The pepper2 set recently got a supposedly newer set of sound ROMs. With them it fails the self test. I took a quick glance and I believe the recently added rev 2 sound ROMs are bad dumps. If compared to the old supposedly rev 1 ROMs they have the following changes.
5a: 1 byte change at 58d. Changes a LDA (a9) to a NOP (89). By changing this back the melody is restored but the game still fails the self test
6a: 2 bytes changed: 1f to 0f at 5ca, 2f to 0f at 22c
So 3 bytes changed total which cause the self test to fail and the first one also causes the melody to go missing.
Formerly (un)known as hanamichi on the mameworld.info message boards.