Rotary encoder defective, issues tuning C5

[libc]

Hello,

I've run into a couple of issues with my kit I could use some help with.

First, the rotary encoder's push button doesn't work to power on or bring up the menu. As far as I can tell the part is defective. The 2 pins for the button (opposite the 3 smaller pins) measure 1 megaohm between them when not pressed and there's no change when pressing it. I can successfully power the device on and bring up the menu by shorting the pins with a conductor so the rest of the circuit seems fine. Is there any way I could fix this without desoldering the whole encoder, maybe heating it or something? Try to get some contact cleaner inside it? Since it is just the built in push button that doesn't work it seems like it'd be easier to just wire up a separate button and solder the leads to the legs of the encoder.

Second issue I'm having is adjusting the compensating capacitors. For the first step the display was similar to the "not enough" image from the instructions and adjusting C8 did nothing until I soldered a twisted wire to the legs of C6 as described here: viewtopic.php?f=19&t=1108 This over-corrected the image so I trimmed the wire down until I could get a square wave with C8. For the 2nd step the display is similar to the "too much" image and adjusting C5 does nothing. From reading the other threads it sounds like I need to either raise C5 or lower C4. Since I don't have a <3pF cap available I tried soldering a twisted wire on top of C5 but the waveform didn't change, I think because it is not enough capacitance still. I'm going to try again with a different wire but I'm not sure this is even the right way to solve this. Maybe it would be easier to replace C4 with a twisted wire instead. It is just the 2nd part of the adjustment I need to do still, the first part is fine now.

Last question: For R32, I've read through the datasheet for battery charger and if I'm understanding it correctly, if I wanted to set the charge current to roughly ~500mA then I'd need a ~2k resistor, is that correct? I forget what the exact values I calculated were but it was something close to that.

[libc]

Replaced C4 with a twisted wire cap. C5 still wasn't having any effect even after getting nearly the correct waveform by trimming the wire. Then I noticed the little ceramic disc that sits under the screw is missing on C5...that's probably why it didn't work in the first place... Never noticed it before but in a pic of the board I took earlier in the build it is there. No idea when or how it fell out. Looks like I have to replace C5 now too. What kind of part do I need?

[jye1]

For the charging current you are right. You need a 2K resistor for 500mA charging current. But remember there is already a 10K resistor between pin5 and ground on BOB2. So to get 2K you need install a 2.5K for R32.

For the calibrating issue if the trimmer are shipped defective please contact us at jyetech@163.com for replacement.

[libc]

Thanks, I will send an email with about the trimmer. What about the rotary encoder?