Monitor on test bench - setup questions

[ChadTower]

What is the optimal way to do this?  I have always worked on them in the cab.  I'd like to work on them independently from the cab's power circuit from now on.

The one I'm working on right now is a motorola XM501.  Schematics indicate it takes 110v straight in (it also seems to route audio from the boards to the speakers).  Am I correct in assuming that I can give it any 110v source?  I have a couple of test bench power supplies that I haven't figured out how to use yet.

As for video signal, since this one takes b/w composite, and I've read that you can take the rca composite out from any standard video source... am I correct in that to do this I would snip off the ends of an RCA cable - plug outer jacket to video ground, inner prong to video in?

[D_Zoot]

What is the optimal way to do this?  I have always worked on them in the cab.  I'd like to work on them independently from the cab's power circuit from now on.

Best to rig up an isolation transformer for bench use.  Line voltage -> isolation -> monitor,  just like you would in a cab.   Even if a specific monitor doesn't require isolation,  for safety reasons I always use isolation on the bench.    I built a little rig for it,  a fused, switched isolation transformer made out of part from old cabs.  I built a series of connector adapters for the output so I can plug in virtually any monitor without additional rigging.

As for video signal, since this one takes b/w composite, and I've read that you can take the rca composite out from any standard video source... am I correct in that to do this I would snip off the ends of an RCA cable - plug outer jacket to video ground, inner prong to video in?

Yup!


Regards,
D

[ChadTower]

[quote author=ChadT
Best to rig up an isolation transformer for bench use.  Line voltage -> isolation -> monitor,  just like you would in a cab.   Even if a specific monitor doesn't require isolation,  for safety reasons I always use isolation on the bench.    I built a little rig for it,  a fused, switched isolation transformer made out of part from old cabs.  I built a series of connector adapters for the output so I can plug in virtually any monitor without additional rigging.

Thanks... I will double check, as I'm new to this, but I think this particular monitor takes its power in before the iso transformer, straight from main.  There is a transformer right on the monitor.  I'm still learning to read schematics, so at this point I'm using that in combination with physically tracing the wires to doublecheck.

[D_Zoot]

It probably doesn't "need" one, it's been a long time since I've worked on a Motorola so I don't recall.

But my suggestion for isolation has more to do with your safety than the monitors requirements.   By isolating the monitor you are ensuring there won't be anything on the monitor chassis hot relative to earth ground.    Isolation of the line voltage in equipment on a workbench is standard safety practice, has been for years.

D

[ChadTower]

Good to know.  I bet one of those test power supplies I have sitting around would work nicely.  I have a bunch of older test bench equipment I haven't figured out how to use yet.  It's about time to do that.  I hadn't done it in the past because my test bench wasn't powered by a good grounded circuit anyway - it was all a wonky basement circuit I didn't want to push very far.  It now has a new 20A circuit that was installed this month, so it's time to rock and roll.   

[Ken Layton]

What is the optimal way to do this?  I have always worked on them in the cab.  I'd like to work on them independently from the cab's power circuit from now on.

The one I'm working on right now is a motorola XM501.  Schematics indicate it takes 110v straight in (it also seems to route audio from the boards to the speakers).  Am I correct in assuming that I can give it any 110v source?  I have a couple of test bench power supplies that I haven't figured out how to use yet.

As for video signal, since this one takes b/w composite, and I've read that you can take the rca composite out from any standard video source... am I correct in that to do this I would snip off the ends of an RCA cable - plug outer jacket to video ground, inner prong to video in?

The black & white monitors (Motorola and Wells-Gardner) already have a builtin power transformer and don't need an isolation transformer. Just give it 120 volts AC. You don't even need to put a fuse in line with the power cord you make up since the monitor already is protected by fuses. It would be a good idea to make a power cord with an inline on-off switch though.

This series of monitor has a builtin +5 volt linear (analog) power supply to run the gameboard. Some versions also have a builtin optional amplifier board.

Yes it takes standard NTSC composite video input. I made up a cord years ago with a common RCA plug on it. Your wiring assumption is correct. You can feed it the video output from VCR's, DVD's, security cameras, etc.

Here's the pinout of the connector when looking at the rear of the monitor:

1   4   7   10

2   5   8   11

3   6   9   12

Pin 1 is video signal
Pin 2 is video ground (shield)
Pin 3 is common ground
Pin 4 is audio signal input
Pin 5 is output to speaker - terminal
Pin 6 is +5 volts output to gameboard
Pin 7 is AC power cord ground
Pin 8 is output to speaker + terminal
Pin 9 is AC power input neutral
Pin 10 is AC power input hot
Pin 11 is not used
Pin 12 is not used

Pins 3 and 4 are your audio input like from a cd player or any line level audio signal.

[ChadTower]

Awesome, thanks Ken.  If I understand that correctly, I should be able to use a PC power cord to do this:

pin 9:  white
pin 10:  black
pin 7:  green

Then the video comes in:

pin 1:  signal (inner prong RCA)
pin 2:  video ground (outer conductor RCA)

I should be able to use an outlet strip temporarily as an inline on-off switch.

The best way I can think of to make these inputs would be to actually strip/pin to match an RCA cable and a PC power cord... I want to repin all of the internal connectors anyway on the game so ordering up a bunch shouldn't be a problem.

[Ken Layton]

Yes to all.

These monitors use AMP brand Universal Mate n Lock connectors.

If I remember correctly, get Mouser # 571-14807080 housing (12 pin) and 571-3505471 pins

[ChadTower]

Yes to all.

These monitors use AMP brand Universal Mate n Lock connectors.

If I remember correctly, get Mouser # 571-14807080 housing (12 pin) and 571-3505471 pins

Awesome again, Ken.  Thank you.   I'll order it all up today along with some extras.

I'm always amazed at how valuable a resource this place is to people who are close but not quite where they need to be.


EDIT:

For future reference, the female connector is 571-14807090 and the female pin is 571-3505501.

[ChadTower]

Just for a bit more reference:

This game, Tank II, does not use the monitor supplied +5v for anything other than the coin counter.