AC Wiring Question

[DashRendar]

I checked the Wiki, but didn't find the answer I was looking for...

Scenario:

I have a Midway cab that has NFL Blitz 99 in it.  Everything is hooked up in it and it works fine.  My goal is to convert it to MAME, while using the arcade monitor inside it. 

So I need power still to the monitor and marquee, but need to disconnect the power to everything else (PCB, speakers, etc).



I assume I'll still use the cab's power switch to turn on the monitor and marquee, but will use the PC's switch to turn that on (until I can figure out a better way to do that all at once).

For now, I'll be leaving the PCB and hard drive in the cab.  But I need to disconnect them so they don't power up.

Is it better to disconnect the power at the cab's PSU, or at the boards themselves?  And is there any issues I need to be aware of in terms of wattage changing by disconnecting these?

I want to make sure this is up to code and that I won't have a Tesla coil inside the cab, hehe.   

[Ed_McCarron]

Is it better to disconnect the power at the cab's PSU, or at the boards themselves?  And is there any issues I need to be aware of in terms of wattage changing by disconnecting these?

No electrical difference, however, if you disconnect at the PSU you won't have live wires flopping around the cabinet.  Probably a touch safer in the long run.

Can you just pull the fuse for the existing PSU in the cab?  Are there multiple fuses for the marquee light and monitor?  This'd be my choice, if possible.  Why power up the PSU if you don't need it?

The wattage shouldn't be an issue.  The PCB is a small load compared to the monitor.

[DashRendar]

I haven't seen anything in terms of fuses in the PSU, but I haven't really looked closely at it yet.

Still learning here, but would the AC be wired as-

 _____            ________             ________
| PSU |-------| Flyback |--------| Monitor |
|____ |          |_______|            |_______|

[Ed_McCarron]

Probably not.  If theres an isolation transformer, power typically comes thru it to the psu and the monitor.

Looking at the pic, you could probably take the purple wires to the left of the power supply and disconnect them.  Tape them up real well, and you've just disabled the power supply without needing to unplug anything.

The monitor and marquee should still power up fine.

There will be 120v on the wires under the tape, so be careful.  You may want to snip them and put wire nuts on or something.

What does the label say where the purple wires are landed?

[Ed_McCarron]

This might clarify.  I'm not 100% familiar with that particular cab, so I've made some assumptions.

[DashRendar]

Whoops- I meant isolation transformer, not flyback transformer.  But you understood what I meant. 

Here's a closer look at the PSU (sorry for it being sideways):

[Ed_McCarron]

Yup.  Turn off the power, disconnect and safe off those two purple wires landed on AC/L and AC/N and you will have disabled all low voltage.

AC/L = Line, AC/N = Neutral.

[RayB]

Dash, you've got it all wrong. The Monitor does NOT get its power from the power supply!

AC from wall -> to power switch -> Isolation transformer - > Monitor
                                                 -> Marquee light
                                                 -> DC power suppy -> game board -> controls

The power supply is strictly for converting AC to DC and powering the DC stuff like the game board and any lightbulbs that may be lighting the coin door.

[Ed_McCarron]

Dash, you've got it all wrong. The Monitor does NOT get its power from the power supply!

AC from wall -> to power switch -> Isolation transformer - > Monitor
                                                 -> Marquee light
                                                 -> DC power suppy -> game board -> controls

The power supply is strictly for converting AC to DC and powering the DC stuff like the game board and any lightbulbs that may be lighting the coin door.

Yeah, I gave up on his ascii schematic.  I was trying to interpret it as the isolation xformer in the middle, feeding power left and right, with no input shown.  I was probably being generous.

[DashRendar]

Well, obviously I meant that the AC power fed into the power supply in my ASCII diagram.  I didn't assume it was self-contained power.   

But that's good to know.  The iso transformer will have to remain hooked up for the monitor and marquee light to work.

From reading your flowchart, I should be able to disconnect the PSU completely from the equation.

[CheffoJeffo]

Well, obviously I meant that the AC power fed into the power supply in my ASCII diagram.  I didn't assume it was self-contained power.   

This is one of those times where folks worry about giving advice because it doesn't look like you know what you are really doing, then they give advice and then magic smoke is released everywhere.

If it *was* obvious to you , the you should have made it obvious in your diagram. I would say that the majority of new folks seem to think that the AC power for the monitor comes from the switching PS.

The definitive wiring page is still Bob's:

http://www.therealbobroberts.net/acwiring.html

Before giving specific advice, I would prefer to see a clear picture of how things are wired around the ISO, although I think Ed is right.



Perhaps the most important question has yet to be asked ... how are you planning to interface the controls and monitor to your PC ?

 

[DashRendar]

My apologies if I wasn't specific.  There's no "magic smoke" intended, heh.

To be clear- I assumed the AC power fed into the PSU (as it does in a PC), rather than anything else (the isolation transformer).  I'm not currently home, but have a couple photos I took of the inside to go off of.  Thanks to the advice, I see that's not the case.

This is my first cab, but I have a very strong technical background and do pretty good with electronics.  I'm also cautious.  This is why I came here looking for answers on the forums and wiki rather than attempting to unplug things and make mistakes.

Regarding the controls- I have 2 U360s which will connect up to the USB ports on the PC.  I have the I/O harnesses that Andy makes to connect the buttons directly to the joysticks.

Regarding the monitor hookup- I have an ArcadeVGA 2 that I'm going to be using.  Picked up the VGA adapter to connect to the end of the video cable to interface with the Arcade VGA.

[CheffoJeffo]

FWIW, that was a harsher reply than I intended and caution is advised in order to protect the stuff that you have spent money on (be it in the old cab or shiny new stuff). I expect that Ed is correct with his assessment, although before you go cutting anything, I always like keeping my converted cabs as JAMMA to provide for nice, easy interfacing of the video circuitry.

 

[DashRendar]

Cheffo: No worries, I understand.  It actually concerns me sometimes that brand new folks get into this hobby, messing with potentially lethal currents without realizing the danger.

Ed: It's a JAMMA cab, but I'm not using a JPAC.  Instead I'm using Ultimarc 360s.  The cab has 49-way sticks which I'd rather not mess with.

I have been tempted to leave the PCB etc still intact though, for the odd times I'd like to play Blitz '99.  I won't be able to afford a rig that can emulate that in a playable state for a while, and I KNOW my brother and father-in-law love that game!

It'll be a PITA to switch it back, but not impossible.   

By the way, thanks everyone for the advice.  I do appreciate it.

[RayB]

My apologies if I wasn't specific.  There's no "magic smoke" intended, heh.

Magic smoke is what comes out of burnt up equipment when power is wrongly wired.

To be clear- I assumed the AC power fed into the PSU (as it does in a PC), rather than anything else (the isolation transformer).  I'm not currently home, but have a couple photos I took of the inside to go off of.  Thanks to the advice, I see that's not the case.

Again, you have to think deeper: Even with a PC, where does the PC's monitor get power from? Not from the PC's power supply. But I think you get it by now...

Yeah, bear in mind I only addressed turning off the power supply like you asked in the first post.  If it is a jamma cab, then you might want to leave the PS connected to power up a JPAC or the like.

More misinformation. The JPAC does not use power from the power supply. It's powered off the PC's keyboard port.

[Ed_McCarron]

Yeah, bear in mind I only addressed turning off the power supply like you asked in the first post.  If it is a jamma cab, then you might want to leave the PS connected to power up a JPAC or the like.

More misinformation. The JPAC does not use power from the power supply. It's powered off the PC's keyboard port.

D'oh.  Swore it got its power from the harness.  Disregard.