| Parameter | Condition | 2SD998 (NPN) | 2SB778 (PNP) | Unit | | :--- | :--- | :--- | :--- | :--- | | Collector Cutoff Current | (V_CB=120V, I_E=0) | max 10 | max -10 | µA | | Emitter Cutoff Current | (V_EB=5V, I_C=0) | max 10 | max -10 | µA | | DC Current Gain (hFE) | (V_CE=4V, I_C=1A) | 50 to 160 | 50 to 160 | - | | Collector-Emitter Saturation Voltage | (I_C=7A, I_B=0.35A) | max 1.0 | max -1.0 | V | | Base-Emitter Voltage | (V_CE=4V, I_C=1A) | typ 1.0 | typ -1.0 | V | | Transition Frequency (fT) | (V_CE=10V, I_C=0.5A) | typ 15 | typ 15 | MHz | | Thermal Resistance | Junction to case | 1.56 | 1.56 | °C/W |
Mengganti D998/B778 tidak hanya soal membeli transistor yang sama mereknya. Ikuti langkah ini: Persamaan Transistor D998 B778
| Parameter | 2SD998 (NPN) | 2SB778 (PNP) | | :--- | :--- | :--- | | Collector-Base Voltage (Vcbo) | 180 V | 180 V | | Collector-Emitter Voltage (Vceo) | 160 V | 160 V | | Emitter-Base Voltage (Vebo) | 5 V | 5 V | | Collector Current (Ic) | 12 A (15 A peak) | 12 A (15 A peak) | | Power Dissipation (Pc) | 100 W | 100 W | | DC Current Gain (hFE) | 40 – 140 | 40 – 140 | | Transition Frequency (ft) | 25 MHz | 25 MHz | | Package | TO-3P (or TO-247) | TO-3P (or TO-247) | | Parameter | Condition | 2SD998 (NPN) |
These are Darlington or high-gain single transistors (check datasheet – most versions are single BJT, not Darlington). They require proper biasing and a heat sink. | Original | Type | Direct Substitute |
| Original | Type | Direct Substitute | Comments | | :--- | :--- | :--- | :--- | | 2SD998 | NPN | 2SD1559 | Higher voltage rating, pin compatible. | | | | 2SD2012 | Good modern replacement. | | | | TIP41C | Caution: Pinout is usually B-C-E (matches), but TIP41C is slightly less robust in gain linearity for Hi-Fi. | | 2SB778 | PNP | 2SB1106 | Complementary match to D1559. | | | | 2SB1382 | Good modern replacement. | | | | TIP42C | Caution: Pinout is usually B-C-E (matches). Popular but lower audio quality. |
Pro Tip for Repair: The pair 2SD1559 / 2SB1106 is often considered a superior modern replacement for the D998/B778 pair because they offer better power handling and reliability while maintaining the same pinout.