Repairing a Music Store Professional GO! SUB 18A

[h0m3w0rk]

Hello everyone,

I'm working on repairing a Music Store Professional GO! SUB 18A bass subwoofer, and I need some help troubleshooting an issue with the power amplifier board. The board uses an IR2153 driver and originally had two SLW20N50C MOSFETs. Unfortunately, these MOSFETs burned out. I replaced them with two TK20J60W MOSFETs; however, these also failed almost immediately.

Here are some details:

• SLW20N50C (original):
  • Rated for 500 V
  • Typical RDS(ON): 0.21 Ω
  • Continuous Drain Current: 20 A at 25°C (13 A at 100°C)
  • Pulsed Drain Current: 80 A
  • Avalanche Energy (Single-Pulse): 1110 mJ
  • Gate Threshold Voltage: approximately 2.0–4.0 V

• TK20J60W (replacement):
  • Typical RDS(ON): 0.13 Ω
  • Rated for 600 V
  • Continuous Drain Current: up to 20 A at 25°C
  • Pulsed Drain Current: 80 A
  • Avalanche Energy (Single-Pulse): 200 mJ
  • Gate Threshold Voltage: approximately 2.7–3.7 V

I've checked the board after removing the burned MOSFETs, and there's no short circuit present on the PCB.

My questions:

• Has anyone used the TK20J60W in similar mains-powered amplifier designs?
• Could the differences in dynamic behavior (e.g., switching transients, avalanche robustness, gate charge characteristics) between the TK20J60W and the original SLW20N50C be causing the TK20J60W to fail under the conditions present on this board?
• Could issues with the IR2153's gate drive—such as insufficient dead time or an improperly tuned snubber network—be exacerbating the problem with the TK20J60W?

Any insights, suggestions, or similar experiences would be greatly appreciated!

Thanks in advance for your help

[h0m3w0rk]

I've ordered the following SMD components to change them all based on the board markings, and I'd appreciate confirmation that these are the correct parts for the IR2153 circuit:

• WH – A surface-mount Zener diode. According to SMD marking databases, “WH” typically corresponds to a BZT52C12 series diode (≈12 V Zener) used for clamping the IR2153 VCC.
• 2L – A transistor marked “2L,” which is generally identified as the MMBT5401. This device is rated for around 150 V, which fits the higher voltage requirements on this board.
• 24 – A transistor with the “24” marking. This is commonly associated with the DTC114EU3 series digital transistor, which matches the typical 50 V rating seen on other similar parts.
• HF – A high-frequency transistor. The marking “HF” usually refers to a C1815 in a SOT‑23 package. Since the C1815 is not available, I've ordered an alternative (e.g., the MMBT3904 in SOT‑23) that should meet the frequency and switching requirements.
• T4 – A fast-switching diode, typically from the 1N4148 family in an SOT‑23 package, marked as “T4.”