Okay... I F'ed up. I was installing Nvram on my Addams Family and managed to screw something up. After reinstalling the CPU board. The DMD dose not light up, so it is not going through the computer test.

Instead "the thing" keep popping up, coming out going back down over and over and that is all the machine does.

What the hell did I do?

I did not do much when installing the nvram
-I removed the old ram (which was soldered directly to the board)
-installed socket
-installed the new NV ram
-I replaced the 100uf 10v cap at c31
-reflowed solder at my connectors.
-I de solder the battery pack from the board.

That is it.

I have gone over every CM of the board with a 10x loop, front and back looking for trace brakes or solder blobs.... nothing.

I only kept the game on for about 15-20 second since I knew something is not right.

Help.

I replaced the cap because it was 20+ years old and most caps become less reliable after 15 years. ...and I had the board out, and I had the correct cap

If the CPU is booting there is no info on the DMD screen. At start up the top and the bottom LEDs come on solid, for a moment. Then the top LED goes out, bottom LED stay on solid, and the middle diagnostic LED stay rapidly flashing.

I put back my old RAM in the new socket and the behavior of the machine is the same.

I literally looked every CM for solder bridges.

I reseated the ribbon cables three times, that was my first guess.

No traces are busted, but I found two possible solder bridges to negative where the interconnect cable bridges between the CPU board and the Power driver board. After cleaning those up, no more "the thing" problem.

However, now I have NO dmd whatsoever and the game is resetting every minute or so.

Sound & light work normally, you can play... until the reset. But again NO DMD (and it is not the DMD, I checked with a spare I have, also I checked fuses on the DMD board and reseated the ribbon cable from the DMD board to the CPU board.)

Anyone?

Okay here is what happened. After I installed the socket for the NVRam. I made a mistake and I thought I would reflow solder at the connections and change out the cap at C31, while the board was out and convenient to do all at once. The cap install was no problem, however when I reflowed solder at the interconnect ribbon cable between the CPU board and the Powerdriver board, I caused a solder bridge to ground at one of the contacts.

This cause “the thing” to pop in and out continuously. And it blew a 5a fuse at F111 on the Power Driver board (this was causing the game to reset over and over)

The dead DMD was caused by the ribbon cable at J60 (top right thin ribbon cable) on the Dot Matrix card. I had accidentally reversed it a week prior (I had tested another DMD in the machine a week before and connected the ribbon cable wrong then, and did not fire up the machine before pulling the CPU board for the NVRAM install, so I never noticed the DMD was out before I even began the install.)

The installation of the NVRAM socket went flawlessly and looked like a pro job (I have installed many sockets); which was what was so confusing. But that flawless socket install was marred by several rookie mistakes: flipped ribbon cable to DMD, solder bridge at connector, not noticing the blown fuse afterwards, not doing the CPU board in stages.

Going ahead and doing a “quick reflow” of solder “while the board is out and convenient” is a mistake.

I should have:
-removed ram… installed socket…installed NVRAM and reinstalled board in machine and tested

-then reflowed solder at a connector reinstalled board in machine and tested

-then reflowed solder at next connector reinstalled board in machine and tested… and so on.

-replaced the cap reinstalled board in machine and tested.

Regard the anypin NVRAM from lockwhenlit.com works great, and was worth the effort. However if you are inexperience with chip removal and socket install I do suggest having an experienced tech doing it. If your game has its own socket that holds your ram, you will be okay installing it yourself.