Alexander,
Sorry that you ran into trouble with your QDX. I think the first place to look is whether or not Q7, the reverse polarity protection FET has shorted to ground. That would give you the low Ohm reading at the power socket.?
If it is the culprit, then it would be best to remove it from the circuit board and see if there's still a low resistance at the input to the 5V regulator, IC2, mainly to ascertain whether or not there is a problem with 12/9V distribution in the unit.?
If there's a reasonable resistance reading at the input to the regulator, I've read others suggesting to jumper across Q7 to reestablish operation of the unit. Of course, care must be taken to make sure correct polarity is observer. Another suggestion is to replace Q7 with a diode rated at more than 1 amp.
I hope that helps! I'm sure others with more troubleshooting experience will help.
--Al
WD4AH?
