What's Inside/No FCC ID?

A project log for Reverse Engineering The Midland WR120-EZ

Attempting to re-band the radio into the ham band as well as develop a tool for backup and restore via serial using the built-in clone port.

Signals Everywhere/KR0SIVSignals Everywhere/KR0SIV 07/20/2017 at 02:382 Comments

Normally when working on any electronics project the first thing I do is grab the FCC ID. Something everything with some type of radio will have and nearly any electronic device as well. A company like Midland not having such an ID struck me as odd.

Nevertheless I started tearing into it and seeing what there was to this odd little radio.

Here is what I found

Masked CPU

Masked CPUSeveral Test Points but no other indications

Unknown Chip With Test pads

Unknown chipTest pads check voltage, no indication of data

Finally, something I can play with. A Winbond flash memory chip.

Winbond 25x40bvnig 8SOIC ChipWinbond 25x40bvnig 8SOIC Chip : Click for datasheet

A UTC petw chip used as an audio amplifier for the Alerts

UTC ChipUTC MC34119L: Click for datasheet

Possible JTAG Header


Charlie Ramirez Animation Studios de Mexico wrote 10/17/2020 at 22:35 point

Update: I have disconnected the strange jumper from the TEST terminals and nothing seems to have happened. I will update if I discover something different but so far it seems that they are only empty terminals

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Charlie Ramirez Animation Studios de Mexico wrote 10/17/2020 at 21:39 point

Interesting, playing around with it a bit, I managed to find something strange about the "Unknown chip with test pads":

I bought my WR120 second hand, (since in Mexico they are somewhat difficult to find). and trying to see if i could modify the Notification Tone to use the official tone of the Mexican seismic alert system, Compare the images. but apparently someone repaired it before or from the factory came with this. the "TEST" terminals are bridged with a wire to a pin below C21, and there is something strange about the arrangement in the smd solder between R48 and C6
the wire is glued to the pcb with some kind of paste (maybe hot glue or flux that has solidified)

-I leave you images:

I don't know if I disconnect the jumper from the TEST terminals or leave it as is?

The radio works but behaves somewhat strange when operating on batteries (these drain in a few months, the screen becomes dim but fluctuates to the rhythm of the message when listening is active)
 I do not know if it is because of it, but if you connect headphones to the external alert port you can hear the transmission faintly.

As an accidental discovery, it is possible to generate some strange behavior when inputting audio through the external antenna and cloning ports.
-I discovered this by accident trying to do an auto activation with windows audio and EAS tones, the strangest occur when changing the sampling frequency to 44100 and 16 bit audio, apparently the radio must have some built-in filter of bands, since more bits or frequencies seem unfazed, apparently Self-Act. it can only be done with old iphone

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