New WG K7000 Help

[Rodimus80]

I just got my hands on a Wells Gardner D7000, and I'm looking for some assistance on how to get my Groovymame connected to it?  I assume I need a power supply and a JAMMA cable?  Thanks in advance!

[Rodimus80]

Here are some images:

https://ibb.co/nnNrP2S
https://ibb.co/j4Z4ydD
https://ibb.co/fXLk6YB
https://ibb.co/F4GhQmk
https://ibb.co/cTbqvjs
https://ibb.co/8YgFJPM
https://ibb.co/yXDsgtX
https://ibb.co/QNkS8dm

[buttersoft]

There must be some specific info on here about the D7000, but assuming for the moment it's a 15kHz monitor (and that your GM setup is outputting 15kHz RGB in some form using crt_emudriver) it will take RGBS at very least, and maybe RGBHV. You need to find the connector for that, and google some more info maybe?

Once you find the header for 15kHz RGBS, you break out your VGA with something like this - https://shorturl.at/jFNY8 and feed it into the D7000's chassis. crt_emudriver can output composite sync if you tell it to. Or if the D7000 takes RGBHV you can just use the VGA signal as it stands.

This will produce a very dim image. Dial the pots up as far as you need to. If they don't go high enough, you need a video amp. You can build a cheap one using a THS7314/7316 or 7374, or buy one. A jpac is one, but only outputs to a jamma edge, so you'll need to break the signel off the jamma edge and get them into the RGBS header on the D7000 chassis. A full jamma cabinet already has this connection in place, of course.

Errr, is that helpful? I'd certainly look around for more info on the monitor, to check it's capabilities and see if you can find the RGBS header.

[Rodimus80]

The K7000 has this molex connector for power. 


What would I need to make it work with this?

[buttersoft]

Errr, ok, the way you are asking this time has me pretty worried you're going to cook yourself I genuinely hope this is not the case.

The molex power plug has three pins. It kinda looks like one is wired to earth/ground to me. In Australia we use green+yellow wiring for mains Earth. This may be different to board ground though, be aware. The other two pins will be live and neutral.

Your isolation transformer will output to two wires, and these will be live and neutral. It normally doesn't matter which way around they connect. The thing is that anything that needs an isolation transformer doesn't require an earth connection, and providing one may be detrimental or dangerous. The reverse, as here, can be dangerous too.

I would wait for someone who knows more about the K7000 or D7000 and how it's meant to be powered. They were really only available in the US? or were they in Europe as well? So i know very little about them.

[Rodimus80]

I was really just asking what the molex connector was called.  I found it I believe.  https://twistedquarter.com/index.php?main_page=product_info&cPath=149&products_id=1025

I got in touch with the seller and his explanation was pretty straight-forward:

There are folks out there that sell the molex connectors, but I usually just strip them and secure them with some good wire nuts.

As for the earth ground coming off the WG, since the transformer is ISO, it's not strictly needed, but some folks wire it down to the filter. Just loosen one of the filter screws, pop a fork connector on the end and connect it to the filter screw and tighten.

[Rodimus80]

Got everything up and running.  Time to clean up.

[Rodimus80]

One more quick question for you guys.  Is it normal for the K7000 to take a few minutes to warm up and show something on the screen?  It took around 10 minutes for the monitor to go from black to clear the moment it was powered on after being powered down all night.

[buttersoft]

A CRT monitor or TV should power up and reach full brightness within ten, maybe twenty seconds at most. Lack of brightness might be caps warming up, i guess. Is the focus ok, or was that what you meant by clear, and the brightness is ok but it takes time to come into focus? Or what?

[Zebidee]

Recap the monitor.

Sounds like at least some electrolytic capacitors are tired. There is only a handful, so grab a "kit" from a reputable supplier. If you don't know how to solder, send the chassis to a local tech to go over it for you.

If you do it yourself, be sure to put them in the right way around.

[Rodimus80]

I bought it a few weeks ago with the understanding it was fully recapped already.  Here's the kicker.  I removed the USB cord from the J-PAC and now the monitor turns right on and the picture comes into focus in about 2-3 minutes.

[Zebidee]

Might just be that, because you had the monitor on recently, something was already "warmed up".

Even so, 2-3 minutes to get a clear picture is still a long time.

If not capacitors, it makes me wonder about the cathode heater circuit. Either that, or the heaters themselves (inside the CRT gun assembly).

I'd want to check the caps myself anyway, especially the main power filter cap(s).

[buttersoft]

I'm still trying to unpack what's happening when you turn the monitor on, though. So, with the j-pac fully connected, with the monitor cold you get a visible picture in a about 15 seconds but is very dim and out of focus, and it gets slowly brighter and comes into focus after... ten minutes or so? And with the J-pac disconnected from USB, but plugged into power, VGA and the jamma edge, from cold the monitor comes on within 15 seconds at full brightness, but out of focus, and it takes another two or three minutes to come into focus properly. Is this all correct?

Is the J-pac new? It would be weird of it to affect things the way you describe even if it's getting old. I've never used one myself, but it has a power plug, a USB plug to talk to a PC, and then the jamma edge? And a VGA port for video input, i guess. If you are convinced the J-Pac is doing something untoward, can you get a meter or even better a scope on the jamma output under the different conditions?

It does sound like caps caps - are they all bright and shiny and new? What brands are they?

Focus drifting is often the sign of a bad flyback, or one that's on the way out. When you power the cab up, and the screen comes into focus over a few minutes, does it stop there, or keep drifting and go out of focus the other way?

[Rodimus80]

I seemed to have solved all the problems but one.  Vertical Hold is not solid.  Jittery in some cases, solid in others.  That has me thinking about my JAMMA harness.  Right now I'm only using the J-PAC for it's 15KHz signal, not for controls or coins.  I ripped out the original power supply and what I assume was a "ground box" that had power from the power supply and all ground wires in the cabinet going to it as well and then out to the electrical outlet.  So basically the only wires on the JAMMA that are plugged into anything are the video lines to the monitor.  My question is does the JAMMA harness need to be grounded even though I only use it for video?

[Zebidee]

You're probably confusing "full ground" of "earth ground" (FG) with your local DC or video ground (GND). These are different things.

You do NOT want to connect FG/earth to the JPAC/JAMMA, so forget that.

GND will already be connected when you plug the JPAC into your computer, and the JPAC connects this to your monitor (probably a black wire).

As for vertical rolling, there are a few possibilities. If you can't adjust it into stability, or it seems to jump around a lot, it could just be a dirty or damaged vertical hold pot. You could spray some deoxit or other electrical lubricant/cleaner and give the pot a few turns to clear any gunk away. That might improve things. If the pot is really bad you could replace it. But then, it might be nothing to do with the pot.

Alternatively, look to see if your monitor has a separate vertical sync input. Check the monitor video connection plug, does it take five wires or does it take six? Five wires is composite sync, six wires is separate H+V. Colours are typically red, green, blue (RGB), black (GND), white (composite/horiontal sync) and yellow (vertical), though your colours might vary.

Point being, JPAC outputs combines the H+V from a computer into composite sync. AFAIK it doesn't output separate vertical sync.

So, if the monitor expects separate sync inputs, you could try connecting the composite sync to the vertical. It'll probably work, monitor can probably tell the difference. The horizontal sync pulses are quite short, whereas the vertical pulses are quite long. Better than nothing at least, and testing it won't blow anything up.

Quick and painless way to connect the syncs would be to get about 2cm of a paperclip (or similar), bend into a U shape, and slip it into the back of the video connector to short H + V signals such that it connects the metal wire crimps and shorts them together. If it doesn't work then it is easily undone.