This amp had blown outputs.
Upon splitting the two boards and focusing on "the master", after replacing 4011s and 2110s i installed the new 90N20 and disabled both 2110s in order to monitor the waveforms.
I get a very nice 100KHz square at the inputs of both 4011s and at their outputs. Current draw is 1.5A.
Upon enabling the 2110s blue led ON, but the amp draws around 14A and over-heats all output fets instantly. However, i am able to set DC offset and for a strange reason the amp produces output (without a load).
I have been back and forth the entire amp, even replaced U4 on the feedback.
I believe there is something wrong with the dead time of the step output.
Any ideas?
Upon splitting the two boards and focusing on "the master", after replacing 4011s and 2110s i installed the new 90N20 and disabled both 2110s in order to monitor the waveforms.
I get a very nice 100KHz square at the inputs of both 4011s and at their outputs. Current draw is 1.5A.
Upon enabling the 2110s blue led ON, but the amp draws around 14A and over-heats all output fets instantly. However, i am able to set DC offset and for a strange reason the amp produces output (without a load).
I have been back and forth the entire amp, even replaced U4 on the feedback.
I believe there is something wrong with the dead time of the step output.
Any ideas?
Attachments
The one in the photo looks burned.
I think the dead time is generally introduced between sections of the 4011 using a parallel resistor and diode but I don't see anything that looks like that on your amp.
I think the dead time is generally introduced between sections of the 4011 using a parallel resistor and diode but I don't see anything that looks like that on your amp.
You are right, one of the gate resistors was burned so i replaced all of them.
This amp has no dead time adjusted on the 4011, but i have seen it in a 7K2. Should i try it?
This amp has no dead time adjusted on the 4011, but i have seen it in a 7K2. Should i try it?
Are they using a parallel resistor and diode at the output of the driver IC to induce deadtime? If so, increasing the value of the parallel resistor (to increase charging time slightly) may work. Don't try it if there is no parallel gate resistor/diode pair.
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