Hi! happy new year with lots of successful electronic projects for all!
In the attached pictures you can see the schematic and the pcb for an esr meter i've built few years ago
this thing....never worked as it should, it seems functional but the capacitance measurement always
shows CX ----
i tried alot to troubleshoot it....measured every component for broken joints changed most of the ICs
in case of a faulty one but still it can't perform any measurement.
i've spent alot of time and effort to build this device also the component cost wasn't exactly negligible
so now it ended up one step before i salvage it and throw it to the garbage can. :/
would you like to help me save it?
P.S original project was descussed in the following Russian site **broken link removed**
The pdf is so great and looks like it offers full support for somebody who wants to build
the instrument it describes.. but how exactly it can help me?
A PCB layout that simultaneously uses SMT components, no solder mask, and is intended for assembly by hobbyists, is a recipe for disaster.
I would check for solder bridges at every SMT component using a microscope. Usually, microscopic solder whiskers or remaining flux can cause enough leakage to cause circuit problems.
There's a missing 100nF capacitor which i think it's not important,because
in the Russian site i've noticed some others they also skipped that cap, it's
underneath the micro controller next to the 22pF caps for the crystal.
other than that i can't find any problem in the smd side, since the device
turns on, how can we isolate the problem?
this is not serious obstacle, i've done it before, help others and also helped by others
to troubleshoot electronics. (only once years ago and only on this forum i had to send a
pcb to ericgibbs so he can see it from near and fix it). THANKS again ericgibbs!! isn't he moderator anymore?? :S
the instrument i've built it's years ago and happens to be useful from time to time.
i must do something, it shouldn't go wasted forgotten in a drawer, this forum is the last resort.
rethinking what you told me, i don't understand why you find a scope so mandatory! the waveform should be a square wave or something similar to that, what is
important it's if there is any oscillation...(since from what i know) these instruments
pass an ~100KHz to the capacitor under test, am i wrong on that?
the PIC microcontroller starts so i guess i don't need to measure if there's a 20MHz oscillation.
the ~100KHz test frequency should come out from the op-amp..right? if yes, where do i take
that measurement??