AES Ram issues after a repair

Summary:
I purchased a faulty AES from a local shop for a good price.It was having some ram errors as the background and sprites were all messed up. I added a socketed unibios, fix the red video line, and replaced the two main Sony ram chips based off an 8000 error I saw in the unibios hardware test. 9 of the games I have play great now.

I am having problems with two games.
1. Blues Journey failes the CRC check, but the same cart passes on my other AES. It also keeps rebooting and never gets past the first unibios screen. Also the bios settings keep getting set back to default. The cart slot contacts have been cleaned a couple times as well as the cart.

2. Nam 1975 will display a ram error if left in attract mode for a while.
Address : 0000006C
AC ADRS: FFFFFFFF
R?W: Read

check solder of 40pin dil bios.
looks like error from missed trace

I double checked the solder on the bios and it looked good. I will do a continuity check for the bios from the pins to where the traces should go. Thanks for the input

Black IcE said:

I double checked the solder on the bios and it looked good. I will do a continuity check for the bios from the pins to where the traces should go. Thanks for the input

Click to expand...

have you cheched prog board connector to 68k.sp1 ?

I spent some time with the AES schematics and a fluke meter tonight with checking connections to and from the bios. All connections were good between the bios and 68k, neo c1, cartridge slot, and both 43256 chips that are right next to the 68k. I also really cleaned the cartridge slot good again to make sure it wasn't the issue. One thing has changed after cleaning the cartridge slot though. Now Blues Journey passes the crc check but it still keeps resetting at the unibios start screen.

One other thing worth mentioning is I tried testing the board with smkdan's diagnostic bios and no error are reported.

I guess the next thing I will check are traces for the ram I replaced. I also noticed that the previous owner tried doing a cap kit and screwed up a couple traces I had to fix for the video output.

One other thing that I find odd is that if I leave the console powered off for a while, then Blues Journey boot and plays ok for the first power on. After the first run through the attract mode, it starts resetting again. I am wonder if there is some ram or another component that is either not grounded properly or that does not get reset when the attract mode starts over.

Black IcE said:

Summary:
I purchased a faulty AES from a local shop for a good price.It was having some ram errors as the background and sprites were all messed up. I added a socketed unibios, fix the red video line, and replaced the two main Sony ram chips based off an 8000 error I saw in the unibios hardware test. 9 of the games I have play great now.

I am having problems with two games.
1. Blues Journey failes the CRC check, but the same cart passes on my other AES. It also keeps rebooting and never gets past the first unibios screen. Also the bios settings keep getting set back to default. The cart slot contacts have been cleaned a couple times as well as the cart.

2. Nam 1975 will display a ram error if left in attract mode for a while.
Address : 0000006C
AC ADRS: FFFFFFFF
R?W: Read

Click to expand...

When you mention unibios settings getting set back to default - that will happen on an AES as there's no BRAM. Unless its saving to memory card? I would program up SMK Dan diagnostic BIOS and swap out the unibios to test the system. Maybe you have an intermittant RAM fault somewhere.