Strikers 1945 III (1999) audio repair

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    • Strikers 1945 III (1999) audio repair

      A buddy of mine droped off a strikers 1945 III with an audio problem. The music was missing, all fx plays fine in game and test menu.

      I located the DAC YAC516-M (U39) The digital side seemed fine. It's nice to hear the audio through the logic probe. On the analog side I did not get any signal. This gave me an excuse to pull out the oscilloscope (I still need to learn how to use it). The scope read 2.5V on both the left and right channels.

      Moving onto the op-amp 4741 (U44) output 1 read 4V and output 2 12V. I took a jumper wire and bridged input 1 and 2 of the op-amp for a second and the FM came back. I ordered a replacement on eBay which will get here in about a month. In the meantime, I lifted the pins for input 3 and 4 as those are not being used. Output 3 gave me the same fault (12V) so I moved onto output 4. Plugged it in and plays like normal. I will give this back to my friend and will replace the op-amp when it come in.

      If I knew what I was doing this would have been a quick repair. Nope, it took me 3 nights of piecing other repair logs and videos together. That's the fun of it I guess :D
    • The good thing is if you come across the same issue on the same board you'll know where to look

      Sometimes faults are common on certain boards, for example total loss of sound on MVS and CPS1 is often a bad Z80. They used a lower rated (cheaper) Z80 instead of Z80A (even though they silkscreened the board for Z80A

      Good work on the fix :)