Re: uBITX - U1 Getting Fried - possible cause #ubitx

Jerry Gaffke
 

Yup, something doesn't seem right.

From post 42723:
  I have no idea how R75 could have smoked, except maybe a catastrophic failure in the TDA2822M 
shorted that (normally) input pin to Vcc somehow.

And this from 43122:
  I fried mine when I plugged in a stereo sony noise canceling headset.
So it does not only happen with mono plugs.

And this from 43170:
   Last evening he turned his radio on and the TDA got very hot
and started smoking for no reason at all.

And this from 43211:
   Recently I found some TDA2822's on ebay from China, I got the GQRP club to purchase a batch ( I bought 50 too ). Tony Fishpool (G4WIF) setup up a test and found although they worked well at low Volts they got hot over 7V!:

Might be a few weird ones, I didn't do an exhaustive search.

A 6v regulator to feed the TDA2822 might be our best bet.

Jerry, KE7ER



On Thu, Mar 1, 2018 at 09:41 pm, Vince Vielhaber wrote:
Something doesn't seem right here. At least one person said that the IC smoked as well as R75. R75 is a 2.2 Ohm resistor connected between pin 6 and ground. Pin 6 is the + input on amp #2.

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