Post by tjmotter on Sept 19, 2019 16:13:15 GMT -5
Hmmm... You aren't going to get very far with JL401B disconnected. It supplies the 12V power to the 5.2V, 3.3V, 1.87V and 1.3V regulators. At this point I am thoroughly confused because the 1.3V regulator is the device that is supposed to be supplying power to that test point. If JL401B is disconnected, I would expect that test point to read 0. It seems like it has some kind of internal short.
If I were working on this board I would try to isolate the problem by disconnecting the most likely device. Fortunately Onkyo makes this pretty easy because they install coils on the power rail going to every major device. These coils are used as "fuses" and removing them is the easiest way to isolate a chip. Again, if it were me, I would start by removing L8302 and L8307 - this will effectively eliminate the 1.3V power to this chip. I would then install the board in the system, connect all the cables and see if the problem is still present. If it is, I would remove L8306 and L8308 next. These two coils supply the 3.3V power to this chip and re-test. If it continued clicking, I would put these coils back on and do the same thing for the VMPU. Next I would do the same thing for the DSP and would continue disconnecting power from each chip until the clicking stopped.
All of the coils are identical so you don't have to worry about mixing them up.
HTH
Todd
If I were working on this board I would try to isolate the problem by disconnecting the most likely device. Fortunately Onkyo makes this pretty easy because they install coils on the power rail going to every major device. These coils are used as "fuses" and removing them is the easiest way to isolate a chip. Again, if it were me, I would start by removing L8302 and L8307 - this will effectively eliminate the 1.3V power to this chip. I would then install the board in the system, connect all the cables and see if the problem is still present. If it is, I would remove L8306 and L8308 next. These two coils supply the 3.3V power to this chip and re-test. If it continued clicking, I would put these coils back on and do the same thing for the VMPU. Next I would do the same thing for the DSP and would continue disconnecting power from each chip until the clicking stopped.
All of the coils are identical so you don't have to worry about mixing them up.
HTH
Todd
