Format: Integrated DC amplifier
Model: AU-D907F Extra
Released: 1981
Dimensions: W460 H160 D444 mm
Weight: 17.7kg
There are scratches and stains from use, so please refrain from bidding if this bothers you.
*** Maintenance, cleaning, operation check, and burn-in (including listening to records and CDs) have
been performed. All inputs and outputs and all switches have been confirmed to be working.
All PL lights illuminate.
*Main maintenance details
1. Main amplifier drive board: Degraded capacitors that affect sound quality were replaced to stabilize the circuit and improve sound quality. Key capacitors were replaced with audio-grade capacitors (Nichicon, FW). Image ⑨
2. Main amplifier drive board: The center 0V adjustment potentiometer, which is expected to deteriorate over time, was replaced and adjusted to stabilize the circuit. (Image 9)
3. Main amplifier drive board: The bias adjustment volume, which is expected to deteriorate over time, was replaced and adjusted to stabilize the circuit. Image ⑨
4. Input selector switch: Disassembled to improve poor contact, contacts adjusted, and cleaned with an electronic component cleaner. (Image 10)
5. Speaker relay: Disassembled and contacts adjusted to improve contact resistance. (Image 10)
6. RCA input terminals, SP output terminals: Disassembled, contact adjustment, and cleaning to improve contact resistance. Image 7
7. Inspect all circuit board and other component mounting points: Correct any soldering hazards, improve them by adding solder, etc.
8. MC transformer selector switch: Adjust the contacts and clean with an electronic component cleaning agent.
9. Clean any internal dirt with an electronic component cleaning agent or similar.
10. Front panel: Clean all knobs, etc. (Images ①②)
11. Repair scratches and stains on the exterior and wood parts using touch-up pens, etc. (Image 6)
12. After maintenance, shock tests and other tests were conducted to confirm that there were no abnormalities. (This test involves lightly tapping the entire unit while monitoring it with an oscilloscope and checking for noise, etc.)