by lawndart » Thu Aug 18, 2011 3:09 am
I did Bruce's $8 mod exactly as set out in his original instructions (same 2C pack from dealextreme cells, same resistor) and used my 9x without trouble for a year.
Today I flashed the firmware to er9x. After flashing the radio still read 10.2V as usual, while my pack's actual voltage sat at 7.66V. Since this firmware allows adjusting the low battery alarm I decided to remove the 8.2kΩ resistor and have it read the pack's actual voltage. That's when things got weird.
After removing the bridging resistor the radio reads 1.2V. I inspected all the copper tracks and they seem good. I also checked the original surface-mount resistors with my multimeter and they seem okay too. I spent an hour or so trying to scrape and trace the copper tracks with a bit of solder in case there was a break I couldn't see, but the radio still reads 1.2V. Finally I decided to reinstall the 8.2kΩ resistor (which I also checked for correct resistance), but now the radio is reading 5.5V!
I'm assuming one of the surface mount resistors is not making contact but I don't know which. Based on these symptoms can one of the resistor gurus suggest a solution? For instance, if I know the the 8.2kΩ resistor makes it read 2.16V below the actual voltage, what resistor can I use to solve the problem? Thanks in advance for all assistance offered.
Dave