Troubleshooting ACT8846 IC, power cycling.

Thread Starter

Yami

Joined Jan 18, 2016
309
Hi guys,
I am trying to troubleshoot a guitar pedal board which has got a Rock2 SoM module (its based on the Rockchip RK328). The unit shuts down on start up. It has got a ‘soft latching power switch’. I have two identical faulty boards same symptoms. I’m working on one board removing and re-soldering components trying to troubleshoot. I just need one working board.
There is a Mosfet used to turn on the power to the whole board. I have bypassed this and I am powering the board directly from a 12V supply. Pressing the ON button initialises the start up process just like before but instead of turning off the voltages remains. I have checked all the DC/DC converter ICs outputs and LDOs. Everything seems to be in working order.

Potential issue:
I think I have zeroed in on the problem. I could be way off, but definitely something interesting. The ACT8846 chip is used as the power management IC for the module. Here’s what I noticed
There is 5V at the INL1, INL2, INL3 pins and I measured 0.3V at OUT9 and 0V at OUT8. Why I measured those first were because ‘VCCIO_PMU’ is used for the reset IC - U2207.
I was really hoping for something simple like shorted out coupling cap but it doesn’t seem to be so.

I have tried manually resetting the IC described on the page 31 on the data-sheet(ACT8846), but this was before I had the main supply latched.
I was hoping that someone could give me further advice on what to troubleshoot and what to look for? I am aware that the microprocessor could be bricked as well, any idea how to ‘un-brick’ it?

Thanks in advance for the help.

Rock2 SoM
https://wiki.radxa.com/Rock2/som

Rock2 SoM schematic
https://dl.radxa.com/rock2/docs/hw/radxa_rock2_som_140927.pdf
 

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