Konami Aliens Sound Repair

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    • Konami Aliens Sound Repair

      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 :D :D :D

      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)
    • Ah by the way, I've checked the main program code while checking the sound mask rom, this PCB was not identified by the online romident. It might not be dumped by mame or the online romident site was not up to date. The code on the stickers of the program mask roms are "875 H01" and "875 H02"...
    • ekorz wrote:

      Nice write up! I'm working on some audio issues on a couple boards... you give me hope!
      Well, there is no "one-size-fits-all" solution to fix audio issues on Konami boards. May be the culprit is just a couple of capacitors may be the culprit is buried deeper. There is no obvious way of testing these components but I identified the failing 74LS74 flip-flop IC when I was reading the schematics and ruled out everything touching the Z80.

      Just be patient. My advice is, no matter how confident you think if the problem is related with the capacitors or not, just change all of them ("All" I mean the electrolytic and tantalum ones around the sound section) by principle. At the least you'll have smoother sound when you later find the real trouble maker ;)

      Generally, the usual suspects are the capacitors, sometimes the tantalums, YM3012, Sound SRAM, the Mask ROM having the Z80 sound code.

      Good luck...
    • Pratically you replaced everything :) Anyway, good job, the most important thing is that you managed to fix the board.
      Next time, to save you precious time, you can use an audio probe (a portable amplifier in few words) like this :



      In this way you can exactly determine if sound fault concerns the analog or digital circuit by "listening" various points on PCB (for example the output of the DAC which comes always before the analog pre-amplfication circuit).It's a very simple but effective piece of equipment, I higlhy recommed to build one.
    • yavuzg wrote:

      Ah by the way, I've checked the main program code while checking the sound mask rom, this PCB was not identified by the online romident. It might not be dumped by mame or the online romident site was not up to date. The code on the stickers of the program mask roms are "875 H01" and "875 H02"...
      Please share the dump of the program code and a picture of the labels and I will get them into MAME with credit to you!
      The future of ST-V rests upon our work and your work
    • rtw wrote:

      yavuzg wrote:

      Ah by the way, I've checked the main program code while checking the sound mask rom, this PCB was not identified by the online romident. It might not be dumped by mame or the online romident site was not up to date. The code on the stickers of the program mask roms are "875 H01" and "875 H02"...
      Please share the dump of the program code and a picture of the labels and I will get them into MAME with credit to you!

      Here are the pictures of this board set.








      And these are the close-up pics of the related mask roms...



      The sound ROM however shows up on MAME (Romident says its is from "aliensu" board set)





      And the serial number...

    • yavuzg wrote:

      I've dumped the main roms and here is the link:

      yavuzg.com/images/Repairs/konami-aliens-2/aliens_us_x.rar

      I did not dumped the other mask roms for the time being since they are soldered to the rom board. It would be a waste of time to dump all these soldered roms if this rom set turns out to be already existing in MAME.
      Thanks.No need to dump the MASK ROM since they store GFX and sound data that never changes in all different revisions.
    • caius wrote:

      yavuzg wrote:

      I've dumped the main roms and here is the link:

      yavuzg.com/images/Repairs/konami-aliens-2/aliens_us_x.rar

      I did not dumped the other mask roms for the time being since they are soldered to the rom board. It would be a waste of time to dump all these soldered roms if this rom set turns out to be already existing in MAME.
      Thanks.No need to dump the MASK ROM since they store GFX and sound data that never changes in all different revisions.
      That's good news!
    • Now I noticed your Alien uses a second board.Instead of using 4Mbit/2Mbit MASK ROMs, GFX data have been splitted into smaller devices (probably 27256 or 27512) located on this board.Maybe we should dump them as well although I'm sure data is the same.
    • caius wrote:

      Now I noticed your Alien uses a second board.Instead of using 4Mbit/2Mbit MASK ROMs, GFX data have been splitted into smaller devices (probably 27256 or 27512) located on this board.Maybe we should dump them as well although I'm sure data is the same.
      Thats why I said "good news" before :)

      I'm totally comfortable in desoldering stuff since I have the equipment and experience. BUT... desoldering 28 mask roms... man I must be highly motivated :D :D :D
    • caius wrote:

      Now I noticed your Alien uses a second board.Instead of using 4Mbit/2Mbit MASK ROMs, GFX data have been splitted into smaller devices (probably 27256 or 27512) located on this board.Maybe we should dump them as well although I'm sure data is the same.
      In the test menu there is the "character rom check" section. There you can see the checksums of the mask roms. The screen however only lists the mask rom locations on the main PCB not the individual mask roms on the rom board. So I guess you are right, the smaller mask roms are indeed make up the larger, more popular mask roms.

      At least I can take snapshot of that screen to see if the check-sums are indeed same as the well known mask rom check-sums...
    • caius wrote:

      Pratically you replaced everything :) Anyway, good job, the most important thing is that you managed to fix the board.
      Next time, to save you precious time, you can use an audio probe (a portable amplifier in few words) like this

      In this way you can exactly determine if sound fault concerns the analog or digital circuit by "listening" various points on PCB (for example the output of the DAC which comes always before the analog pre-amplfication circuit).It's a very simple but effective piece of equipment, I higlhy recommed to build one.
      very nice. I'd love to build one of these (...and then learn how to use it). Any more details you can share?
      multis: cps* ttx2 gnet f3 mvs sega st-v/16b/24/c2/naomi(netboot) sys2x6 m72
      cabs: sega blast city x2 | taito vewlix c + egret ii
      links: klov/vaps games list | custom fight sticks
      projects: some conversions, some repairs