- Thread starter RealMFnG
- Start date
skate323k137
Enlightened
Do you need -5?
My short answer is find a Meanwell rated high enough for current draw on 5V for your use, and with 12v present.
No. Just +5v. This has to work across many different arcade PSU's, not just a Meanwell.
skate323k137
Enlightened
I'm not sure what you mean; are you looking for general advice and not a capable PSU?
Or are you saying you need to add an additional device that needs 4A itself to other JAMMA cabs? Your OP doesn't give me much to work from as far as your end goal.
I want to build a hat for the JAMMAizer that has a header that carries +5v from the JAMMA PSU. I want to ensure the power coming from a JAMMA PSU is stable across the 5v rail to ensure that I am not damaging an RPi or MiSTer that I would be connecting to it. Whether this is done with a regulator or capacitors, that is what I want to achieve. I can only tap into the 5v rail in this instance, so I can't tap into the 12v rail and use a regulator to get it down to 5v.
Every PCB that plugs into a JAMMA harness does this somehow. How do I do this with just the 5v coming off a JAMMA PSU?
Every PCB that plugs into a JAMMA harness does this somehow. How do I do this with just the 5v coming off a JAMMA PSU?
skate323k137
Enlightened
That clears it up, thank you. In that case I'll let others chime in, because my answer would basically be "ensure the PSU has adequate amps available" and I know that isn't particularly helpful.
Edit: I wouldn't assume every JAMMA board has regulation, it's pretty normal for the logic chips to be tied to the VCC rail. That's why the cabs have adjustable supplies.
advans14
Professional
Seems like you need to pass the requirements on the end user to have a properly outputting 5v.
In the case of it being another accessory on top of another, that already has such requirements the most you can do is build a clean proper circuit with good connections.
No one expects a product to work without spark and gas.
In the case of it being another accessory on top of another, that already has such requirements the most you can do is build a clean proper circuit with good connections.
No one expects a product to work without spark and gas.
skate323k137
Enlightened
Thank you, sir.
You're the one asking for help, man.
People should be using adjustable / regulated supplies in a JAMMA cab in the first place. You can't make someone else's PSU have a capable amperage, it simply isn't a thing. It has the balls or it doesn't. A regulator is going to have lower output than input; You can't really regulate 5v with 5v AFAIK, that's why you use regulators to get 5v from 9v or 12v etc; they dissipate excess by design, and at least some of it.
Read here on how to potentially make a shutdown if you go over voltage (note the recommendation to just regulate 5v to 5v using a piece of wire.):
https://electronics.stackexchange.com/questions/355473/regulate-5v-to-5v-with-lm1117
It seems like you're worried about a problem you don't fully understand, so posting captain obvious memes isn't really helping anyone. Put a volt meter on the 5V line if you're that worried. For under current, raspberry pi's can detect undercurrent on their own; not sure about the Mister since I don't own one.
https://pimylifeup.com/raspberry-pi-low-voltage-warning/
After 4000+ posts on this forum, please conclude I have figured out how to calibrate a JAMMA PSU to +5vdc by now and that I would've calibrated the PSU on my JAMMA cabs to 5vdc. I wish to prevent damage to the device. So I am asking how to keep the 5vdc from the JAMMA PSU stable so the device on that +5vdc rail is not damaged.
In any case, I am looking at eFuses. Not sure if that is the best way to achieve this or not, but this a fun thing to ponder.
In any case, I am looking at eFuses. Not sure if that is the best way to achieve this or not, but this a fun thing to ponder.
skate323k137
Enlightened
You use a suitable power supply, or you regulate a higher voltage down to 5V. I know you know how to calibrate your supply, but if anything is obvious here, it's that if you need 4A, your supply needs it available.
An over current protection circuit is doable, but that seems like an abundance of caution at best (which I myself am actually a fan of. My friends call me captain safety).
You're unlikely to regulate a single voltage using that same source, and impossible without some voltage drop. Working with a single voltage that is already regulated, if you can figure out something with a fuse that may be your best bet I guess.
Your assumption that any board plugging into JAMMA regulates or monitors 5V in any way is pretty wrong in my experience. If you can find a game that does it, please show me. I would love to analyze that circuit.
Again, the RPI will visually report undercurrent on its own. It's an annoying problem of its own, which is solved by providing a proper supply or wiring. I ran into it building a BMC64, the PCB traces on the helper board between the power input and pi header were not sufficient, and I had to wire 5v directly to the Pi to make it happy.
I'll agree it's fun to ponder, but I reckon if it were easy or cheap to do it, NAOMIs wouldn't burn out buffer chips like it's their job
Last edited:
