720 joystick losing its spot?

Ghostkiller

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Just got a really clean 720 and played a few games before i took her home but after playing a few more after i got it home the joystick seems to lose its original position which can REALLY throw off your game. Any of you 720 guys know whats going on here or if this is a common issue? He said the joystick was rebuilt and it feels good and all directions work just seems like it loses calibration ot something. Any fix for this? I dont remember the original one i played back in the day ever having this issue.
 
It is a pretty common 720 problem. It could be the dual optical board on the controller going bad or not getting the correct voltage so it looks like it's going bad. It might also be the LETA chip on the pcb going bad.

I would order a new optical board. If it wasn't the problem then you just have a spare.
 
hmmm guess i need to crack her open and see whats going on. Just kind of wanted an idea about if this was a common issue with these or not.
 
I got it to come up in test mode now slow rotations it sees it all day long and centers at 12 o clock like it should but if you try and do a fast rotation some of the squares arent registering and it seems to be the same ones not random. Also theres a slight stiff spot in the rotation though i havent quite been able to pinpoint it to the square locations that arent registering. I did notice my discs are a tad bit warped but they arent hitting the optics although on parts they do come rather close. Any thoughts on what I need to get to fix this issue? Also it seems if you calibrate it and start a game it plays perfect but once you get into the later (faster spinning) levels its like the joystick is off by 20 degrees or so and its sooooo annoying yet you go right back into calibration mode and it picks up the center and re calibrates itself and you go back in the game and its just fine till you start getting into the faster parts of the game.
 
The disc with only two slots is the one that keeps the guy pointed in the right direction. Generally unless the discs are totally kinked or bent or rubbing a lot they should work to keep the guy pointed in the right direction.

The LETA chip on the pcb is finicky. The power connector to the pcb tend to brown and fry and restrict voltage. To get the +5v to the pcb and to get the game to boot folks turn the switcher up. My completely untested theory is that the higher voltage wrecks the LETA. My 720 came with browned power connector and a similar problem as yours. It was bad LETA that I had to replace. The replacement went bad after a month or two. I replaced the power connector, turned the switcher voltage down and replaced the LETA again. I have been skating or dieing now trouble free for a couple years.

If the power connector is browned- replace it and check your voltage.

Dave at RAM controls has the optical encoder boards and he has been offering some great KLOV discounts recently. I would order a new optical board from him just to aid your trouble shooting. Like I said, if it's not the problem then you got yourself a spare.
 
Just got around to looking at this thing and voltage going to the board was @4.8v I rolled it up to 5v and it doesnt lose spot now and just had a 120k game, although i know ive done better back in the day. thanks alot! Now just gotta tear it down and see where the rough spot is coming from and im home free!
 
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