PD9245C-14.8

Thanks - you inspired me to work to lower the 14.8V output of my "C" model to get it back down to the lower stock boost voltage of 14.4 which is going to serve as my new lithium bulk charge source (hopefully working as well as the 14.8 did for my GC2s). Note here that I only use the PD for boost alone powered by a wind-up timer while running the genset. I initially worked to design a solution that had variable output by installing the pot on the rear and running a very thin shielded cable from the 50K POT to near the DC side where the microprocessors and DC output was provided. (Back of unit faces toward me in implementation.) In my mind it was of course a work of art-work until I discovered the unit goes into bad oscillation unless the resistor is soldered right on the board. Then I wasted another half day before realizing that there is so much RFI pouring out of the device open case that it was making my digital multi meter go insane each time I tested the feature I had added. Turns out I should have put the case back on and tested it but after working on it about 8 hours, I got fed up with the constant oscillation (makes a squealing sound in the transformer) that I just soldered the stock value 34K resistor back to the board and at 14.37 would just call it a wrap.

I was quite confident I had ruined the power supply because my DVOM was scaling all over the place even with the resistor soldered right to the board. Then I simply put the PD case back on with the stock resistor and it was stable. Settled right back down with the case on. So will a pot work on this? Answer is that's extremely doubtful it would work even if testing it with the case closed and this is due to the large amount of RFI swirling around inside that case. On super close inspection, I see they even have a ground "tab" on the PCB running under that resistor which I assume is a late-add engineering change to try to keep some of that RFI out of the microprocessor pin which causes the oscillation you hear as the unit is powered down.

Now I must warn anyone who attempts this, if you are old-school and even if you have modern equipment, these components are all micro, for example the resistor in question is smaller than the tip of a fountain pen and you can destroy the board unless you have either a magnifying board camera or jeweler's glasses on. It's not easy and good chance there are only about 3 resistor swaps opportunities before you have destroyed the board. I got extremely lucky but for others, I don't recommend attempting this unless you have experience working with boards with micro components and have jewelers tools and a tiny soldering iron. Anyway thanks _ _ _ I'm "set" again until something else goes wrong.