Zaccaria Vanguard Maintenance 2023
26/07/2023 - Vanguard game PCB PA20200314 repair
Testing prior to the 2023 show had identified that there were missing elements from
the music track. There are two sample playback channels on this game, and I suspected one
of them wasn't working properly. Starting with ICs 51 & 52 (2716) found D0 to D3 active
on both suggesting digital sound data on both channels. Moving forward found:
- IC 55 (LS161) pin 15 - active - hi notes
- IC 56 (LS161) pin 15 - active - hi notes
- IC 57 (LS161) pin 15 - active - base beat
- IC 58 (LS161) pin 15 - active - base beat
- IC 48 (74393) pin 1 - active - hi notes
- IC 48 (74393) pin 13 - active
- IC 47 (14066BP) pin 2 - active - hi notes
- IC 54 (14066BP) pin 8 - active
- IC 54 (14066BP) pin 9 - floating
IC 54 pin 6 control input was toggling but pin 9 was always floating and I suspected IC 54
was bad. A piggyback brought all the music elements back and replacing IC54 (14066BP)
fixed the game.
prswan@gmail.com
