thread is to share what we learn making these projects

I'm pretty sure this is the final final (of course I was absolutely sure that the previous 7 were also the final one...) - it's printing now - will know in 8 hours

I'll probably publish as follows to thingverse as a remix to the Pacifier case
Top Minigin Advanced 2.5 (probably 2 dozen fixes, added bottons etc)
Bottom Minigun Advanced 2.5 (audio out now fits, adjusted nut size to reduce BOM part count by 1)
Pushbuttons (new)
BOM for nuts/bolts/posts
Will post a link to the thingverse here when it's up

Hej Hej I am following your journey in this thread multiple month now, it’s real interesting thank you very much for sharing I was wondering if you still plan to release the stl files for the supergun case? It would be mega cool!! Thank you very much

 

[hatmoose]

Hej Hej I am following your journey in this thread multiple month now, it’s real interesting thank you very much for sharing I was wondering if you still plan to release the stl files for the supergun case? It would be mega cool!! Thank you very much

Yes, I should - some of my old stuff got taken off thingiverse because it would not slice and I got a bunch of rude comments which impacted my motivation. I've gotten a lot better since then and I'm back into it, nearly done re-drawing everything at a decent level of quality.

In the meantime here is the bottom case for the 4-player adapter I've been working on - the vision is that the Minigun and the 4 player adapter will be a matched set.

 

[DeWitt]

Sounds very cool thank you for your answer! I have the same problem sometimes too, i’m using TinkerCAD... but I have no idea what why this happens.

I am looking forward to your STL file

 

[hatmoose]

Sounds very cool thank you for your answer! I have the same problem sometimes too, i’m using TinkerCAD... but I have no idea what why this happens.

I am looking forward to your STL file

I hear ya - chosing tools is a constant pain. I'm currently making the pinful transition from Sketchup Make to Fusion 360 - i've gone about as far as I can go with Sketchup - but now that I know how to use it everything in Fusion is hard :-/

Got the top of the 4 player caser done too - the first of many test prints is on the printer now.

 

[DeWitt]

I tried Fusion too! It’s very powerful but harder to master then Tinker CAD

 

[hatmoose]

The case for the 4-player adapter is coming along well - printed perfectly first time with no slice errors too. Progress!

I did a lot of work on mechanical strain relief to make sure that inserting the 4-player harness didnt flex the board, and also that the back of the DB15 connectors was supported - I'm going to have to re-draw the minigun case from scratch anyway, so I'll carry the MSR ideas over to that too


I tried to carry the design language over from the minigun to the 4-player adapter - It looks good but it does not look perfect.

My wife kindly pointed out that the glamor side is all no-caps and that needs to be consistent


And the "business" side needs to be all caps to be consistent


I'm still practising my product photography - I still suck, note the coffee mug marks in the background.

 

[hatmoose]

I dont have a PGM 4-player harness, so I dug out the only 34 pin cable that I had. Some very old timers such as myself may recognise this for what it is, an SLI cable off a 3DFX Voodoo 2 from about 1998.


I've been holding on to this; keeping the Voodoo 2 SLI dream alive for a quarter century - It did spark joy when I plugged it in (although not into a voodoo 2) for the very first time. The keying "lump" is on opposite sides for the SLI cable, so I was able to test both normal and goofy orientation.


However; it could spark even MORE joy if it fit absolutely perfectly, so I reworked the top case with a bevel around the slot to accomitate the cable really nicely


I also had an OCD moment when I realised that the 4 player aux harness for this was going to look wrong for CPS1 and CPS2.

Sullins still make a 34 position header for the board - from Franks BOM here
https://www.digikey.com.au/en/produ...nector-solutions/SBH11-PBPC-D17-ST-BK/1990067

But NO-ONE makes a keyed 34 position line shell to plug into it. Lots of keyed cable shells, but no line shells. 20 positon is the largest available, and while it will work fine it wont look good, only half the header will be populated and it wont be keyed
https://nz.mouser.com/ProductDetail...=/ha2pyFaduimesKEy2BcFJ83zRDE1wdq1SaFLPrVmO0=

Clearly that will not do at all - eventually I was able to find this from my firends in china (34 position line shell, keyed with bump) - I'll have to throw the pins away of course, but the shell might be the best thing available.
https://www.aliexpress.com/item/32796001404.html
Will it be delivered? Will it arrive this decade? will it try to kill me? Your guess is as good as mine! I'll let you know in 60 days

Until then recycled floppy drive cables will work just as well - but if I was happy with ugly I would not be doing this...

 

[hatmoose]

Did a bit more work on the power supplies today. I'm pretty pleased, but I was never entirely happy that the mains power cable had to stick out sideways.

I could have put the power inlet on the back, but there was no electrically safe way to run the main voltage lines to the front where the inputs were.
Or I could have turned the whole thing around, put the C14 socket on the face instead of the side, and had all the inputs on the back , but then I would have had to route the +5 + 12 and -5 lines through the power supply so they could come out the front, that would have been silly, and probably dangerous too (although less dangerous than messing with the mains side)
Or I sould have put ALL the inlets, outputs and user interfaces on the back which would have been a 0/10 for ease of use. Things that are a pain to use tend not to get used.
So the arrangement as it stands really is the best trade off of compliance, safety, and functionality.

But it still bugged me that the C13's poke out at right angles


Luckily these exist. It's a right angle adapter for C13-C14


We used to use them all the time when we were putting server hardware into comms racks that were short and didnt have much clearance. These particular ones were left over in my big bag of bits from 20 years ago but I'm sure you can stull buy them somewhere - Shoehorning servers into slightly-too-short racks is a problem that never goes away

The design is actually quite cool. At first glance it's a straight through right angled piece of metal. But the C13 and C14 are not just folded, they are also rotated 180 degrees relative to each other. So the pins have to cross over inside the body to prevent the polarity being swapped. It would have been easy not to rotate the C14 end, but then the C13 line end would be upside down relative to C13 socket end - And the spec for IEC320 C13/C14 says that the lumpy bit is supposed to point down. The engineer that designed these things was probably quite pleased with themselves for getting that part right.

 

[kikaso]

I really like those right angle adapters. Great job on the tidy design of the package.

Would adding a fuse (5A) to the mains power line be overkill? I know cabinets have that on the mains line before it enters the PSU.

 

[hatmoose]

Would adding a fuse (5A) to the mains power line be overkill? I know cabinets have that on the mains line before it enters the PSU.

Yes, very much so. I wrote a long rant about electrical safety on this very topic here. Spoiler alert - Aliexpress stuff is not safe
https://www.arcade-projects.com/threads/budget-arcade-power-supplies.10294/post-291434
But yes, the new ones I have on order are fused (on live) and switched (on live too) so they should be much safer

Final prints of the 4 player case are nearly done now - should have some photos tomorrow

 

[hatmoose]

Been a while since I made a power supply. Had to share this one, extremely pleased with how it came out - will be on its way to its new owner as soon as I make a power cable.



The colour doesn't come out very well in these pictures. its Chinese New Year bright red - quite different to the coca-cola dark red we normally get in the west, looks awesome IMO. The print quality is better than I had any right to expect with an open-frame Cartesian printer (Ender 3) but its about as good as its going to get unless I get a Bambu or a Voron or a K1 or something in the future.

 

[levelupgainz]

Just wanted to say, your write up was great. After screwing up my first attempt soldering THS7374 a year ago I finally got around to trying this again but with the solder paste method and it worked out perfectly. One question I had was on the aliexpress x2.54 crimping tool you bought will that work on the hirose pins also? I'd like to give creating the kick harness a try.