Area 51 had watchdog resets, now won't power up

Tempo502

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I just bought my first arcade, Area 51 / Maximum Force duo machine. It worked great for about a week, then started throwing watchdog resets. I swapped the hard drive and decided it was a power supply problem. (Putting the hard drive on a separate power supply made it run much better. Also, tweaking the 5v supply up/down changed how often it reset.)

I started checking stuff with my multimeter, but after switching between VDC mode and VAC mode with the meter on the 5v rail, the board shut down. I haven't been able to get the system to power up in attract or test mode since then.

I assume I fried something, but I don't know what. The monitor works, the power supply is sending the right voltage, and the board power light is on. But the bus light and the disk light just stay off.

Any suggestions to try to troubleshoot this?

System specs:
Random JAMMA cabinet retrofitted for light guns
Main board is Atari Cojag 68k A053538 (dual board)
Modded with Area 51 / Maximum Force duo kit
Original board manual here: http://www.emuparadise.org/MAME/manuals/arcade/area51.pdf
 
What do you have the +5V set to? My experience with them is that they're VERY picky on voltages, and typically require around +5.2V on the +5V rail (and the overvoltage LED is usually on).

DogP
 
It was around 5.02 when I got it, and I dialed it as high as 5.1 but didn't want to burn anything out. How high can they go without breaking?

I just dialed it up to 5.17 and it loaded to a watchdog reset, which is progress. Any idea why the required voltage would keep creeping up?
 
Try 5.25v to see if itll boot.

Now if it boots touch/wiggle the jamma conector. did it reset? then the connector is an issue. check thr board edge for dirty contacts too.

I have also heard of hard drives causing watchdog on those boards.

also might not hurt to pull and reseat the cable that goes between the boardset and the hard drive on both ends.
 
I put the new hard drive on an independent power supply and the game ran for about 10 minutes with no problems at 5.17v. It's churning through self-diagnostics now. I don't have a problem with raising the voltage, but I'm still wondering why it ran at 5.02v a few weeks ago and needs >5.15v now.

I'd like to get rid of the secondary power supply but the new hard drive seems to make the internal power supply's 5v rail jumpy. Need to experiment with that a little bit...

Just getting it to run is a relief, so thanks a ton guys.

It's probably unrelated, but do you know any reason why the guns won't track the upper left and lower left corners of the screen?
 
I'm not sure why they need higher voltages, but it definitely seems common. The hard drive could definitely cause watchdog resets... it might not be a bad idea to switch to Compact Flash, which would probably lower the load on the power supply as well as ensuring that you have a good HD image.

I'm using something like: http://www.microcenter.com/single_product_results.phtml?product_id=0255159 with standard CF cards on a couple of my games, and I just burn the HD images to the card from the MAME dumps.

The gun problem could be a few things... the first thing I'd check is the monitor adjustment. Turn the brightness up a little bit and see if it gets any better. Also, make sure the +5V at the gun is good (are you seeing a common theme here? ;) ). Also, clean the monitor (and mirror, if the cabinet uses one) and gun lens.

DogP
 
The first thing I'd do if it were me would be to replace the power supply.

If the caps are going out you'll get all kinds of trash noise on the +5v rail which would make the board do all kinds of goofy things.

Next would be to try a new hard drive.

There's a WDOG jumper on that board. If it's open, close it to disable the watchdog reset and see what the board is doing.

RJ
 
channelmanic -- I looked high and low and couldn't find a watchdog jumper. I don't think this board rev has one.

The new hard drive pulls the 5v down by about .04v when it spins up, and the board watchdogs at 5.15v, so I've got it set to boot at 5.23v and then drop to 5.19v when the disk spins. Looks like that's a good sweet spot... No watchdogs in several hours of uptime. I may still replace the power supply and/or switch to compact flash.

Cleaning the guns/screen did not help, but adjusting the brightness DID make it better. Unfortunately it's a tradeoff between looks and tracking right now. Only one gun has an issue, what's that mean?
 
Usually that means the opto is going bad, or possibly a bad cable. Ramping up the +5V usually helps bad optos, but if your +5V is already ~5.2V, it's probably just going bad (unless the cable is frayed or something, causing more voltage drop than it should).

You could also try adjusting the monitor some more... turning the brightness/screen controls up usually washes out the picture, but adjusting up the contrast and individual color drive/cutoff should help by making the screen brighter without washing out the screen (though you may get some bleeding if you go too high).

You can look at the model number of the opto and order the part, or this is probably what you'd need to just replace the whole board: http://www.happ.com/amusement/optical/960066100smd.htm .

DogP
 
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