(Topic ID: 148809)

Adding an external 5v power supply for mods

By jsa

3 years ago

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  • 36 posts
  • 12 Pinsiders participating
  • Latest reply 3 years ago by toyotaboy
  • Topic is favorited by 12 Pinsiders


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#1 3 years ago

Hey all, looking for some advice. I have a ToM, and I'm thinking of adding an external 5V power supply for mods (rather than take the power off my WPC-89 power driver board). It takes line power 120v in and in theory, outputs 5V appropriate for various things. My question is, has anyone done this, and if so, any thoughts on what would be the most elegant way to grab power, in terms of being properly fused?

One thought I had was using the maintenance outlet to the back box, or a second power cord. Here's what I'm thinking of installing:


Thanks all!

#6 3 years ago
Quoted from GRUMPY:

The p/s you have there is fine but the suzo wayout ^^^^ has is better because of the 12 volt section can be used for leds strips and other 12 volt mods. I rewire the service outlet on my pins so that the outlet turns on with the power switch.

Can you link to the Suzo PS you're referring to? I can't find any reference to it.

Also, you mention re-wiring the power supply to turn on with the power switch. Any tips before attempting that myself?

#9 3 years ago
Quoted from wayout440:

Search "happ power" on ebay....many there. I just pick one that is close to my geographical location for cheap shipping and make sure they have a clean track record for Ebay sales.
Rewire basically like diagram below. You can use an AC plug into the service outlet for a temporary mod or hard wire it for something more permanent. Some games might not have a three prong outlet for the service outlet, or even a three prong AC power cord. For safety, adding the third condutor (green) is highly recommended.

That's perfect, thank you!

#10 3 years ago
Quoted from wayout440:

For safety, adding the third condutor (green) is highly recommended.

If the power supply delivers 5V/5A, and a mod (like in my case, the Tiger Saw motor mod for Theatre of Magic) requires far less current, does that mean I should install a current-limiting resistor? I'm a little backwards on electronics.

#13 3 years ago
Quoted from markmon:

No. The mod will take what it needs.

Quoted from wayout440:

...or hard wire it for something more permanent.

Do you guys recommend wiring the power supply after the fuse?

#15 3 years ago
Quoted from GRUMPY:

Either way it wont matter. I you like I can take a pic of how I rewired my No Fear service outlet to be on only when the game is on. It will have to be later as I'm still at work.

Couldn't hurt, but don't work too hard on it, I think I'm ready to go!

#20 3 years ago

Here's a real electronic stupid question: If your mod takes on/off signal from the power driver board, and you're using an external power supply, what do you do with the negative lead off the power supply, wire to ground?

#22 3 years ago
Quoted from G-P-E:

Tie the grounds together. NEVER connect the various power signals (e.g. +5V and +12V) to internal power, keep them isolated.

I'm not sure I understand. Tie which grounds together? The power supply is grounded to the same ground the machine's power unit uses. I'm trying to figure out how to complete the circuit. Normally, this mod I'm using takes the red lead to 5V on the power driver board and the black lead to one of the pins reserved for the control signal on the machine. Now, since I'm using external power, my red lead comes from the positive on the power supply, and the black lead still goes to the control signal. I need to wire the negative lead of the power supply...somewhere, to complete the circuit, correct?

#24 3 years ago
Quoted from GRUMPY:

Do you mean a negative signal and positive from your new power supply? If yes then good to go.

The mod works by interrupting the black/negative from the mod to the power driver board. If I connected the negative lead directly to the new power supply, it would be always on. I assume, therefore, I should wire the power supply's negative lead to ground...?

#27 3 years ago
Quoted from wayout440:

If I am understanding, you are trying to use the games control signal/driver to turn on the mod? If so, you should use a relay to turn on the mod. You will tie the ground from the mod supply to the game ground, but this is a safety ground only. you can't tie a negative voltage from your mod power supply back into your game supply.

Ok, my apologies, I don't think I'm explaining this right.

The mod in question is a motor that turns when the software in the game tells it to. Unlike typical mods, this one was a feature of the game that was originally cut from production because of costs, and they re-added it later. The actual game software tells the motor to spin at certain times, using one of the previously unused pins on the power driver board

For this to work, the mod typically gets it's power from the game's internal 5v power, and the negative (black) wire is tied back to the game's power driver board on a specific pin that completes the circuit when the game software tells the motor to run.

Since I'm moving this to an external power supply, my 5v (red) positive lead is coming from the new power supply. I still need the mod's negative lead to tie back to the game power driver board because the game still tells the mod when to spin. Therefore, the mod's black wire is run to J125 pin 3 on this WPC 89 power driver board (ToM).

However, that leaves me without running the negative (Black) lead from the power supply to anywhere. I assumed I should run it to ground, because if I don't run it, the circuit isn't complete and the mod won't spin, at least I think so.

I ran it to ground and it works, I'm just wondering if this is the right way to do it?

#30 3 years ago
Quoted from GRUMPY:

He wants to make sure your you don't put the positives voltages together. Like connecting new power supply 5 volts to the game 5 volts on the driver board. This is bad!

Awesome, thanks.

Got it, don't cross the streams. Right. That's bad. Okay. All right. Important safety tip. Thanks, Egon.


#35 3 years ago

I did use a grounded cord. I'm a little obsessive so I probably over-did it, but that's just me. It's all working quite nicely now. Thanks everyone!

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