Think I blew a cap?

[tokyogameaction]

Hey Everyone!

It's been a while since I posted here, been kinda out of the arcade scene recently. This week a friend of mine bought a Dance Dacne Revolution machine with a 27" Panasonic CRT arcade monitor in it. The machine arrived non-grounded and loved to electrocute us on touch, so I decided I wanted to tackle that first.

I took a piece of wire and ran it from the grounding pin on the plug and ran it to a screw placed isolated in the wood of the machine. I considered this my main grounding point (GP). From the GP I ran 3 lengths of wire. The first length went through the machine, and to the pads. I put molexes where the wire tube comes undone, then i ran the wire to a standard screw that went into the metal of the pads on each pad.

The second wire I ran from the GP went to both the metal casing around the audio amplifier and then to the metal casing around the machine's PCB with a molex in between the two in case I wanted to remove the PCB.

The third wire I ran up the machine (behind but not touching the monitor) and into the marquee area. I screwed this wire just to a piece of wood as I hadn't figured out what I'm gonna ground up there.

As soon as I plugged the machine in I heard a spark from the monitor area and smelled burning. When the machine was powered on the monitor was white with an awkward shaped jagged black blob in the middle. I removed the ground wire from the cord and tried again and this time the machine booted, but now the monitor was acting a little weird. The monitor was kind of like when you film a monitor, with the black horizontal lines scrolling vertically, except instead of black lines they were bars of noise.

I really have no idea where the ground went wrong, or what I did to the monitor, but any help would be appreciated.

-Anthony

[Kevin Mullins]

Look for a large cap in the power supply section of the monitor usually near where the power for the monitor comes in at.

Did it "pop"?

Need to verify make and model of the monitor though.
I'm not familiar with any Panasonic models..... unless that's just the tube manufacturer you're looking at. Maybe someone else knows otherwise.

[SirPeale]

DDR machines have some funky monitors in them sometimes.  Post a picture.

[Ken Layton]

All the DDR machines I've worked on had either Wells-Gardner 9200 or Neotec monitors in them.

Panasonic does NOT make arcade monitors.

[MonMotha]

My experience with a couple friends' DDR machines is that they love to have "hot" power grounds (i.e. the black wire; not to be confused with earth ground).  I have not yet isolated the cause, but I've been zapped several times by the stupid coin return lamp.  At first, I thought they may be playing the trick of using a non-isolated monitor with isolated power supplies, resulting in a hot power ground, but the monitor appears to use a SMPS, which should isolate.  I had wondered if this was a universal phenomenon with these cabinets - seems to be.  I haven't yet confirmed if any other Bemani cabinets do this, though some have reported ground issues in Guitar Freaks.

Your monitor sounds like it may be a replacement.  The original is a Toshiba branded monitor for Japanese cabinets; Korean and USA originated cabinets have a different monitor, different cabinet arrangement (but then you probably knew that), and don't seem to have the nasty grounding issues.  Tube on these Toshiba monitors is often a Mitsubishi.  Very Japanese cabinets, as you might expect.  Sounds like Ken has also mostly seen replacement monitors (or perhaps non-Japanese cabinets).  Many are old enough that the monitors have failed in one way or another and have been replaced at this point.

What you may have done is created a ground loop through a part of the monitor using video signal ground as the path from power common to earth.  That could certainly cause various pieces of the input side of the monitor to blow up.

The Japanese DDR cabinets I've seen have all had most of the externally touchable metal surfaces (stage and coin door, mostly) meticulously tied to earth ground via dedicated lines like you'd expect.  However, power common seemed to float to something that hurts, and you can pull enough current off of it to trip the breaker on the power supply box.  It sounds like your machine was missing the earth grounds and had a fault somewhere from power common to those metal surfaces. I have tripped that breaker out by hooking up a o'scope ground clip to power common.  This suggests it's not just a floating line bridged with a capacitive divider in a SMPS like you get if you fail to ground a PC power supply.

The only parts of the cabinet that run on AC are the power supplies, monitor, the marquee lamp, and the CCFL transformer.  Everything else is DC from the big box 'o power.  I guess a useful thing may be to isolate each of those (connectivity wise, not using a iso xfmr) and see which one has the hot "ground".  Inspecting the wiring inside the box 'o power may also be useful.  Remember that the Japanese usually lack grounded and even polarized outlets, so they don't so much care about how they wire things up.  Perhaps they tied the (black) AC line to the (black) power common and called it good

[grantspain]

depends on the ddr make,konami use sanwa pm1475 monitors
obviously was not a ground you picked up
sounds like you have killed the mains smoothing cap on the chassis

[tokyogameaction]

I should specify that this is one of those shotty built Korean Cabs and not an official Japanese cab. Also, in reference to me blowing out the smoothing cap. Is that something I can easily replace myself with some soldering?

[grantspain]

so is the make andamiro then?
take a photo of the chassis and the part thats exploded,then post the photo here

[tokyogameaction]

I'm gonna try to take photos today. The Korean DDR Machines look almost hand made, they are very poorly designed, but the pads are identical to the Japanese cabs and the exterior looks almost spot on so this was all I needed.

Andamiro makes 'Pump It Up' which is a Korean 5-Panel dance game.

[MonMotha]

Ah, I've never been inside one of the Korean ones other than to swap a CD-ROM drive.  I'm told they are constructed like the original 1st and 2nd Mix DDR JP cabinets (before they went to the vertical shelf design).  My (limited) experience has been that they don't suffer the same nasty grounding issues that the Japanese ones do.

As for Andamiro, yes they do make PIU.  PIU is far more prevalent in Korea than DDR (DDR never really took off).  PIU machines (made in Korea) are also sold in the USA.  They aren't as solid as DDR machines, but they seem well built otherwise.  They tend to use Kortek monitors these days.  Machining accuracy can vary from rather good (especially the new SXes) to only OK (mine requires some care when choosing where to put corner brackets to make sure it'll line up with the holes well enough, but otherwise plays fine).  Power distribution seems clean in them.