Fixing Blue ESR Meter
Here is an email that i got from one of my ERG member who has successfully built the Blue ESR Meter Kitset. He is a beginner and progress very fast and if you are a beginner too, read his explanation in building the Blue ESR meter.
Wednesday, October 15, 2008
My weekend experience with assembling the Blue ESR Meter Kit was very educational.
It was a SUCCESS, after a small amount of trouble.
The Meter was assembled over last Sunday and this Monday.
I read and followed the instructions……testing, & installing 4 to 5 components at a time.
1. On Sunday, after soldering the 1% and 5% components …… I learnt that for PCB work, it is much better to use 0.7mm sized rosin core solder 60/40.
Monday I bought 1lb of 0.7mm solder to replace the bigger (mm) size I had used on Sunday. I was then able to make professional looking soldering connections FAST.
2. Sunday, I also learnt that my Extech 470 Meter can only measure capacitors through its Auto ranging function. I cannot manually change the range. The meter didn’t correctly report the value of the three 100uF 16V RB electrolytic capacitors. (C1, C3, C9)
This surprised me UNTIL I rechecked the. Meter’s maximum capacitance measuring range & learnt it was up to 100uF with resolution of 0.1uF, and accuracy of +/- (5.0% reading + 5 digits).
I guess this meant that if E-caps were greater than 100uF, the meter wouldn’t respond.
3. When installing parts onto a PCB , always start with smallest, non-polarized, THEN install polarized parts, followed by larger parts, & THEN static sensitive parts.
When all parts on the PCB were finished installing, the meter didn’t work as described in the “Initial Checks” section of assembly manual.
I was upset, and started to doubt myself. (Even though during installation, I didn’t mix-up the parts)
I wanted to write you, but remembered that you said everybody must develop their own mental strength of doing diagnostic work. + You and ANATEK Corp. already gave me everything I needed.
So I started by setting up ESR Meter so that I could use firmware to allow the microcontroller to do some basic testing.
Result showed code F7: Q3 not sourcing current.
Manual suggested I Check around Q3 (2N3906), R5 (2.2k 5%), R6 (10k) and pin 15 of IC2.
I decided to stop at that point.
So, I walked away, calmed down & on Tuesday tried to think more about my observations & what they could tell me in combination with Blue ESR Assembly Manual.
Tuesday I studied the ESR schematic, & after checking my parts were all correctly installed, I located pin 15 of IC2 on the PCB…… and observed its relationship with R5 (2.2k); the base resistor for Q3.
Jestine imagine my surprise when poking around R5 I discovered that I could move the resistor lead within the solder.
4. I recall R5 was installed with >0.7mm solder, & I think I must have left the iron on that spot too long, because upon de-soldering …the trace pad around the lead hole immediately came off.
I considered two different fixes before continuing further diagnostic checks, and opted to bend R5 lead towards existing trace and tack solder using 0.7mm solder. (vs. jumper wire to pin 15 of IC2)
All further tests and adjustments………. (i.e. 82 ohm 1%, and 5.6 ohm 1%, and battery “b” on LED 7 segment display)………. worked fine after that.
My last problem was with 9V battery leads not staying connected after I fit the battery into its compartment, but careful arrangement of the cables solved that problem.
My Blue ESR meter now works fine.
Most important lesson I learnt is to do my best, and if things don’t work as expected be thoughtful. One (1) right answer at a time adds up to a solution.
That was a fantastic write up! By the way if you do not know what is a Blue ESR Meter you may click on THIS LINK to check it out.