I have a CX600.1 from 2016, and this tiny little amplifier is kicking my butt...
It originally had a short between the output mosfet and one of the rails. I forget which, its been a few years. Then suddenly this short went away.
Regardless, I replaced the IRS20957 and the two output transistors just in case it was that. The short never came back, but the amplifier will not start. It looks like its very similar to the UcD DIY amp designs and it is self-oscillating. Tangentially, this is why i never liked self-oscillating designs as they are nearly impossible to troubleshoot without it being able to kickstart
So as it stands currently, theres about 1.1V DC on the output terminals and the amplifier wont start. the Protection LED is stuck on as well. I am not sure where to go from here without a schematic.
the +/-15VDC is present on the LM311, and the 12V is present on the IRS20957. none of the surrounding diodes are shorted
It originally had a short between the output mosfet and one of the rails. I forget which, its been a few years. Then suddenly this short went away.
Regardless, I replaced the IRS20957 and the two output transistors just in case it was that. The short never came back, but the amplifier will not start. It looks like its very similar to the UcD DIY amp designs and it is self-oscillating. Tangentially, this is why i never liked self-oscillating designs as they are nearly impossible to troubleshoot without it being able to kickstart
So as it stands currently, theres about 1.1V DC on the output terminals and the amplifier wont start. the Protection LED is stuck on as well. I am not sure where to go from here without a schematic.
the +/-15VDC is present on the LM311, and the 12V is present on the IRS20957. none of the surrounding diodes are shorted
Hey Mike,
You should have 10.3Vdc on Pin 2 IC4.
If not check ZD10 for 6.8Vdc across it. (reference zener for IC5-LM393 CSD circuit)
If that doesn't pan out, check Vdc on Pin 11(VCC) on IC4 using -VCC as reference, same as ZD8's(13v zener) anode, next to Q17-BCP56.
You should have 10.3Vdc on Pin 2 IC4.
If not check ZD10 for 6.8Vdc across it. (reference zener for IC5-LM393 CSD circuit)
If that doesn't pan out, check Vdc on Pin 11(VCC) on IC4 using -VCC as reference, same as ZD8's(13v zener) anode, next to Q17-BCP56.
The CSD terminal on the IRS2092 and the IRS20957 are control terminals. They have a CCS (constant current source) that charges or discharges the CSD terminal. The capacitor on that terminal determines the timing. When the terminal is released by external controls, the voltage starts to increase and as it passes two thresholds (voltages), the IC begins to oscillate then audio muting is released.
The CSD terminal can also be driven internally when the on-board over-current protection is tripped.
When it's below the thresholds (which are a percentage of the VDD voltage), the IC is shut down.
Refer to the information on pages 4 and 5 on the attached application notes.
Are the output FETs in the circuit?
The CSD terminal can also be driven internally when the on-board over-current protection is tripped.
When it's below the thresholds (which are a percentage of the VDD voltage), the IC is shut down.
Refer to the information on pages 4 and 5 on the attached application notes.
Are the output FETs in the circuit?
PapaZBill will have to help with that. The IC, if sensing over-current, can drive the CSD pin low but my diagrams are different than what you have. All of the diagrams I have use the 4013.
As a side note, you need to use identical output FETs or FETs that are known drop-in replacements due to the on-board over-current protection.
As a side note, you need to use identical output FETs or FETs that are known drop-in replacements due to the on-board over-current protection.
I could put the originals back in, but it was doing the same thing with those. Those outputs never failed short and with a tester they behave like mosfets. So this failure is some sort of anomalous thing.
I remember reading a short on the board and then it spontaneously went away. My gut feeling is an MLCC somewhere shorted and then blew itself open. But i dont have any of those values.
I am not sure what sources the current to the zener reference, but yes. it is bouncing up and down in a rythmic pattern.
I'm just wasting time since there is a better source of information.
I found a diagram with a 6.8v zener feeding a 393.It's being fed by a 1.2M resistor. That input is being driven by pin 7 of the 393 through a 4.7uf cap and a 100 ohm resistor.
I found a diagram with a 6.8v zener feeding a 393.It's being fed by a 1.2M resistor. That input is being driven by pin 7 of the 393 through a 4.7uf cap and a 100 ohm resistor.
Replace ZD10-6.8Vdc.
@Perry Babin Can you post the diagram you refer to. It appears to be similar to the the circuit used in the CXA6001
@Perry Babin Can you post the diagram you refer to. It appears to be similar to the the circuit used in the CXA6001
It does not statically check bad in-circuit. Unless its leaky somehow?
Also, do you have a specific part #?