Access to the Main Unit is required.
The "Line Level" audio output on pin 5 of Rear panel connector ACC1 is very low, with the manual stating 300mV. Normal Line Level is regarded as about 700mV. Although my MiniDisc Recorder had a gain control for its Analogue I/P it still couldn't make 0 VU. Here, by adding two resistors we can increase the gain of the audio appearing on pin 5 of ACC1.
- Remove the bottom cover.
- Remove 6 screws holding down Main Unit.
- Remove screw on rear panel inbetween ALC & Send RCA sockets.
- Remove heatsinking clip holding transistor to chassis.
- Remove flat ribbon cable to J3 in far right corner.
- Carefully pry PBA loose and fold over - see at left.
(I actually had to remove RF Unit shield and loosen a shielded cable to allow the Main Unit PBA to fold out).
- Locate IC-503, a NJM2058 OPAMP in an SMT SOIC14 package.
- Remove W3 0603 SMT link.
- Fit an 10k 0603 SMT resistor in W3's place.
- Fit a 1/8w 5k6 through hole resistor from IC-503 pin 9 to ground.
We have effectively changed the OPAMP IC-503c from being a unity-gain follower into a non-inverting amplifier with a gain of approx 2.5.
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