Well, I got one of these things in to get looked at and I actually got lost. I dont understand the IR2092 very well, and the datasheet really isnt helping me.
It had a missing -15V rail to the pre-amp, and had a bad op-amp in the pre-amp stage. So i replaced the blown inductor to the 7915, and replaced the bad op-amp.
the preamp works, while before it was driving pure DC into the IR2092 circuit. Thats all good.
But as you can expect, the IR2092 isnt running. I checked rail voltages, they are right at 70v and good. Checked the VCC supply going into the IR2092, and its also good. I have +/-5V on the input side of the 2092 as well. the output transistors were good, but i decided to swap them out anyway.
But it just wont run. I replaced the IR2092 with a new one, and it still wont run. decided to check all the capacitors in that circuit and seemed to be ok.
Thats when I decided to check the CSD capacitor with a scope, and thats when I noticed it was pulsing as if its tripping into shutdown and attempting to restart. it was just pulsing every half a second. it would drive high (5v) and fall, then drive back high again and fall.
Probing the gate signal on the output devices, it picks up a pulse/spike each time the CSD recycles. But it never goes into oscillation. I assume overcurrent? I checked output circuitry, no shorted inductor or capacitors, in fact I cant seem to find a short anywhere.
Anyone experienced in troubleshooting the IR2092 based amplifiers?
It had a missing -15V rail to the pre-amp, and had a bad op-amp in the pre-amp stage. So i replaced the blown inductor to the 7915, and replaced the bad op-amp.
the preamp works, while before it was driving pure DC into the IR2092 circuit. Thats all good.
But as you can expect, the IR2092 isnt running. I checked rail voltages, they are right at 70v and good. Checked the VCC supply going into the IR2092, and its also good. I have +/-5V on the input side of the 2092 as well. the output transistors were good, but i decided to swap them out anyway.
But it just wont run. I replaced the IR2092 with a new one, and it still wont run. decided to check all the capacitors in that circuit and seemed to be ok.
Thats when I decided to check the CSD capacitor with a scope, and thats when I noticed it was pulsing as if its tripping into shutdown and attempting to restart. it was just pulsing every half a second. it would drive high (5v) and fall, then drive back high again and fall.
Probing the gate signal on the output devices, it picks up a pulse/spike each time the CSD recycles. But it never goes into oscillation. I assume overcurrent? I checked output circuitry, no shorted inductor or capacitors, in fact I cant seem to find a short anywhere.
Anyone experienced in troubleshooting the IR2092 based amplifiers?
Did you try it with a speaker/resistor at the output?
If not, try it with a 8R resistor.
Without resistive load some output filters show pretty impressive
currents when the 2092 starts to oscillate...
Unfortunately there could be many other reasons.
The IR shut down functions are great - but the downside is that many
imperfections can trigger them.
If not, try it with a 8R resistor.
Without resistive load some output filters show pretty impressive
currents when the 2092 starts to oscillate...
Unfortunately there could be many other reasons.
The IR shut down functions are great - but the downside is that many
imperfections can trigger them.
I would suggest checking the output mosfets. Probable shorted S to D
If these have gone they sometimes take the 2092 with them and simply replacing the 2092 blows it again.
When you test the 2092 make sure you have a load connected otherwise I found it wouldn't start up and would simply put +17v on the output.
Also if the 2092 do start up with no load you could possibly kill the output filter capacitor as the choke rings at very high voltages.
If these have gone they sometimes take the 2092 with them and simply replacing the 2092 blows it again.
When you test the 2092 make sure you have a load connected otherwise I found it wouldn't start up and would simply put +17v on the output.
Also if the 2092 do start up with no load you could possibly kill the output filter capacitor as the choke rings at very high voltages.
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Ive been through everything. changed FETs, checked loads, added/removed loads.
I could not figure it out. So I contacted Peavey. They sent me a schematic, I discovered an error in the schematic and thats when I decided to check the schematic against the PCB, and it was the same! They had the overcurrent shutdown resistor of 10K connected to gate drive, Basically between pins 16 and 14. 14 being HO. Of course this is wrong, and its wrong against every IRS2092 variant design I had come across.
So i moved the resistor into the correct location on pin 15. instead of 14. Worked perfectly after that change. Funny thing is, the matching PV115 speaker has the same error and it still works. I performed the same modification and didnt break anything. Still working.
BTW I am aware of DC Offset issues when using an unloaded output, and unloaded outputs with class-D amps in general are a bad thing...
I could not figure it out. So I contacted Peavey. They sent me a schematic, I discovered an error in the schematic and thats when I decided to check the schematic against the PCB, and it was the same! They had the overcurrent shutdown resistor of 10K connected to gate drive, Basically between pins 16 and 14. 14 being HO. Of course this is wrong, and its wrong against every IRS2092 variant design I had come across.
So i moved the resistor into the correct location on pin 15. instead of 14. Worked perfectly after that change. Funny thing is, the matching PV115 speaker has the same error and it still works. I performed the same modification and didnt break anything. Still working.
BTW I am aware of DC Offset issues when using an unloaded output, and unloaded outputs with class-D amps in general are a bad thing...
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First of all: My congrats - you made it!
Or intensional, but living on the edge.
Interesting variant - not sure if this was a real error.
Or intensional, but living on the edge.
IMHO valid only for messy designs (which you find a lot out there).
D
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