Dig Dug, Doesn't get through the self test.. just reboots

[nuebien]

I bought a Dig Dug machine today.  When I turn the power on, it starts the self test,  gets to the part where it says RAM OK, then resets and just keeps doing it over and over.  Any ideas how to diagnose further?  TIA.

Jeff

Here is a video of what it does.

[Q*Bert_OP]

Checked the +5v? Missing/Bad ROMs?

[CheffoJeffo]

Agree -- check power first, then check ROM seating/joints.

Cheers

[D_Zoot]

Along with checking the voltage,  make sure you check the edge connector!  These Atari games have problems with overheating the game board edge connector causing low/erratic voltages to the game board.   Try cleaning the edge connector using a pencil eraser.

If the voltage is low on the game board, and the edge connector is ok look at the fuse holders on the power brick also unscrew the power brick from the bottom of the cab, flip it over and look for overheated connections at the rectifier bridge.  If all that is ok, there is a voltage adjustment on the ARII board, meter the +5 at the game board itself when adjusting this pot!

If the voltage ON the game board is ok then other things to look into:

Will the game go into test mode? (I doubt it from the looks of your video)

Pull the board and reseat all socketed chips

Big Blue!!

If all of that leads you nowhere, then you probably have a board fault and it will need repair.


Regards,
D

[fredster]

I had a centipede that did that. The way I fixed it was to take out the Z80 chip and clean it. 

If you have another board with a Z80 chip, the same Z80 chip, then you can swap and see if that helps.

But to me, the first thing I'd do is take out the CPU and reseat it.

[nuebien]

Thanks for the help guys.  I removed all 3 of the Z80 chips, one at a time, and cleaned the leads with a pencil eraser, and reinserted them.  I spent about 15 minutes on it.  I cleaned the edge connector leads.  I put the board back in and turned it on and it's still doing the same thing.  I then checked the +5 on the test pin on the board to ground on the board and got 5.0.  I read in another post that someone recommended uping the voltage a little.  Is that really a good idea?  I am going to pull the board again and reclean everything, spending more time on it, and try it again.  Thank you for your help. 

I gotta get this fixed soon.  I am allready bidding on 3 other machines.. hehe.

Jeff

Oh, and it doesn't do anything differant with the test switch turned on.  Thanx.

[kjoel0123]

I have a dig dug pcb for sale if interested asking $40 shipped. States working on it as I dont have an adapter to test it.

[nuebien]

Which one is it?  I believe there are 3 differant ones.  There is the namco which says namco on it, and there are 2 atari ones.  One atari has the 3 z80 chips side by side all at the end of the board and the other atari has them scattered all over the board.

BTW.. While reseating all the chips on the board I found 2 chips that have a "0771" on them that have pins that are broken.  Anyone know if this would cause the problem I am having?  Is this ram or rom?  One more.. Where would I get replacement chips?  Thank you.

[fredster]

Broken legs can't be good.

I suggest that you first download the manual for the machine.
http://arcarc.xmission.com/PDF%20Arcade%20Manuals%20and%20Schematics/?M=D

is just one site. Google for "dig dug manual" and see what you need. Download the schematics.

Next, you have to learn a little about the boards.  Learn a little generic board repair and all about the logic probe.  Mowerman has a good site on how to use a logic probe. (they are like $15 bucks at radio shack and other electronics places)

http://users.adelphia.net/~68hc11/ for the mowerman files, good reading!

Then look over this board repair guide (it's for pinball, but it is the same for any board)
http://www.marvin3m.com/begin/index.htm

If you want parts, here's da man : http://homearcade.org/BBBB/
Bob Roberts. He has all the chips. Even if it isn't listed, tell him what you want.

What I would do is look at the board first, as you have done, then identify chips that look bad first.  Take a look at the schematics and see if you can find that chip.  Dig dug has a very extensive repair manual that includes trouble shooting. You are setting off the watchdog circuit for some reason.

You can go and find old files on the RGVAC (rec.games.video.games.collecting) group. There's years of advice in those logs. You can also look up arcade repair logs on the net.  That will give you more clues to what to look for. You did the basics already.

Next you can just replace the chips that are what you would consider bad.  Or you can get a logic probe and hook that board up to a power supply with 5V.  (an old computer power supply has that). Then use the logic probe to check each leg.  Compare that readout to another chip like it. If it's different, then you may have a bad chip.

Buy the chips you need from Bob Roberts or a hundred other guys who sell them on the net.  Look for "arcade chips".

That's what I'd do.

Failing that, just get on the RGVAC and ask if somebody can fix it for you cheap!

[nuebien]

Wow.. That is alot to chew on.  I really appreciate the direction.  I'm heading to Bob Roberts right now.  It may take a couple weeks to get the time to finish this up but I will post when I fix it.  Thanks again.

[RayB]

Broken legs are never good and very well could be the cause of your problem. Can you solder something that small? Give it a try.

[nuebien]

Yeah.. That's what I was thinking.  Drill and extremly small hole in the side of the chip just enough to get some solder on it and solder a wire to it.  Worth a shot.

[fredster]

No, you get a very small "trace wire" and solder it between the leg and the board trace.

Don't screw with the chip itself.