| Electronics > Repair |
| Class D Subwoofer Amplifier Repair |
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| Harry_22:
Great! The diagnosis can already be made. Lack of voltage to start the IRS2153 controller. The rectified high tension 325V passes through resistor R201 and forms a voltage drop 16V across ZD201 zener diode which powers the controller. In our case, only 7.5V is generated at the zener. The conclusion is that something is lowering the voltage. To clarify this please first disconnect equipment from the mains. Measure resistance between D210 anode and pin 4 of IC201. Next measure resistance between D210 cathode and pin 4 of IC201. |
| geoffagain:
Great annotation to the diagram, thank you for explaining. It's helpful to understand the circuit. We have on the board measured at the zener ZD210 D210 anode and pin 4 of IC201 - 0hm D210 cathode and pin 4 of IC201 - rises quickly to OL then drops and settles at 9.6Kohm |
| Harry_22:
The zener diode is most likely broken. |
| David_AVD:
I had a leaky Zener in a SMPS the other week. The leakage was enough to pull the rail below the Vmin. |
| geoffagain:
Thanks for this, I replaced the zener with another from a donor board - still could be broken, I need to test both of them still. Same voltage at R201 I pulled R201 and it reads correct resistance out of circuit. |
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