A2338 820-02020 Stuck at 5V, meter resets

[ferrc95]

The board arrived very clean, with no traces of moisture or corrosion.

Initially, a part of one of the CD3217B12s was heating up, so I purchased a new CD3217B12, which wasn't specified in the purchase announcement as being compatible with the A2338. The short circuit disappeared, but it was still stuck at 5V. So I decided to buy another CD3217B12 specific to my model, but after replacing it, it remained the same.

PPBUS_AON is 12.3V. Before the reset, it drops to 12V, remains there for a few seconds, and then drops until it restarts.

The USB power meter shows a consumption of about 177 mAh, which gradually decreases to zero and then restarts, then restarts again.

[ferrc95]

Up

[mon2]

Do not have access to my schematics and am out of the office till next week- check if there is a fuse on PPBUS_AON. Flux and remove this fuse. Then power up again. Test if this power rail is still power cycling at the producer side (before the fuse).

[ferrc95]

Hi, thanks for responding. Yes, I did the fuse removal test a few days ago and the voltage remains constant at 12.3V without resetting.

[mon2]

Measure the resistance to ground of each inductor on the board. You are on the hunt for any power rail that may have a lower than normal resistance that will denote a shorted part on that rail. List all suspects. Downstream power rails are built by using this ppbus_aon rail as the high side of the next lower voltage rail. Each is a suspect.

[ferrc95]

Hi again, I attach the resistance measurements of all the inductors.

[ferrc95]

Up

I think the problem may be in the U8100, due to the 22 Ohm resistance of the L8120 inductor.

Pd: I just saw that I put Omhs instead of Ohms in the measurements file