Tach/Pickup issue

[bloomp]

I have already run through all the steps suggested on the troubleshooting page - up to the point of swapping monitors which I can't readily do.

I went away on vacation and came back to a non-working monitor. I can program distances, but it does not pick anything up. I have checked the tach, pickup cable and resettle it all, it worked for about 1k last night after resettling it, but stopped after I had reset the monitor for a RP session.

Any suggestions? I have tried holding the tach in various other positions to see if I can get a reading while I pull small arms only strokes, but nothing changes.

Forgot to mention: I have a PM3 on a Model D, running the latest firmware (updated about 10 days ago).

[Carl Watts]

What version of firmware are you running ?

If it is V105 then you have the older version of the PM3 monitor, which I have had a couple fail with pcb problems where the copper via on the board goes open circuit and you loose the tach only but everything else works fine.

Make sure on the Product ID page you have the unit set for model D/E which it should be as this is the default setting.

Unfortunatley you do really need to get another PM3 or PM4 as the fault could still be the pickup on the flywheel and another monitor would confirm this.

[Citroen]

Forgot to mention: I have a PM3 on a Model D, running the latest firmware (updated about 10 days ago).

Is it configured for a model D/E?

Main menu --> More options --> Utilities --> LCD Contrast

Once you're on the LCD Contrast menu press [CHANGE UNITS] three times, then press [CHANGE DISPLAY] three times. That brings up the hidden configuration menu. On there you can choose the model that the PM3 is configured for.

If that's correct then change the flywheel sensor assembly (or rewind the coil and replace the lead/2.5mm jack).

If that fails call C2.

[bloomp]

Yeah, I should have mentioned that I had checked the model setting as well - and Carl it is V105 on the older PM3.

I guess I'll have to find a new sensor and wire... Damn.

[bloomp]

Just ordered a new motor unit for the model D... Hopefully shipping is fast from VT to CT

[tropicalm]

Good, so far everyone with pickup cable issue has ordered a replacement part.

My PM3 is now stuck on zero after 3 years of loyal services, blah blah blah, it's my turn now...
After unsuccessfully playing with the cable and massaging it in all possible ways, I just can't get the spin movement to auto-wake up the PM3, or have the least meter counted while rowing.

This said...To the comfort of ordering a new cable (it's quite uneasy to test another PM3, would have to run to some gym at the other end of the city with my unmounted PM3, and convince the personnel over there of my dodgy experimentation's purpose...), I'd really get more excitement mending the pickup cable myself, or at least understand what part is faulty.

I removed the sensor cover, and realised the cable was soldered directly on the board, with a layer of varnish to polish it off... So I can't order just a cable, but would have to order the full generator + cable.

Since I've got advanced in Electricity, I was wondering what kind of signal I could pick at the other end, on the 2.5 mm jack, with a simple digital multimeter. I pick some current as I row, but clearly it's not good enough.

Would anyone here have the pinning specs at the PM3 end for the jack? And awaited current specs?

Sorry, I like the excitement of System D. Feel that adrenaline flow when you realised you proved yourself you needed to place a one-click order for a new part...

[Carl Watts]

What version of the PM3 do you have ? look at the product ID screen.

I have not had a chance to look at what signal comes back from the model D, iirc the generator in it gives you 4.5Volts dc when you row to power the monitor and recharge the battery if you have a PM4.

I have had several older versions of the PM3 that looses the tach signal output from the Op Amp.

Take the PM3 appart and inspect the underside of the board, if there is any sign of corrosion on it you have lost the tach output.

Also pays to first check the settings of it first to see it is set to Model D/E or it will not work either.

[tropicalm]

Hi Carl,

I've got PM3 Hardware v461.
I've checked that the type D/E matches the machine too.

I've found that I've got an DC output from the jack connecter of the cable that's capped at exactly 4.0 V, however hard I row. It seems that only 2 wires are used, out of the 3 available in the cable.

Once plugged into the PM3, it falls at around 2V on the female connector pins on the PM3 board;
maybe because it's under charge then, by all the electronics behind? Or maybe because there's some resistance happening on the inners of the female connecter...
In which case I was wondering what could be the sufficient condition for the wake-up interrupt of the PM3.
Is it a sufficient voltage? As I've noticed it was not waking up either, of course...

My problem arose just after downloading the data to my PC, like I do regularly.
Then, out of the blue, after a first failure, the meters counted for a few seconds, so I got all excited and ready to row, and by the time I tried again it failed again, for good this time. All the other features of the PM3 work, including the HR.

I still did around 5k, well, in time, I can only tell you the boredom of rowing blind...
I was about to plug a LED to the coil to have some materialisation of my work...

I can't wait to go and do the experiment tomorrow at the gym where they have C2s.

Anyway. I'll post the outcome when I have further news.

[Citroen]

Then, out of the blue, after a first failure, the meters counted for a few seconds, so I got all excited and ready to row, and by the time I tried again it failed again, for good this time. All the other features of the PM3 work, including the HR.

Check that the PM3 is configured for the right model of pickup.

Main menu --> More options --> Utilities --> LCD Contrast

Once on the LCD Contrast menu press [CHANGE UNITS] three times then press [CHANGE DISPLAY] three times. That brings up the hidden menu.

[tropicalm]

Yes, I've done this check too, of course. It was unprobable it was that as it didn't work from one hour to the next.

Anyway, the problem has now been fixed.

Timeline:
I went to a gym to check my PM3, worked fine. First relief...

Then I checked the direct current at the output of the generator board, and indeed I had very different voltage values than at the jack end of the cable. So I didn't look further, that was it.
I've removed about 3 inch of faulty cable (it's the start end, that S-bends through the bracket before coming out, of course...), like a surgeon removes the bad segment of a colon, and plugged the rest together, and it works.

I suggest to plug it back using some connecting bits, so that next time it happens, you just have to change the rest of the pickup cable, and not the whole thing, that includes coil, electronics and board.
Mind you, my cable is not removable (well now I've made it so), it's soldered on the board...

For the $-minded, I've also found that the 2.5 mm cable that you probably have at the back of a drawer, that comes from some old mobile phone headset, will come in handy; instead of getting one at $17, as seen today in a shop.

I also suggest to avoid folding the arm away everytime you finish using your erg, except if you can't do otherwise, as I suspect this killed the cable elbow.


For those interested in the technical details, and a possible perspective, read further:

There are 3 pins on the generator output: black, white, and red.
All voltages at this point are DC and smoothed.

On my model D, there's a constant 4.05 V DC between white and red. Not really interesting for me.
But between white and black there's a voltage that is proportional to the rotation speed of the flywheel.
The latter is really interesting for those geeks who would like to pick the voltage using an op-amp to lead it to a more exciting vu-meter, like a home-project upyard yard of blue LEDs that glows proportionnally in the darkness of your garage as you're getting excited on the handle, at 1am, while kids and wife are asleep...
Don't laugh... I've got the quad up-amps chips and leds ready, but not time to pin them on a board, because I spend that time rowing instead... Voilà...