Persamaan Transistor D998 B778 Install | 2026 Release |

These transistors are complementary (NPN and PNP) power audio transistors commonly used in high-fidelity audio power amplifiers.

Langkah 3: Persiapan Heatsink (Pendingin)

Ini adalah kesalahan fatal:

• Pastikan isolasi sempurna. Badan logam transistor (kolektor) bertegangan penuh (Vcc/Vee). Jika menyentuh heatsink yang sama, akan terjadi korsleting.
• Gunakan Mika + O-ring + Baut nilon.
• Oleskan thermal paste tipis dan merata di punggung transistor.

3. Rekomendasi Ekonomis & Awet: TTC5200 / TTA1943 (Toshiba)

Ini versi "tiruan legal" dari Toshiba (bukan China fake). persamaan transistor d998 b778 install

• Spesifikasi sama persis dengan 2SC5200.
• Banyak ditemukan di amplifier rakitan lokal.

Sekilas tentang D998 dan B778

• 2SD998 (NPN) dan 2SB778 (PNP) adalah transistor power berpasangan.
• Spesifikasi utama:
  • Vceo (Tegangan Kolektor-Emitor): 120V
  • Ic (Arus Kolektor): 10A (Puncak hingga 12A)
  • Pc (Daya Disipasi): 80W
  • Frekuensi (ft): 20MHz
• Karakteristik: Gain (hFE) yang linear, suara hangat, dan cocok untuk amplifier tegangan simetris.

Langkah 2: Lepas Transistor Rusak

• Jangan langsung cabut. Ukur dulu dengan multimeter dioda.
• Ciri rusak: short (bunyi beep antara B-C atau C-E) atau open (tidak ada tegangan dioda 0.5-0.7V).
• Lepaskan dari heatsink dengan hati-hati. Bersihkan bekas thermal paste lama.

Steps:

Step 1: Amplifier Discharge

• Unplug the amplifier. Discharge the main filter capacitors (using a 10W resistor, never a screwdriver).

Step 2: Remove Old Transistors

• Desolder the faulty D998/B778. Remove screws securing them to the heatsink.

Step 3: Heatsink Preparation

• Clean the old thermal paste from the heatsink and the new transistor's metal back using isopropyl alcohol.

Step 4: Insulation Check

• If the amplifier's heatsink is grounded (common), use a mica washer + thermal paste OR a silicone insulator pad between the transistor tab and the heatsink. The collector is connected to the tab.
• Exception: Some TO-3P are fully insulated (check with multimeter). If so, no insulator needed.

Step 5: Mounting

• Apply a thin, even layer of thermal paste on the back of the transistor.
• Place the insulator (if used) then the transistor. Screw it down lightly but evenly (do not overtighten – torque ~0.5 Nm).

Step 6: Soldering

• Insert the leads into the PCB holes. Ensure the pinout matches the board’s silkscreen (B, C, E).
• Solder quickly (max 3 seconds per pin) to avoid heat damage. Use a heatsink clip on the lead if necessary.

Step 7: Final Check (Before Power ON)

• Diode mode test:
  • NPN (D998): Red probe on Base, Black on Emitter → read ~0.6V-1.2V (Darlington has two junctions).
  • Check no shorts between Collector and Emitter.
• Continuity: Ensure no short between transistor tab and heatsink (if insulated).