Sansui AU-7900 Adjustment and Parts List
6. ADJUSTMENT
6-1. Driver Circuit Board Adjustment
Notes:
- Master Volume: Minimum
- Room Temperature: 18°C~28°C
- Before this adjustment, turn VR01 and VR02 fully counterclockwise.
- For this adjustment, run the unit for more than 3 minutes after power is switched ON.
| STEP | EQUIPMENT | MEASURE OUTPUT | ADJUST | ADJUST FOR | CONDITION |
|---|---|---|---|---|---|
| L-CH Bias Current | DC Volt Meter R59, R61 of F-2596 Fig. 1 | VR01 | 18mV ±1mV | Fig. 1 | |
| R-CH Bias Current | DC Volt Meter R60, R62 of F-2596 Fig. 1 | VR02 | 18mV ±1mV | Fig. 1 |
* Instead of measuring bias current, set the voltage to 18mV as Fig. 1, since there are no quick acting fuses on the power amplifier.
Diagram: Figure 1 shows the location of VR01, VR02, R59, R60, R61, R62 on the F-2596 board, with connections for a Volt Meter to measure bias current.
6-2. Replacement of power Transistors
- Remove bottom plate.
- Remove screws, ①, ② installing on F-2596 as Fig. 1.
- Remove screws, ③, ④, ⑤, ⑥ installing on heat sink as Fig. 2 or Fig. 3.
- Remove driver & power supply circuit board ass'y (F-2596), then replace the transistors with new ones.
Diagrams:
- Fig. 1: Bottom View of F-2596 board showing component locations (VR01, VR02, R59, R60, R61, R62) and Volt Meter connections.
- Fig. 2: Rear View of AU-6900, AU-7900 showing screw locations (①, ②, ③, ④, ⑤, ⑥) for heat sink removal.
- Fig. 3: Rear View of AU-5900 showing screw locations (①, ②, ③, ④, ⑤, ⑥) for heat sink removal.
3. PARTS LOCATION AND PARTS LIST
3-1. F-2596 Power Amplifier Circuit Board
*Value and Stock No. of most Resistors and Capacitors are shown in Common Parts List attached.
Diagram: The diagram shows the conductor side of the F-2596 Power Amplifier Circuit Board, with components labeled A, B, and C. Various resistors (R), transistors (TR), capacitors (C), fuses (F), and potentiometers (VR) are indicated with their respective numbers and locations on the board.
Component Identification:
- Section A: Contains numerous resistors (e.g., R01-R74) and transistors (e.g., TR01-TR20).
- Section B: Features more resistors, transistors, and capacitors.
- Section C: Includes capacitors (e.g., C601-C612), resistors (e.g., R601-R612), and fuses (F601-F604) with their voltage and amperage ratings.
Fuses:
- F601, F602, F603, F604 are rated at 250V, 6A.
- CAUTION: FOR CONTINUED PROTECTION AGAINST FIRE HAZARD, REPLACE WITH SAME TYPE FUSES.
Part Numbers/Labels: F-2596, F-2598, F-2596EY are visible on the board and associated diagrams.
