Samurai Shodown 5 Special/Perfect - Improperly decrypted V-Roms

[Neo-Alec]

Thanks for confirming. I bought four of the flash memory chips with the corrected rom on them from buyicnow this time around, so I have three left. I think I'll clean it up and give it one more try before giving up and ordering a new cart.

 

[Neo-Alec]

Sorry to hear that, the board should still be fine as long as the pads are still in place.

Here is my method

Once the old IC is removed, use some flux and desoldering braid to remove excess solder from the pads. Clean the area with ISO and apply a fresh application of flux to the pads, line the IC up and use light pressure with your finger to hold it in place. With a freshly tinned tip, tack two of the corners down rotate the board and tack the other two corners down. From this point you can apply another application of flux to pins; clean your tip and add fresh solder and then drag solder the pins.

After your first drag you might have excess solder in places, just clean your tip add more flux to the pins and drag solder from the point of excess without adding any solder to your tip. Inspect with a magnifying glass, or microscope, clean your tip and add more flux and repeat as needed.

The key is to take your time and use LOTS of flux, dont flood the board or anything but you should pretty much be adding more flux after everytime your iron touches the board, unless your done soldering.

I want to thank you again for the detailed instructions, and for documenting the V rom issue with this game so well, @Niko, because today I was finally successful thanks to all of this! Thank you again to everyone else who chimed in and helped/encouraged me along the way.

In hindsight, I did not give my wife your detailed instructions or give her enough information going into working on this, so it wasn't reasonable to hand this job off to her in the manner that I did. I ended up cleaning up the board one more time, and finishing this on my own. Having a good magnifier was key.

This was the best I was able to clean up the messed up contacts this time around before proceeding:

The finished job. (The yellow blotches are something that came with the chip from buyicnow.)

 

[Robbbert]

thanks @Nic034 .
You mention 16BC0 only, but on that other forum they posted that 4 changes were necessary. Let me quote them:

0x06bc0 was 0xab, should be 0x08
0x0ed41 was 0x08, should be 0x89
0x16bc0 was 0x6e, should be 0x82
0x1ed41 was 0xda, should be 0x8f

How many should I change? All 4, right?

For encrypted roms, change these 4.

00000: E0 -> 43
00001: 25 -> C9
18180: AC -> 2D
18181: 7E -> 2B

The decryption in MAME has a group of 8 xor values. If any were wrong then every 8th byte would be incorrectly decrypted. So, perhaps there's another layer of encryption that only affects 4 bytes? Doesn't make sense.