Sunday 4 September 2022

Chinese RF Power Meter

My Chinese RF Power Meter has self destructed itself !

It's pretty much as this...
https://www.aliexpress.com/item/1005003572858028.html

Simply powering it on one day and the Q2 transistor glowed and let out the magic smoke.

If you have any idea what the original component marking is, I would really like to know as I can't find any detail about this bit of kit. - see EDIT at end of this post.

Click the images to go 'supersized'


The position of Q2 is just below the LCD on the right side and I have circled it's position in red on the next image after removing the LCD - it's a 3 legged device, probably SOT23...


Close up images



Beneath the top left tin screen is an AD8318 detector + circuitry.

Anyone got the same meter and could read the ID on their existing Q2 chip or better still has a schematic?
Please leave a comment below or my email is good on QRZ.com

EDIT:
Testing the AMS1117 5.0 (5v regulator) it had failed and in failing it went input to output dead short, injecting 12v to Q2 - probably why it smoked!
Q2 is/was a 3v3 regulator and tracing the circuit, it's Vout pin is also connected to the 3v3 pin at top right of the board (big clue there!).  Q2's Vin pad is destroyed, but should be simple enough to 'hot wire' to C16.
So, parts are on order, it must be worth trying to save it for the price of a coffee?


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