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Metro Mini not recognized, CP2104 chip gets quite warm
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Metro Mini not recognized, CP2104 chip gets quite warm

by elmwoodelec on Mon Jun 11, 2018 4:00 pm

Hello, we are troubleshooting a PID 2590 Metro Mini for a customer (we are a reseller).

The device powers on but is not recognized as a USB device in the Arduino IDE (pic below). We are using a known-good USB cable. We have tested on two computers, both have the requisite drivers as noted on the product page.

The soldering job looks fine (pic below)

The board feels quite warm. The CP2104 chip seems to be the source, but I am not 100% sure. We measured a max temperature of 153°F (pic below).

You'll notice the reset button has self destructed. It was not like that when we got it back from the customer, as I remember pressing it while trying to get the device to be recognized. I think it popped off when the device got warm during our testing.

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elmwoodelec
 
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Re: Metro Mini not recognized, CP2104 chip gets quite warm

by adafruit_support_carter on Tue Jun 12, 2018 11:51 am

Wow. The CP2104 is the IC on the other end of the board from the reset button. If the CP2104 is the source of the heat, it's got a long ways to go.

It does seem like something is shorting somewhere. Do you know anything about how the board was used? Did it ever work? Have you tried measuring any of the voltages on the power rails (USB, 3V, 5V)?

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Re: Metro Mini not recognized, CP2104 chip gets quite warm

by elmwoodelec on Tue Jun 12, 2018 12:37 pm

Measuring 4.9V @ USB, 4.7V on the 5V rail, 0.4V on the 3V rail.

According to the customer the unit was DOA.

elmwoodelec
 
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Re: Metro Mini not recognized, CP2104 chip gets quite warm

by adafruit_support_carter on Tue Jun 12, 2018 1:19 pm

Measuring 4.9V @ USB

This is directly tied to VBUS, so not surprising.
4.7V on the 5V rail

This is just VBUS after a diode, so not surprising.
0.4V on the 3V rail.

This, however, is the output of the 3V voltage regulator. It's also what powers the CP2104. This isn't good :(

According to the customer the unit was DOA.

Sounds like it might just be a bad unit. Send an email to support@adafruit.com with a link to this thread and they can replace it.

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