I've got this PCB from ebay cheap as non-working. I used to own an Aliens PCB but sold with rest of my Konami PCB collection (Sunset, TMNT etc) to support other projects couple of years ago. That said, I've been trying to put back together my Konami PCB collection again.
Apart from re-collecting Konami PCBs, this PCB attracted my attention because of the fact that it was a very early US version that has two PCBs connected together. Most of the time you see single PCB Konami boards and notice some empty holes for possibly inter-board connectors on the edge of the PCBs this time there really were connectors soldered and a seperate ROM board was attached...
I just wanted to share my experiences with this board so that it may help anyone who has similar issues with their similar Konami board may benefit from... Sorry no photos this time
Anyway, the board turned out to be non-working as expected. After cleaning it up I carefully examined the custom Konami chips and there you go found bunch of lifted pins on 0519160. Re-soldered and the board booted. Hurray!
The game now plays fine but there were no sound (as generally expected from these Konami boards). However this PCB didn't have the famous weird Konami custom with full of surface mount capacitors.
Anyway, I started from changing the electrolytic capacitors since some of them were already swollen and some had bad legs. Nothing changed. Then I changed the 4.7uF/16V tantalum capacitors around sound section (That fixed my TMNT sound problem once). Still no change. I de-soldered the 5K volume pot since these sometimes go bad. As expected it was only adjusting till 1-2 K. After that it just disconnects. This was infact not the real cause of a sound problem since it was partially working but I just wanted to fix it and I like to keep the authenticity of the PCBs, I just opened it up (removed the aluminum cylindirical case) and cleaned it with rubbing alcohol and tightened the brush which contacts the carbon. That fixed the original volume pot problem.
However there were still no sound. Nothing. Not even a hiss or bump...
Then I changed the sound amp. No sound still...
Then I changed the YM3012 and socketted. Sound started... But it was weird. Music was delayed. Effects were sometimes delayed. Left it running for an hour. Then Re-booted. Again no sound! Few re-boots later I randomly heard "Aliens A-a-a-aliens" sounds and then complete silence...
I decided to go further down the line. Now I'm starting to moving from the analog world to the digital one since the last sound I heard from the PCB was a stuttered "Aliens" word, it was definitely not an analog issue anymore . Changed the YM2151 and socketted. No sound still...
Observed the pins of the big 007232 Konami custom chip, all the address and data lines coming from the mask ROMs (yes this PCB has 4 smaller mask ROMs for sound samples on the ROM board) were stuck low. Changed the IC (lucky I have two Konami Main Event PCBs in my part bin ) but still the same, no sound at all...
I was getting angry since I half-fixed the PCB but it was failing again infront of my eyes...
Anyway, I observed the mask rom legs which has the audio z80 code, I noticed Address lines 11 and 12 was stuck low. I thought, hey I got you!... But after reading it and checking it with romident revealed that the Mask ROM was indeed OK.
Then I thought the stuck address lines might be Z80 related. Changed and socketted the Z80. Gues what? Still no change
Then I desoldered and socketted the sound SRAM (6116) at location G5 to check it on my eprom programmer. The SRAM checked OK.
Now I ran out of options. Trying weird things. One funny thing I tried was running the PCB without the mask rom containing the sound program for z80. Gues what? There were weird random metallic sounds but still, indication of the rest of the sound section at least the analog part is OK.
Anyway, lastly I opened up the schematics (got from jammarcade.com - excellent site by the way for such resources). Examined the Z80 area. Noticed there was a flip-flop connected to Z80 seems to be having a key role in interrupt management. It was the 74LS74 at location F9. When I saw the Fujitsu logo on it I thought f***!
I desoldered it and tested on my eprom programmer. Turned out to be the flip-flops were gone bad.
Replaced it and fired up the board. FINALLY!!! Got all the sounds and music back
That tiny f***n logic IC from Fujıtsu made me socketted almost all of the sound section this PCB. Good news is that I now have very handy "test platform" for testing Yamaha chips and Z80s. (Turned out a YM3012 in my parts drawer was also bad - produced distorted sound effects)
Apart from re-collecting Konami PCBs, this PCB attracted my attention because of the fact that it was a very early US version that has two PCBs connected together. Most of the time you see single PCB Konami boards and notice some empty holes for possibly inter-board connectors on the edge of the PCBs this time there really were connectors soldered and a seperate ROM board was attached...
I just wanted to share my experiences with this board so that it may help anyone who has similar issues with their similar Konami board may benefit from... Sorry no photos this time
Anyway, the board turned out to be non-working as expected. After cleaning it up I carefully examined the custom Konami chips and there you go found bunch of lifted pins on 0519160. Re-soldered and the board booted. Hurray!
The game now plays fine but there were no sound (as generally expected from these Konami boards). However this PCB didn't have the famous weird Konami custom with full of surface mount capacitors.
Anyway, I started from changing the electrolytic capacitors since some of them were already swollen and some had bad legs. Nothing changed. Then I changed the 4.7uF/16V tantalum capacitors around sound section (That fixed my TMNT sound problem once). Still no change. I de-soldered the 5K volume pot since these sometimes go bad. As expected it was only adjusting till 1-2 K. After that it just disconnects. This was infact not the real cause of a sound problem since it was partially working but I just wanted to fix it and I like to keep the authenticity of the PCBs, I just opened it up (removed the aluminum cylindirical case) and cleaned it with rubbing alcohol and tightened the brush which contacts the carbon. That fixed the original volume pot problem.
However there were still no sound. Nothing. Not even a hiss or bump...
Then I changed the sound amp. No sound still...
Then I changed the YM3012 and socketted. Sound started... But it was weird. Music was delayed. Effects were sometimes delayed. Left it running for an hour. Then Re-booted. Again no sound! Few re-boots later I randomly heard "Aliens A-a-a-aliens" sounds and then complete silence...
I decided to go further down the line. Now I'm starting to moving from the analog world to the digital one since the last sound I heard from the PCB was a stuttered "Aliens" word, it was definitely not an analog issue anymore . Changed the YM2151 and socketted. No sound still...
Observed the pins of the big 007232 Konami custom chip, all the address and data lines coming from the mask ROMs (yes this PCB has 4 smaller mask ROMs for sound samples on the ROM board) were stuck low. Changed the IC (lucky I have two Konami Main Event PCBs in my part bin ) but still the same, no sound at all...
I was getting angry since I half-fixed the PCB but it was failing again infront of my eyes...
Anyway, I observed the mask rom legs which has the audio z80 code, I noticed Address lines 11 and 12 was stuck low. I thought, hey I got you!... But after reading it and checking it with romident revealed that the Mask ROM was indeed OK.
Then I thought the stuck address lines might be Z80 related. Changed and socketted the Z80. Gues what? Still no change
Then I desoldered and socketted the sound SRAM (6116) at location G5 to check it on my eprom programmer. The SRAM checked OK.
Now I ran out of options. Trying weird things. One funny thing I tried was running the PCB without the mask rom containing the sound program for z80. Gues what? There were weird random metallic sounds but still, indication of the rest of the sound section at least the analog part is OK.
Anyway, lastly I opened up the schematics (got from jammarcade.com - excellent site by the way for such resources). Examined the Z80 area. Noticed there was a flip-flop connected to Z80 seems to be having a key role in interrupt management. It was the 74LS74 at location F9. When I saw the Fujitsu logo on it I thought f***!
I desoldered it and tested on my eprom programmer. Turned out to be the flip-flops were gone bad.
Replaced it and fired up the board. FINALLY!!! Got all the sounds and music back
That tiny f***n logic IC from Fujıtsu made me socketted almost all of the sound section this PCB. Good news is that I now have very handy "test platform" for testing Yamaha chips and Z80s. (Turned out a YM3012 in my parts drawer was also bad - produced distorted sound effects)