G07 pot kit, now horizontal scrolling.

Michaelthurston

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Hey guys, just did a pot kit on my pacman's G07, and now I get the picture having a high speed horizontal scrolling. Which is weird considering there's not horizontal hold pot. These are brand new pots from bob...why would this happen? Thanks guys. Any tips on adjusting new pots is welcome.
 
I believe on the G07 the horizontal hold is labeled as horizontal frequency.

Wiggling the pot creating differences could point to bad solder joints, faulty pot, or a broken trace. Pull the board and recheck the solder joints. Also, make sure you reconnected the sync wire(s) properly.
 
When the board was pulled did you verify the traces? Also, are you certain that the sync connection from the game board is connected the same as before? Did you check the sync jack for cold solder and the plug for damaged connections?
 
Okay, traces are good. Sync was backwards. When I fixed it, the image came up perfect! For about 2 minutes..now it's very slowly scrolling horizontally, and it'll stop, then go the other direction. Adjusting H freq, just makes it worse. Nothing will make it hold.
 
What do you mean by backwards? Was the 3 position connector plugged in upside down? Try moving it over one spot to the right, it will not be plugged in correctly but it will plug into place.


Also, when you did the cap kit did you do the sync mod?
 
Was the sync mod previously done? When you removed the cap from the 300 series position was it a can or a disk?

So there are two wires from the sync, one going to each of the negative polarity positions? In my experience, when I just can not get it to sync, it has often been a bad joint on the sync wires.
 
I pulled this from a previous G07 discussion. Has all of this been done?


Standard practice on a GO7 is to reflow the input headers, meter FR901 & 908, check FR401 for rotted legs. Also check R303, 306, 314, 317 and verify they are 390Ω because some had wrong value from the factory.
 
I couldn't see it because I was at work and Photobucket is blocked.

Can you get the pic to square up?

You have a triple image there as well. Like I said above, the IC may have been damaged in the past since it is in a bad location. If the cover has been pulled off and someone used a metal tool to adjust the pots they could have shorted to the IC frying it. I have seen this a few times on G07s. Do you have another game or a signal generator that you can connect to the monitor? If the problem remains you will have ruled out everything on the cabinet.
 
I've seen scrolling for 2 reasons, and there may be more reasons that it could occur.

1. sync not correct
2. b+ too low
 
make sure you put back in C501 after you did the sync mod....i forgot about it the other day and my h-freq wouldn't hold...scrolled all the time.
 
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