[hpsdr] Tapr hombrew hermes shutdown problem

[Oliver Goldenstein]

Hi All !

I am having a problem since sunday. I am not making progress in debugging
the error. Hermes ran nearly the whole weekend during the contest. The
enclosure was warm but not hot.

The problem:

The board starts fine es every time and i can run it for lets say  one
minute with cuSDR64, ghpsdr3. After the minute the leds are only showing
half of the light than before. the board is then no more reachable and
cannot be discovered. When i start the board  in bootloader mode everything
is normal. When i remove the jumper and powercycle the board it runs also
fine just to the time i put the networkcable in. it seems that network
traffic can speed up that failure.

I measured as follows:

U18, PIN3 = 13,6 Volt
U18, PIN2 = 11,9 Volt

in normal operation and after shutdown.

The SMPS 5V output shows 4,96 V also in normal conditions and after the
shutdown (measured at L32). So i think the 12V and 5V Buses are ok ?!

Now i measured at C153 and C174 and the input Pin of the LTC1529. During
the normal operation i have 4,45 Volt there. During the minute until the
shutdown the Voltage decreases down to 2,83 Volt in 0,01 Volt steps. The
last steps are faster.

When i understand the schematics right i should have the same voltage at
the end of L32 and at C153.

This must be something serious or silly. I hope the last one.

In bootloader mode i am able to program and successfully reprogrammed the
board back to 2.2 which results in the same behaviour.

73 Oliver DL6KBG
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