Aliens Vs. Predator Repair Log

dbstallman

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I picked up a dead Aliens Vs. Predator last week expecting a quick and easy fix to add this excellent CPS-2 game to my collection.

Unfortunately, when I opened it up, I was greeted with this :
imag0382e.jpg


Here is a closeup of the damage :
imag0383e.jpg


This battery didn't simply commit suicide, it blew it's brains out with a shotgun! My heart sank. I could easily transplant the ROMs to another board and be done with it, but instead I decided to take up the challenge and attempt to bring this one back from the dead.

I removed the battery and started to clean off the largest chunks of oxidation and battery residue. I was hopeful that at least some of the damage would be just superficial and I could quickly get the board back in business.

After I had the bulk cleaned away, I burned Raz's Suicide Tester ROM and put it on the board just check and see how bad the damage was. It booted up and passed all the tests with only a slight amount of graphical glitches in the text. This was very encouraging.

I started trying to get all the battery residue off the board. The electrolytic cap in front of the battery and a small transistor that is between it and the battery popped off with the residue, but both of those components are part of the suicide circuit and not neccessary for the Phoneix code. I was able to successfully clean completely around the two 74LS245's, but I noticed the one closest to the battery didn't appear to have any connection to the board now. With only a small amount of further cleaning, it popped off the board. I tried to get the residue out from between the legs of the other 74LS245, but it soon came off the board as well.

All components within the toxic spill were now off the board and I was able to remove all the battery residue and oxidation. The board was now clean and I needed to start working to get it back into operation (sorry, I neglected to take a picture at this stage). I retested the board with Raz's ROM and got a blue screen but could hear the music playing. I went ahead and replaced the game ROMs with new Phoneix code ROMs and gave it another test. The screen was still blue, but I could hear the attract mode running and it responed to coins and played blind (well, blue).

I was able to find two 74LS245 SMD chips on a CPS-2 "A" board with bad cartridge connectors. I replaced the one that was farthest from the battery first since it still had the majority of it's solder pads in place with 15 of the 20 pin connections still functional. The last 5 connections I was able to jumper with short piecees of uncoated wrapping wire.

The other 245 was the tricky one. With no solder pads left for it, I needed to determine where the traces were supposed to go. I pulled another of my CPS-2 "B" boards and started following the traces. The pins on the side closest to the battery travelled under the chip and through vias to the bottom of the board. From there they went almost to the program ROMs and then through vias again back to the top. That looked like the best place to get my signal from. The pins on the opposite side of the chip just connected directly to the cartridge connector right below it.

I wired the chip up:
imag0388w.jpg


and then gave it a test:
imag0397o.jpg


Success!

This is my first repair log (although not my first repair). I want to give something back to the community since I have learned so much from the repair logs of others (ifkz, womble, channelmaniac, etc.). I hope this helps someone or at the very least is an interesting read.

Thanks,
Brian.
 
Top work - have never seen a battery quite as bad as that!!

Great write up too!!
 
Very nice! Always great to see a board brought back to life. :D

Oh, and thanks for the pr0pz on the repair logs! I'm glad you found them helpful.

RJ
 
I think the words "do not recharge" on the battery had something to do with the extent of the damage.

Not on CPS2. That's the normal battery found on 'em and they DO sometimes leak horribly. If you're looking at a CPS2 cart in a pile of boards, tip it back & forth to see if it sounds like it has a bunch of loose crap inside. If it does, it's almost always battery crap like the pic above.
 
Nice work but easy repair as your lucky the traces and or LEGS on the custom chip were not destroyed. Now thats when things get annoying.

Look at one of my AVP

TMP2.jpg
 
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I think the words "do not recharge" on the battery had something to do with the extent of the damage.

Yeah, like Raymond said there is no recharge circuit in CPS2 it dies regardless of how much you play but many seem to believe if you play it more it will "recharge" the battery. Same with CPS3. Not the case at all.

Most batteries i've seen leak run all over the board like in mainman's photo. I got one the other day that was a dead Vamp Hunter. US Blue which isn't very common. The battery leaked onto two of the main processors as it traveled across the board and completely ate all of the legs off of them. I used a donor board to make it a working board again.

Thing that pisses me off though is that it was listed as dead but maybe an eay fix on ebay but all of the screws were missing and the battery was gone. They knew damn well it wasn't an "easy fix".... Not much I could do since it was listed as dead...
 
Thing that pisses me off though is that it was listed as dead but maybe an eay fix on ebay but all of the screws were missing and the battery was gone. They knew damn well it wasn't an "easy fix".... Not much I could do since it was listed as dead...

I completly agree with you. I haven't bought a working CPS-2 board in over 5 years, I would rather get them cheaply and revive them.

I always hate receiving the board and finding that the security stickers have already been removed, usually an indication of a failed phoenix attempt.

This AVP board still had security stickers, the aluminum pin still intact and didn't rattle when I took it from the box and shook it (like RJ says, that is a good indicator of how much work is ahead). Unfortunatly, things weren't as easy as I hoped.

Still only took about 3 hours, though, so well worth it.

Brian.
 
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