Pacman c/t: G07 likes to hula/degauss needed

pmichelsen

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Alright, I have a Pacman c/t with a G07 in it and I'm having some issues with the G07.

The G07 thinks we are at a luau and I can't get it to degauss.

Here is what I have done so far:
-Rebuilt G07 (caps, fly, Hot, Regulator, Width Coil, fuses)
-New edge connector
-New 4 position fuse holder (going to replace the 3 position this weekend wasn't in Bob's kit)

I have tried the drill method to degauss this bitch and I can get it to look good but once the drill is gone it goes right back to how it was. Also this monitor isn't the original to the game and when they swapped it in they just used the Pac plug in the G07 plug and it can go either way, does this matter? I would think that is does but I am not sure what the right way would be on the G07 side.

As for the hula, I'm at a loss. I will be working on this beast this weekend to try and have it ready for my friend by next week, so any advice is greatly appreciated.
 
Two things. One, the degauss circuit in a monitor is really, really simple. It's just a thermistor and the coil - easy enough to check with the meter to see if anything is open.

Secondly, it's common for monitors to need an external degauss from a strong source - a drill may not be enough.

Also, remember that if you degauss it when the lid is open, then shut it, you'll screw up the colors again. The game needs to be degaussed/powered on with the monitor in the position it needs to be in. This question comes up a lot because people will have the lid open to check out a game, power it up, find out it's working and the picture looks good, shut the lid, and now all of a sudden the colors are screwed up. The monitor's relation to the earth's magnetic field should not be changed...

-Ian
 
What exactly do you check with a meter? I was worried that the drill might not be enough. Why is it that a monitor that had no issues before a rebuild needs degaussing after?
 
You moved the monitor, right?

Evey time you move a CRT, the earth's magnetic field affects it differently. Because of this, all color monitors have a built in degauss circuit. If something broke in the degauss circuit, so it's no longer working, then it won't clean it up every time you turn the monitor on from cold.

It's also possible that the tube somehow got exposed to a strong enough magnetic field that the built in degaussing coil can't clean it up.

You did remember to reconnect the degaussing coil when you rebuilt the monitor, right?

There is only one component in the degauss circuit - the thermistor/posistor, R901. Check it with the meter. Also check the degaussing coil itself, and the solder joints to it.

-Ian
 
Actually I haven't moved the monitor at all :D, well I moved the chassis. But I see your point, I will check the whole degauss circuit and see if anything looks funky and meter that bitch.

Anyone have any thought on the wave?
 
does your cab have the metal plate covering the power brick?

you shouldn't be able to see any of your power brick.
 
It does not, but it also doesn't look like there was ever anything there. No extra holes or anything, I will post up some pictures of everything tomorrow.
 
I have capped a monitor chassis only to find out that the cap(s) I put in were not good.
To see the problem is to know the repair needed. Youtube would be a good place to post a video of the monitor while it's having a problem.
 
Alright, I unplugged the video cable, turned up the brightness and the hula is still there. I also plugged in a different monitor (WG KXXXX) and there was no hula on that one.

I metered the degaussing coil and everything appears to be good there.

Any other recommendations? I will take some pictures tomorrow but would love to hear any other ideas. Worst case scenario I will swap in a different monitor before I give it to my friend.
 
I unplugged the degaussing coil and that had no change on the hula. I also checked the B+ and it appeared to be around 97.7 and the pot was already pegged, so obviously something needs to be replaced there.

Here is a picture of the wave:

IMG_0356.jpg
 
I unplugged the degaussing coil and that had no change on the hula. I also checked the B+ and it appeared to be around 97.7 and the pot was already pegged, so obviously something needs to be replaced there.

For anyone who reads this thread, later, I have highlighted a VERY important part.

This should have been done FIRST. Proper operating voltage is critical to a monitors operation.

Not that I'm knocking pmichelsen; it's just something that he did not realize.

Check the voltage regulator, R908, X901, x902.
 
R908 is a resistor; unsolder one leg, and check it's value. If it's open, replace it. If it deviates widely from it's value, replace it. Heck; since you're going to unsolder one leg, unsolder them both and just replace it. If you have it. Most cap kits (including mine) come with this, standard, as it's a high-failure part.

X901, X902: remove them from the board, and follow this:

http://www.youtube.com/watch?v=YsJXFLnA62s

Voltage regulator is similar:

http://www.youtube.com/watch?v=REW2lF0sb74
 
This may be a longshot, but if your B+ pot is turned up all the way and you only get 97 volts, check to make sure the game is getting enough power from the outlet. I worked on a Pac for someone that had the same problem. The game was at their shop and I finally checked the voltage in to the game from the outlet and it was low. They were running too many things but not enough to blow the breaker. It's worth a look.
 
Thanks for the heads up, I will look into this. I hope this isn't the issue since I ran all of the wiring in my shop and it is the only thing plugged in to a dedicated 20amp circuit. But you never know.
 
How do I check the degaussing circuit? Is it a continuity check or votage? I'm new and learning the monitor side of things.
 
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