Terminator 2 U99 Issue

[Lastsix]

I have a Terminator 2 board that boots but shows a U99 error. The U99 was pulled out and put into a Mortal Kombat; where it ran ok. The game will try to boot after self-test into a black screen with no sound but after 40ish seconds arnold schwarzenegger's face pops up (the hi-score screen). I can see no visible damage; any ideas on what to check first?

 

[mecha]

the 40 pin AUTOERASE chip by the U99 Williams Custom Chip(tm) can cause all kinds of weird stuff on Y-unit games. the original socket is single wipe, I don't know if it's corrosion on the legs inside the socket or what but you get a lot of mileage out of replacing the socket. especially if you have blackout or reset issues. the T2 at my job is where I made this discovery lol

also for whatever reason T2 is one of those games that works better with the voltage a little bit low from all the games I've worked on. 4.95V to the chips seems to be the most reliable.

further reading: https://www.arcaderepair.net/mechas-essential-power-supply-guide-remastered/

 

[Lastsix]

Is it a dumb idea to remove the socket and solder the chip to the board? I noticed mortal kombat 1 does not have a socket on its u99.
Is there any way a bad ram trace can cause this error?

 

[mecha]

Is it a dumb idea to remove the socket and solder the chip to the board? I noticed mortal kombat 1 does not have a socket on its u99.
Is there any way a bad ram trace can cause this error?

Custom Chip and AUTOERASE chip are different components. I've never seen T2 with the Custom Chip socketed. they're kind of a nuisance to work with. I stole a socket from a High Impact Football board a couple years ago and soldered the chip in direct, it's apparently missing a connection somewhere cause it has graphic glitches now that won't clear. it will require some effort to desolder it back out again.

it's a thing where reseating the Custom Chip is the necessary first step if you get a U99 error. you already tested it in another game and it was good there. I fixed a T2 for a guy a few years ago thinking the Custom Chip was the fault, and it wound up being a BAD AUTOERASE chip. so I had to rob that from somewhere else in my collection.

 

[Lastsix]

The autoerase is U115 right? I have another board I can steal one from; do they have any kind of security?

 

[mecha]

The autoerase is U115 right? I have another board I can steal one from; do they have any kind of security?

it's a bunch of little PAL chips that are supposed to be for security in the vicinity of the CMOS.

and yes AUTOERASE is U115. manual calls it a PLD Autoerase Ctrl. those are the same between NARC Z-unit and Y-unit games, as are the Custom Chips.

 

[Lastsix]

Swapped the u115 from another board and no change. The socket on the board looks ok but may consider replacing with a new socket.

 

[Lastsix]

Cleaned the board, tested roms, and re-socketed the u115, game seems to be running... for now.
Midway games don't have any sound without the sub-boards right?

 

[mecha]

Cleaned the board, tested roms, and re-socketed the u115, game seems to be running... for now.
Midway games don't have any sound without the sub-boards right?

yes, you need the sound board connected. assuming you don't have the boards connected, on T2 the CPU board ribbon cable goes to the driver board first and from the driver board to the sound board. always align the red stripe on the ribbon cable to the pins labeled 1/2 on the boards.

[pictorial evidence I assume is correct attached, stolen from gsrogers]