Power supplies?

[ninjazx7]

Hey guys, I swear this'll be the last question of the day.  

I was wondering what kind of power supply I'll need to run a standard JAMMA cabinet. I'll be using a TV, so I won't need to plug a monitor into it.

Also, do trackballs get plugged into the power supply, or does that run straight off of the PCB?

And finally, do you guys plug the lights behind the marquee into the PS, or does that go right into the wall?

Thanks.

[SNAAAKE]

power supplies are only needed to run the monitor using isolation transformer and to run the PCB.thats about it.you can run other stuff like lights and such using other power source.flusent lights usually have normal cable that goes in your wall.

[ninjazx7]

power supplies are only needed to run the monitor using isolation transformer and to run the PCB.thats about it.you can run other stuff like lights and such using other power source.flusent lights usually have normal cable that goes in your wall.

Thanks. So do I just need a standard 110W power supply with +5v 15A, +12v 2A, -5v 1A  hook ups?

[wee beastie]

Don't skimp on the power supply though.  I've found that some of my jamma boards are sensitive to power supplies.  I used a real jamma arcade power supply from happcontrols.com in my cab for years.  

[SNAAAKE]

what is this so called "REAL powersupply"? .

I thought there was only 1 way and that is to get the onces happ sells.doesnt have to be from happs but same onces right?

[ninjazx7]

wee beastie.... Which PS did you purchase? What are the specs on it?

Thanks.

[ninjazx7]

And just to make sure.....the power supply then just plugs right into the wall, right?

[liche]

Heres some homework for you.  First you need to determine the following:

1.  All devices which require power in your cabinet.
2.  What are the voltage / current requirements for each device you have in your cabinet.  Disregard 115VAC devices as these can be wired directly to your incoming AC power.

FOR EXAMPLE, here is my cabinet requirements:

a.  Wells Arcade Monitor U3100 - 115VAC
b.  PC Computer - 115VAC
c.  Coin slot LED lights - 5VDC @ 30mA
d.  Marquee lamp - 115VAC
e.  Hagstrom Encoder - self-powered through computer
f.  100W (2x50W) Audio Amplifier - 12V @ 10A maximum
g.  Control panel pushbutton lamps - 12V @ 1A maximum

Disregarding the 115VAC items, I see I need the following:

5V @ 30mA minimum
12V @ 11A minimum

So I pick through trash at work and find a 350W computer power supply which outputs 12V @ 12A, 5V @ 15A etc... (also has 3.3V, -5V, -12V but i don't care about those outputs)

Now switching power supplies usually require minimum loading for proper regulation.  I look up datasheet for power supply and minimum load is 5V @ 2A for proper operation.  Since I'm only pulling 30mA from the coin slot LEDs, i need to add on a load.  This is easy.  Just use a nice resistor.

So using ohms law, V=RI, i can determine the size of resistor i need.
R = V/I = 5V/2A = 2.5 ohms
Now i need to determine power rating of resistor
P=V*I= 5 * 2 = 10 watt resistor

So, I need to attach a 2.5 ohm, 10 watt resistor to the output of my 5V for proper regulation.  Easily done.  These type resistors are readily available even at your local radio shack.

Thats it.  Now, once you determine what kind of power / voltages  you need, i'll help you from there.

[liche]

Here is a picture of my converted power supply.

I cut most of the output wires and wired the +5V, +12V directly to the terminal board I attached to the top of the supply.  The gold thing is a 50W, 2.49 ohm resistor which puts a 2A minimum load on the +5V which is required for proper regulation and operation of the power supply.

http://users.snip.net/~liche/powersupply01.jpg

[cdbrown]

The picture doesn't work  

[liche]

Sorry.  Picture should work now.

[wee beastie]

snaake,  by real power supply, I meant one that is meant for an arcade cabinet.  I used a crappy PC powersupply on my jamma boards and it would cause some of my games to lock up.  I asked one of the electrical engineering professors here at UVA, and they seemed to believe that cheap pc power supplies are prone to "power spikes."  (I don't know much about electronics, so I can't provide you with details).  Anyway, all I meant was, buying a cheap pc power supply is not the best route to go....

[Analog-X]

Wow that was a refresher course for Electronics
 
What is the name of that Golden thing on your PowerSupply?

[liche]

>I used a crappy PC powersupply on my jamma boards and >it would cause some of my games to lock up.  I asked one >of the electrical engineering professors here at UVA, and >they seemed to believe that cheap pc power supplies  >prone to "power spikes."

Thats probably the problem.  Although professors are very knowledgeable when it comes to theoretical information, when it comes to practical knowledge they are usually pretty lacking, as most have zero experience working in industry and in the real world.

The problem is not so much "power spikes" as you call them, but more likely a problem of output ripple or the fact that you didn't preload your cheap pc power supply.  It definitely not power spikes (peak voltage transients) as this would definitely affect the sensitive power equipment they are driving.  I have an arcade power supply and this particular one is designed with a switching topology that doesn't require a minimum load.  Perhaps, you never put a preload on your pc power supply therefore weren't getting the proper regulation.

Also, output ripple is a real problem with all switching power supplies.  Linear supplies have very clean outputs, but the drawback to them is they are much larger, much heavier (big transformer), and more expensive.  If you have a multimeter, you can measure the output ripple simply by switching the meter to Volts AC and seeing what the output voltage is.  

And with output ripple, your JAMMA boards probably do not have enough filtering on them (capacitors in the simplest sense) to provide the filtering necessary for those boards.  

Another problem is grounding.  YOU NEED TO PROVIDE a good ground path between your computer and the JAMMA card, and the power supply powering the JAMMA board, otherwise you could have all kinds of problems.




 (I don't know much about electronics, so I can't provide you with details).  Anyway, all I meant was, buying a cheap pc power supply is not the best route to go....

[liche]

BTW, you could always build your own linear power supply as well.  Easy to make, not expensive, and you'd probably have fun doing it...

A good book which is readily available (more practical knowledge than theoretical), is

BUILDING POWER SUPPLIES which can be purchased at
any local radio shack for about $7.00 i think.

Yeah, it may be embarassing to own one of those kinds of books (from Radio Shack), but i know many a power engineer (including myself) that keep these things handy just because they are so stupidly simple.

[wee beastie]

thanks for clarifying liche.  I think he "dumbed down" his response for me because I was a econ/finance student, and not an engineering major.