Pac-Man + K7200 = scrambled no sync goodness

mecha

Well-known member
Joined
Apr 19, 2007
Messages
24,331
Reaction score
7,036
Location
MKE, Wisconsin
well, the banquet hall I had my wedding at last month asked me to fix their Pac-Man, which originally had a monitor that wouldn't turn on. upon inspection whatever it shipped with was replaced by a K7200 (I forget which exact model it was)

after I tore the whole game apart I found that there was a loose pin in the AC connector and sure enough, the monitor fired up. however in the process of pulling the monitor, like a dipshit I forgot to unplug the signal connectors and broke a wire off on the sync connector.

I assumed fixing the sync issue would be as simple as crimping a new pin on and sliding it in, but I still have no sync.

I'm not knowledgeable about Pac-Man, this is my first time putzing with one of them, but according to the pinout there's only a single sync wire, but on the other side I have 3 orange/red wires that plug there... so does it run on negative composite sync or is it positive or what's the deal?

Wells doesn't have a manual posted for the K7200 so I went off the K7000 one for the header pinouts and this thing was wired to the negatives on both the -H and -V.

the people I've talked to about it have no knowledge of the game's operation state before the monitor not turning on issue arose, so I can't tell if it worked this way before or not.

I played with both the H-Hold and V-Hold pots to no avail, this thing just has no sync. wiggling the edge connector wires resulted in what appeared to be primary colors going in and out, which I could tell from the red disappearing from the scrambled mess.

so anyone out there just tell me what it'll take to make it work on a K7200.

thanks. :)
 
Do not connect the -V sync. If you have problems with getting the sync locked (and the caps are good), look at the ground wire...
 
oh, another good point, does the ground wire go on the positive side or the negative side?

cause there's 2 separate ground pins, if you use negative sync, do you plug into that ground only, or does it go on both?
 
Ground shouldn't matter, they're interconnected on the circuit board.
(one and the same ground)

Wells doesn't have a manual posted for the K7200 so I went off the K7000 one for the header pinouts and this thing was wired to the negatives on both the -H and -V.

I'm not super familiar with Pac's, but I thought they were negative composite sync.
If yours has two sync wires, they would go to the -H and _V like you described. But look down the line on the video input harness for a small jumper/loop connector to tie the two together. (not sure if Pac's have one)
 
wiggling the edge connector wires resulted in what appeared to be primary colors going in and out, which I could tell from the red disappearing from the scrambled mess.

On the game pcb edge connector or the header pins on the monitor ?
(I initially though solder joints is why I asked)
 
ah, no, it was when I was wiggling the edge connector. was wondering if it was a loose connection there causing the sync issue and I just happened to see red disappear in the picture, and then at one point it was all blue.

the pinout calls for what appears to be negative composite sync, however at the end where all the monitor wiring plugs into the signal header, for the sync I have 3 wires with the same color of orange with red bands.

I didn't try what mod said, incidentally the wire that I did break was the one going to the -H pin, but I didn't think to remove the -V.

thanks for clarifying with the grounds, I assumed that's how it was considering they're... ground.

going by the wiggling thing, were the harnesses on these prone to breakage?

game plays blind too, I neglected to mention that.
 
I'm not super familiar with Pac's, but I thought they were negative composite sync.
If yours has two sync wires, they would go to the -H and _V like you described. But look down the line on the video input harness for a small jumper/loop connector to tie the two together. (not sure if Pac's have one)

The K7200 will not sync properly if you put the negative composite sync on the -V pin also. It is like the K7000, D9500, etc in that regard. If he was using a G07, then he'd need to connect both...
 
The K7200 will not sync properly if you put the negative composite sync on the -V pin also. It is like the K7000, D9500, etc in that regard. If he was using a G07, then he'd need to connect both...

ah, well that explains the duplicates. but why 3??? that's weird.

I just hope it's a monitor issue I can fix and it's not something board-related. there's a symptom with like the 6 MHz clock shorting that can cause the same thing.

thanks gents, I won't get around to it until probably monday though.
 
There should only be the one sync wire jumpered to the V and H pins for a normal Pac Harness. If it's jumpered to the ground pin, that would also cause a problem. For the K7200, don't connect the -V
 
Back
Top Bottom