I haven't been able to work on this for a while but the voltage between pins 1 and 4 is 5.0. I've rechecked the solder joints and the D- and D+ pins now have 1.94 when using 2 AA Duracell Alkalline batteries (1.4 and 1.5v). However, inspite of the voltages being the proper values, my iPhone 3G doesn't start charging. Another Minty Boost has the same voltages and does start charging my iPhone 3G.
Now, I'm puzzled. Any suggestions would be appreciated.