Main > Monitor/Video Forum
New WG K7000 Help
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.