Boards Sega Mega Drive II (Model 2) VA1 — PAL (Mega Drive II) OP1
OP1

C324G (LM324-type quad op-amp)

Audio op-amp SOP-14 Sega Mega Drive II (Model 2) VA1 — PAL · Mega Drive II
LM324-type quad operational amplifier in the audio circuit (two of these mix and amplify the FM, PSG and cartridge sound).
Find datasheet
IC7 OP2

Other components on Sega Mega Drive II (Model 2) VA1 — PAL

CART1 ENC1 IC1 IC4 IC5 IC6 IC7 OP1 OP2 OSC1 REG1 WRAM

About this component

Model 2 VA0/VA1 boards use a dual LM324 arrangement for audio. It's known for lower PSG volume and some hiss and distortion on the FM output; VA1 changed resistors R42–R45 from 4.7 kΩ to 7.5 kΩ and R81 from 6.8 kΩ to 4.7 kΩ to reduce the distortion. Many owners fit an audio improvement mod (e.g. a replacement amp board) rather than repair this circuit. Quiet, distorted or one-sided sound with a good picture points here, along with its capacitors. Sources: https://consolemods.org/wiki/Genesis:Motherboard_Differences , https://www.ti.com/lit/ds/symlink/lm324.pdf

Pinout & readings

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