Model C Speed Sensor Pickup Problem

[rakserv]

Hello -
I just picked up a Model C with a PM3 performance monitor, the place i bought it from had just replaced the monitor pickup sensor and cable.
... it was working for a bit, i was able to measure drag factor, overhaul the machine (take it down to box frame, upgrade the drive train (new axle, sprocket, chain, and idler pulleys), put it back together measure the drag factor again (222).

i was having some problems with the PM3, i had to use the reset button to wake it up. so i installed a different PM3 on the model c and suddenly the PM3 is not displaying any information when rowing on the model C.

what i've done so far:
- i checked the both PM3 monitor settings and the machine type is set to Model B/C
- i installed the both monitors on a model e with them set to machine type D/E they both pickup signals from the model and the monitors display correctly
- i removed the flywheel and made sure that the back surface is clean where it passes over the sensor

i am admittedly a bit perplexed at what to do next.

any feedback or ideas would be appreciated.
thanks,
-rob

[Citroen]

Have you programmed the PM3 for model C on the hidden menu?
http://www.concept2.com/service/monitor ... stuck-zero

Does your DVM (on resitance / continuity) show open circuit when connected to the tip & ring on the sensor jack?
Is the 2.5mm socket loose from the PM3 circuit board?

[Carl Watts]

The model C Tach pickup sensor is just a coil of wire.

If you have a multimeter it will measure about 105 Ohms plus or minus a couple of ohms.

Usually you can get a break in the wire at the connector or another common problem is actually the tach sensor socket in the PM3 can become intermittent.

The Model C pickup is more reliable than the Model D pickup as it is just two wires and not three. The ratio of cable replacements for me is like 10 to 1.

[rakserv]

Thanks for your suggestions, responses below.

Have you programmed the PM3 for model C on the hidden menu?
http://www.concept2.com/service/monitor ... stuck-zero

yes, the PM3 was working and then it stopped working. the replacement PM3 was set to machine type B/C and verified looking at the Product ID information through the utilities menu.

Does your DVM (on resitance / continuity) show open circuit when connected to the tip & ring on the sensor jack?

resistance measurements:
measuring the resistance of the monitor sensor wire from the PM input jack to the metal sensor on the flywheel end, i get an open circuit indication.

Is the 2.5mm socket loose from the PM3 circuit board?

NO, i have used two separate PM3s that both fail on the model C but work fine on a model E

So it looks like a bad Monitor Pickup, which I didn't really think it would be since the part was just replaced a month ago

[rakserv]

As always, thanks Carl for your feedback and suggestions.

The model C Tach pickup sensor is just a coil of wire.

If you have a multimeter it will measure about 105 Ohms plus or minus a couple of ohms.

Usually you can get a break in the wire at the connector or another common problem is actually the tach sensor socket in the PM3 can become intermittent.

The Model C pickup is more reliable than the Model D pickup as it is just two wires and not three. The ratio of cable replacements for me is like 10 to 1.

If you have a multimeter it will measure about 105 Ohms plus or minus a couple of ohms.

It measures as an open circuit from the PM input jack to the metal sensor at the flywheel end.

Usually you can get a break in the wire at the connector

which connector end ? (PM input jack or Flywheel Sensor end) Is it something that i can repair ?

[Carl Watts]

Put the meter across the tach pickup connector. Its quite hard to get a good connection. Get a second person to wiggle the cable while you hold both meter leads on it.

They are as cheap as chips in the USA, just by a new one. I only repair them in NZ because the local distributor price is hideous.

[rakserv]

I thought i had resolved this issue, received a new Monitor Pickup cable and installed it. The cable has now been replaced twice in the past six months, most recently on sunday (12/10/2017) and it seems to have once again failed.

After I installed the new monitor pickup cable and screw kit on sunday evening, all was well. all the PMs that i checked it with (2-PM3s and 1-PM4) all worked fine.

I just now set the rower up and tried to use it and with PM3s found that the PMs do not register any data when pulling the handle.

I am perplexed as to what could be causing the Monitor Pickup Cables to fail

Any thoughts or ideas would be welcome.

Monitor Pickup and Screw Kit—Model A, C
Part Number: 1748

For use with Model A and C Indoor Rowers. This is the pickup (sensor) and cable (wire) that transmit flywheel to the Performance Monitor on your indoor rower. If your monitor lights up with zeros but the display does not change when you begin rowing, you may need to replace this part. If the cable or cable housing is cut or broken you will definitely need to replace this part.

[Carl Watts]

Check the 3 magnets in the flywheel.

Also the distance the face of the flywheel to the pickup is important, those magnets are only small. The nuts on both sides of the shaft need to be done up all the way.

Check the magnets with a paper clip, there should be "Attraction" there. Any rust can get through the magnet nickel plating and then the magnet goes weak and actually just falls to bits.

The pickup is fine, your problem is elsewhere

[rakserv]

thanks carl ...

can you think of any reason that this might be killing PMs as well ?

[Citroen]

thanks carl ...

can you think of any reason that this might be killing PMs as well ?

No. The signal from the hall-effect sensor doesn't have a high enough current. https://en.wikipedia.org/wiki/Hall_effect_sensor

PMs usually die because of battery leakage, the supercap going dead, torn off USB-B socket and other physical damage to the circuit board.

[rakserv]

thanks carl ...

can you think of any reason that this might be killing PMs as well ?

No. The signal from the hall-effect sensor doesn't have a high enough current. https://en.wikipedia.org/wiki/Hall_effect_sensor

PMs usually die because of battery leakage, the supercap going dead, torn off USB-B socket and other physical damage to the circuit board.

yes, the lifecycle of PMs is somewhat temperamental, but i have had two (2) different PMs stop working (dead no boot dead) after being used on this rower for testing for a short period of time. I am not certain that they are related, but in the world of electronics coincidences are always suspicious... Just looking for some thoughts on how continue without risking more PM failures.

[Carl Watts]

The sockets on the monitors give problems, especially if its been an ex-gym or ex-rowing club machine.

The sockets come loose on the board and also they crack in half. Corrosion on the PM2 & 3 stops the pickup from registering your rowing, this is a very common problem.

The pickups do not "Kill" your monitor, its people and environmental conditions that kill the monitor.

The monitor is very vulnerable to moisture and battery acid leaks, they fail on a regular basis, I know I repair them.

[rakserv]

well, i was at a loss;
- i tried several things, to get the performance monitor to receive the signal; attempting to snug up the flywheel to closer to the pickup, tapping the axle shaft further into the box box frame, including installing a different model C flywheel: NO JOY
- i opened the speed sensor, saw the coil and wire. i measured the resistance between the plug-in jack and the wire input to the coil and received a reading of 0 ohms

so i ordered a new speed sensor pickup and installed it; and it worked! PM2 and PM3 both worked fine.

seems very weird to me and i kept the old speed sensor pickups and plan to try them on other model C's as i get an opportunity.

very weird.

[Ridgers]

Looks like I’ve hit a similar problem.
Newish sensor fitted (probably around 50k ago).
Old pm2 worked fine for a while then seemed to give some erratic / irregularities readings. Eventually no response to rowing even though screen would switch on ‘mechanically’ (not automatically on starting rowing)
Magnets are good (although the strength is not massively strong they have ‘attraction’ to the paper clip Carl spoke about)
Concluded it was probably the (old) corrosion damage in the PM2 as sensor provided around 105 ohms.
Just purchased new pm5. Plugged in to test and no reading - followed the advice on start up including removing batteries, still no response.
Basically wondering if you managed to get continued success with the new sensor? ...
did you get to retest the old sensors?
I’m reluctant to buy another one so soon

[rakserv]

I have not seen any issues with the machine with the updated tachometer pickup speed sensor.

I have no idea the root cause of problem ... after logical troubleshooting was exhausted just replaced parts until it worked.

I am working on refurbishing a couple of model Cs this weekend, if I have time I’ll see if the speed sensor that I replaced works on one of the refurb machines.