HERCULES_SAFETY_MCU_DEMOS: Arm-based microcontrollers forum

Marco Mecha

Part Number: HERCULES_SAFETY_MCU_DEMOS

I have a problem with the board power suply.
The status leds for 1v2 and 3v3 are not turning on

When power is disconected:

TP16 TP17 TP20 TP21 are al shortend to ground,
and also are the 2 sides of C45 C148 C168,
also pins A13 V16
The F1 fuse is not open

Im trying to find the issue but without a schematic its nearly imposible.

I suspect that the U39 is faulty, but i have no way to check, unles i remove it form the board but i found this realy hard.

How can i start debbugin to find the faluty component.

over 1 year ago

0 jagadish gundavarapu over 1 year ago

TI__Guru 70351 points

Hi Marco,

According to your data either 3v3 and 1v2 regulators or controller should be damaged.

(+) TMS570LC4357: Power Supply issue - Arm-based microcontrollers forum - Arm-based microcontrollers - TI E2E support forums

First let's suspect 3v3 regulator damage, please remove the regulator from the board and verify the shorts between 3v3 and GND. If there are no more shorts after removing regulator then we should need to replace the 3v3 regulator. And same process for 1v2 regulator as well.

If removing regulators doesn't help, then please verify all the parallel capacitors between 3v3 and GND to find out any capacitor is damaged or shorted.

If you confirm regulators and all the components fine but still there is a short between 3v3 and GND then we should suspect that it should be a control damage.

--
Thanks & Regards,
Jagadish.

0 Marco Mecha over 1 year ago in reply to jagadish gundavarapu

Prodigy 90 points

Hi Jagadish, tank you very much,

jagadish gundavarapu said:
then please verify all the parallel capacitors between 3v3 and GND

I have removed the C170, C168, C148 and C45 but none of them solved the short, is there any capacitor that i have forgotten or should i remove the U35 regulator next.

0 jagadish gundavarapu over 1 year ago in reply to Marco Mecha

TI__Guru 70351 points

Hi Marco,

Try C68, and C83, they are also connected in between VCC_3V3 and GND.

If you face issue even after removing above capacitors, then problem should be with the U39/U35 regulators. U39 will convert 5V to the 3.3V and U35 will convert 3.3v to the 1.2v. So, verify the both of them.

--
Thanks & regards,
Jagadish.