PM2 displays wrong pace

[Hans]

I am working on a PM2 Rev. 2.1 for a long time now.. Lot of cleaning with vinegar, drying with the hairdryer and
cleaning a lot of copper tracks. Must have spent more then 12 hours already.

First the PM2 did nothing at all, but after doing the activities as told above, it started working.

Then i found out that the pace (spm) was not accurate. From 77 to 25, then - - and all in between. Also
the pace per 500 mtr ( /500) was making jumps, not stable.

Then, a long story .. , the C1, connection at the right going up to the via near c8, appeared to be loose (
it broke loose with soldering).

Later i removed the whole C1 from the board. And to my surprise .. the PM2 was still working! but withe the
problems mentioned above.

Maybe there is someone who can answer my questions ? I would be grateful.

Has anyone ever come across the same problem? And is it likely that soldering a new C1 to the board will
fix the problem? I am posting this from the Netherlands where it is not possible to buy these components for
the PM2. Anyone any idea where to find the component?

In a version 2.3 i saw that there was no C1 at all on the board, i wonder what the functionality of the C1 is.

A lot of questions, for some maybe an interesting story ?

Kind regards,
Hans

[lindsayh]

over to you Carl Watts!!

[Carl Watts]

LOL

Well your keen to spend 12 hours on one of these, I must admit the first one I did took like 4 hours, the occasional one now takes a couple of hours or much less.

C1 is often cracked if you look at it closely, it can cause high current drain but it will not cause the problem you describe.

Corrosion causes all sorts of issues and the trick is to make an early call so you don't waste alot of time on it. Basically about 10% of the PM2's I see are a write off.

Cannot say I have had one with your exact issues.

Check you have +3V on the +3D point at the left of the inductor L1, this should stay at 3V with a battery voltage of 1.5 to 3.4V.

Check you have 3V getting to the top of the board across C15 on the yellow Tant.

Any corrosion on U13 ? This Op-Amp takes the tiny millivolt pulse from the pickup and converts it to a square wave thats fed into the Micro.This is the likely;y cause of your problems.

Usually its still a copper track or a via thats gone open circuit. Have you still got a low resistance path from the negative battery terminal to the Via to the right of C1 ?

Most of the time the problem is below the battery terminals where the acid runs down the board.

Also you may think thats the only problem but quite often even with it "Working" the run and standby current is too high and it kills your batteries, You need a meter that can read the typical standby current of 0.064mA to a run current of less than 3mA with a 3V supply to the board.

I presume you have Model C rower, are the three magnets that are embedded in the flywheel okay ? You cannot use a PM2 monitor on a Model D rower.

Feel free to PM me and I will send you my e-mail address so you can send me a picture of the board.

[Hans]

Thank you Lindsayh.

Carl,
Thank you so much for taking Your time to answer this old message. I Pm'd you About this a year ago, uninvited, and now you answer. I am so grateful.
Maybe i'll come back later to you on this issue.
Again,
Thank you.
Hans