I got this amp from someone so I could attempt to fix it as a way to practice and learn how to repair class d amps. I don’t know what happened to the amp, but half of the PS fets were shorted or exploded, all of the output fets were shorted, there was a short on the 2113S. I checked all the gate resistors they all checked out good, I checked the Zener diodes and they all seem fine. The amp will power up fine, rail voltage is present, high side 59.9V, low side -59.2V. +15vdc and -15vdc is present. However, when audio signal is introduced the amp immediately goes into protect. It does the same if the switch is moved from master to slave. There is .129mV of DC offset.
I don’t know if this amp should have significant dc voltage on pin 16 of the 494 when main power and ground is applied but remote is NOT applied. I’m wondering if this could be the issue because the amp sits at 3.226V with B+ and ground and no remote applied. When remote is applied in the absence of an audio signal, the voltage on pin 16 drops to 2.949V, then when audio signal is applied, voltage on pin 16 jumps to 7.918V and the speaker relay and protect led are triggered. Pin 15 has 4.949 when remote is applied.
I’ve rechecked all of the fets and there are no shorts present. I could find no obvious shorts in the inductor on the output. The amp doesn’t exhibit obvious signs of a short condition on my bench power supply, the supply doesn’t go to constant current mode.
I’m sure I’m missing something, if anyone has any ideas of what I should check, please let me know. Thanks in advance.
I don’t know if this amp should have significant dc voltage on pin 16 of the 494 when main power and ground is applied but remote is NOT applied. I’m wondering if this could be the issue because the amp sits at 3.226V with B+ and ground and no remote applied. When remote is applied in the absence of an audio signal, the voltage on pin 16 drops to 2.949V, then when audio signal is applied, voltage on pin 16 jumps to 7.918V and the speaker relay and protect led are triggered. Pin 15 has 4.949 when remote is applied.
I’ve rechecked all of the fets and there are no shorts present. I could find no obvious shorts in the inductor on the output. The amp doesn’t exhibit obvious signs of a short condition on my bench power supply, the supply doesn’t go to constant current mode.
I’m sure I’m missing something, if anyone has any ideas of what I should check, please let me know. Thanks in advance.
Post a good quality photo of the component side of the entire main board and the component side of any driver boards if no one can help.
Do you get any rail-rail oscillation when the amp is powered up and idling, no audio input?
Does it go into protect with no load on the speaker temrinals?
Does it go into protect with no load on the speaker temrinals?