Someone who is familiar with this kit, would you lend some assistance?
>
> I purchased and assembled the Mk.II version of Bob Parker's widely-praised
> ESR meter kit. Assembly went swimmingly.
>
> The first test (with ICs removed) is to see what the power draw of the board
> is. It registered about 4.2 mA, whereas the instructions say that ~6.0 mA is
> typical. After installing the ICs and then doing the power-on diagnostic
> (holding the switch leads together), I get "F2" displayed on the LEDs. The
> instructions say that this means that there is a problem with the C10 cap
> charging too slowly, or not at all.
>
> Following the clues of the troubleshooting section of the instructions, I've
> unsoldered the transistors Q9, Q10, and Q11 as well as C10. The transistors
> all check OK using my DMM in diode check mode (all junctions show approx.
> 0.6v bias in one direction only).
>
> I noted on first install that some of the transistors had some adhesive
> residue from the tape that held them in a roll (I presume they were purchased
> in a roll quantity). I ignored this on first install, but cleaned all of
> these transistor leads with contact cleaner before reinstalling them.
>
> I checked C10 with my DMM in cap measure mode, and it is spot-on at 47 uF.
>
> Likewise, I removed R19, R20, and R22, examined their resistance, and
> reinstalled them.
>
> I can find nothing wrong with any of the components in this part of the
> circuit.
>
> Both ICs have 5.02v at their power pin.
>
> I've examined the solder job I did, many times, with several different power
> loupes; it's excellent. I've re-flowed all solder joints. I de-fluxed the
> board hoping that maybe the flux affected the circuit somehow. No joy.
>
> I looked at some of the points in and around these components (Q9, Q10, Q11,
> C10, R19, R20, R22) using a scope, but I'm not sure what I should see. I
> looked at pin 4 of the u-processor: it transitions irregularly a few times a
> second. Is pin 4 the u-processor sense input of the charging cap? Should this
> voltage be a ramp (slow decay) of regular period?
>
> To conclude I'll only add that I modified the board via Bob's follow-up
> instructions by replacing the 78L05 regulator with the micro-power,
> low-drop-out version (LP2950CZ-5.0) and changed R25 to 27K.
>
> Some suggestions as to what I should see at certain pins, or where to look
> next would be greatly appreciated.
>
> Thanks,
> --
> DaveC (in the USA.)
> snipped-for-privacy@bogusdomain.net
> This is an invalid return address
Hi Dave, is the fake e-mail address of one of the trolls which have been trying to destroy this newsgroup, so my filters have been deleting your posting(s). I only saw what you wrote by chance. It would be preferable to discuss your ESR meter problems by direct e-mail. You can contact me through this temporary e-mail address:
snipped-for-privacy@trashmail.net
Bob