13411Re: SDR40 v6.1 TX/RX stopped working
- Aug 2, 2007At 6:54 am ((PDT)) Wed Aug 1, 2007, ian mcphedran wrote:
>I have removed Q9 again.3.63V is too low for the potential divider U4, R35, R40, Q8 base,
>The 5V line is 4.32V, U4 is running hot, and the input current at 12.5V is
> Q9 collector pad reads 3.63V, base pad reads 0V as of course does the
so the Q9 collector node is definitely connected to something
else - I wouldn't have expected the /OE inputs of Q3
to represent a significant load, they are CMOS inputs
and hence high-impedance, aren't they?
When Q9 was hot, something was sourcing current to it:
now it's gone, something is sinking a little current from the
collector node but the high current is still flowing from U4.
The only other stray thought I have is that you are testing
in the aluminium box, the box is not isolated from supply,
and there is a short. Unlikely, but...
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