Hardware Troubleshooting: Fetch 1501 Main Board - 24V Rail Not Activating

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Hey everyone,

​I’m currently doing a deep-dive hardware diagnosis on a Fetch 1501-0000 and could use some insight from anyone familiar with the proprietary power distribution logic on these boards.

Fixing to put on market f

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or sale.

​Current Status & Symptoms:

​Power Input: I’m successfully getting 48V in to the main board. PC has been powered and verified working. The main board won’t power on the PC when switched on. No voltage reading at PC jack.

According to Fetch documentation, charger voltage input should power on the robot even with end of life batteries.

Hardware verified functional: e stop, power breaker on off switch, power button, fuses, temp sensors.

No enable voltage at pins 4 of U17 PS2492 chip. Should be powered by STM32 chip which is getting power. 48V at left side capacitors of U9 DRV8301 chip. 0.5V at right side caps.

​LED Indicators: I have a solid Green LED at D44, accompanied by a blinking Blue LED at D58.

Area where U9 chip is had oily substance that seemed to be from thermal pad. Area cleaned with 99% alcohol. Cleaning shows changes in resistance to PC power pins.

​The Issue: Despite having the 48V input and the green status light, I cannot get the 24V rail to activate.

​Does anyone know exactly what hardware fault or missing handshake the blinking blue light indicates on this specific board? I am trying to figure out what internal safety loop is keeping the 24V rail locked out.

​If anyone has hardware documentation, pinouts for the power headers, or has bypassed this specific power state before, I’d appreciate the pointers. Any interested takers welcome as well.

​Thanks in advance.

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Generally we send ROS debugging questions to Zulip or Robotics Stack Exchange, but this one seems pretty interesting so I’ll let it slide this one time. :wink:

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How did you get robot 0000? AFAIK that robot wasn’t sold? Did you press the computer power button on the side of the robot, there is a breaker switch and a computer power button.

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My spider senses are undefeated.

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Did it fall off a truck at some point?

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Are you serious assuming I skipped the things people with basic skills only know how to do?

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Anyway. If you have information regarding the topic give it. Otherwise shush. People questioning me how I obtain my possessions and suggestion the use of a power button sound ridiculous.

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Spider senses? Humans have spider senses? Is that what robot engineers believe? Can robots come with spider senses?

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The creativity here. Imagination is key for engineering I guess. Sounds like the plot to a cartoon. A robot falls off a truck and got an ouweee. Mommy didn’t notice the robot go missing, she was too busy looking for a new job. The sad little robot went autonomously about in search of someone to repair the ouwee. Noticing a big pile of electronics the robot thought it found a new home. As the robot approached it’s new home the batteries ran out of juice. Poor little robot, with it’s batteries dead and mommy at her new job, who was there to save it…

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Wait I have a better one. Fetch wasn’t happy with the new home it had. The new mommy didn’t care for Fetch. With its bulky design, slow movement and crappy heat dissipation solution on the main board, she chose to throw it to the trash. Fetch missed it’s first mommy. On the way to the trash, Fetch rolls off the truck on an ambitious journey to find it’s old mommy.

I should see if the people I knew at Pixar would love this

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heh, I was asking how you got the robot because I founded the company and designed that robot with my friends. but hey wtf do i know. nice story, good luck, all the best.

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