720 Resetting/Graphics Issue

nerdygrrl

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machfelon just came and picked up my 720. When he arrived we had to tweak the optics board a bit to get the joystick to work properly. Since then the game has been resetting/having graphic issues when you try and coin up or use the CP.

It isn't consistent. We coined up the game and played for a bit before he left to test out the joystick and it worked fine. He just got it home an now can't get the game to load.

All the tests indicate the RAM/ROMs are fine.

I tested the PS when I bought the game in January and all the volts were fine. I only logged two hours of play on it since then, but am wondering if the PS could be going.

We're about five hours apart s I can't just run over and test the PS.

Any ideas my fellow KLOVER's
 
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machfelon just came and picked up my 720. When he arrived we had to tweak the optics board a bit to get the joystick to work properly. Since then the game has been resetting/having graphic issues when you try and coin up or use the CP.

It isn't consistent. We coined up the game and played for a bit before he left to test out the joystick and it worked fine. He just got it home an now can't get the game to load.

All the tests indicate the RAM/ROMs are fine.

I tested the PS when I bought the game in January and all the volts were fine. I only logged two hours of play on it since then, but am wondering if the PS could be going.

We're about five hours apart s I can't just run over and test the PS.

Any ideas my fellow KLOVER's

I have found many problems that were easily fixed with just the power supply, either buy adjustments or replacement. It very well could be the power supply and should always be checked. I have gone on service calls and found the power outlet was turned on by a light switch. If it is a switching supply it probably needs adjusting. If it is an original it probably needs rebuilding/replacement.

This is such a common problem I put it in my signature. I put the allways in there on purpose. In ham radios I have a cheap meter hooked up to my supply at all times so I can watch spikes, drops, and losses. I would hook a multi meter to the +5 line a watch for changes when you coin up or do whatever is trigger for your problem. If it is not the +5 volt line then check the +12.

If it is not a supply problem then I would look at inter-connectors/cables.
 
Ok now the game has constant errors. Wont load or if does immediately resets with garbage. And teh joystic does not work at all not and neither do some of the buttons.
 
DSCN4381.jpg

just colors on screen

DSCN4383.jpg

some kinda short going on in here
 
I can't tell if the optic board is a red herring. Machfelon just unplugged the CP and the game booted fine, plugged the the CP back in and graphics issues. Now the even the test mode is getting graphic errors. Could the CP be causing this?
 
I would check the power supply with the cp unplugged and then with cp plugged in. It sounds to me like something is being shorted to ground.
 
Now the game doesnt boot at all with the CP plugged in or unplugged. Screen is now a BSOD. "Blue Screen of Death" nothing no game sounds or anything. Just blue screen.
 
Always bad power issues with 720. When got mine, the connectors were burnt and I had multiple other power related issues. Replaced it all and got a new switcher and I was fine. After about 7-8 months, I started getting garbage occasionally on the screen as I started running more games. When I turned up the power supply, it all worked fine. I tested the +5v on my boards and they were running about 5.04...which is fine..however after a while, I decided to measure my power direct from the switcher and it was 5.3v! I was getting the same readings in my wiring harness, and finally figured out that the power loss is occurring at the connectors from the board and wiring harness (where there were burnt connectors before). I've seen 3 720 boards with burnt connectors, so this is obviously a common problem for whatever reason. I have new ones sitting in my shop right now, but haven't had a chance to replace them yet. I think my first suggestion would be to test your 5v on the boards and then test your switcher as well, if they're both a little over 5v then your issue is somewhere else. If your switcher is putting out 5v and you're like 4.75v on your board, you might turn it up to get 5v on your board, temporarily, to see if that fixes the issue. If it does, then you need to see where your voltage drop is. Like I said, I tested my wires and they were fine, but when I checked the voltage on the solder side of the board of my connectors, that's where I found my voltage drop.
 
The issue seems 90% likely to be the PS. Is there anyone in the NJ area that would be wiling to go and test the volts for machfelon and myself? I am located in MA and the 8 hour round trip for a five minute volt test seems a bit much and machfelon doesn't have a volt meter to do the test.

I could reward you with some parts or beer or something.
 
sounds to me like the 32mhz crystal in the center of the board is going or has gone.. when i reparied a 720 board i have, it had THAT VERY COLOR screen... same symptoms.. i really dont think it has anything to do with the PS.. its a switcher so i dont think thats bad....i mean you can get another switcher to see, but i dont think its that!
 
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sounds to me like the 32mhz crystal in the center of the board is going or has gone.. when i reparied a 720 board i have, it had THAT VERY COLOR screen... same symptoms.. i really dont think it has anything to do with the PS.. its a switcher so i dont think thats bad....i mean you can get another switcher to see, but i dont think its that!

What does the 32mhz crystal do and do you have any other symptoms for a failed crystal other than the screen color?

The reason why I think the switcher is going is because when we swapped the optics board the game started to glitch. We then reinstalled the previous optics board, but the game was still glitching about 5% of the time. It would make a little sound like a record skipping and we would get a broken graphic.

It seemed to be triggered by a power surge-i.e. when you coined up or when you tried to start the game. It seemed fine when we went and tightened all of the connectors, we went through the test run and reconfigured the joystick and everything was working fine. Turned it on-turned it off-coined it up. I have no real first hand knowledge of what is happening now only machfelon photos.
 
What does the 32mhz crystal do and do you have any other symptoms for a failed crystal other than the screen color?

The crystal is used by the clock generation circuit. If the crystal is bad then the clocks would not work and nothing on the main pcb board would function. I do not know enough about the 720 hardware to know what the visual symptoms of that would be, but it is one of the first places to check after measuring the power supply.
 
The crystal is used by the clock generation circuit. If the crystal is bad then the clocks would not work and nothing on the main pcb board would function. I do not know enough about the 720 hardware to know what the visual symptoms of that would be, but it is one of the first places to check after measuring the power supply.

Thanks!

Hopefully I can find someone down near machfelon to test his PS and we can go from there.
 
The crystal is used by the clock generation circuit. If the crystal is bad then the clocks would not work and nothing on the main pcb board would function. I do not know enough about the 720 hardware to know what the visual symptoms of that would be, but it is one of the first places to check after measuring the power supply.

You beat me to thr punch... Lol ... Exactly what he said.. Thats why i think it is that..
 
Thanks everyone. I think we have it narrowed down, but please feel free to keep the suggestions coming. I would like to get this thing fixed for machfelon ASAP. This is really helping me close in on the cause.

I apologize for all of he posting, but this is the worst possible scenario for seller/buyer. It sucks being so far away and not being able to go and work on/look at the machine.
 
My 720 has died at least twice resulting in (initially) constant resets and booting to garbage. The first time it was the +5v power supply, the second time it was the GND leg on the T-11 processor - it had corroded and fractured (I don't think it had ever been removed from the socket).

Also, as far as I'm aware the +5v comes from a switch mode power supply but the other voltages +/-15 I think) are supplied from the AR board behind the coin door and from experiments on my test rig it needs the +15v to the CPU and video board (at the least) in order to boot.

Entry level meters cost only a small amount so I'd get one of those if I didn't have one already and check the voltages on the test points on the board.

Good luck.

Karl.
 
Add one more to the "my crystal failed" list as well. That gave me garbage on my screen. I'd check PS first, connectors, then crystal. I think Bob Roberts sells them for $10-15. Don't know what's involved in installing one.
 
Add one more to the "my crystal failed" list as well. That gave me garbage on my screen. I'd check PS first, connectors, then crystal. I think Bob Roberts sells them for $10-15. Don't know what's involved in installing one.

pretty easy to install just unsolder 2 legs then install new one... Bob roberts doesnt sell them this guy does...

http://www.ataricade.com/index.htm

edit... if atraricade is even in business anymore... not sure....
 
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Where is this crystal? My game only boots to a garbage screen and all voltages are good, no burns or anything.
 
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