PM3 Issues

[ANDY2018]

Hi All

i hope someone can help, i have picked up a concept model C with a PM3 on it, however the pickup cable was broken so i have replaced the pick up and put new batteries in the PM3 but it just reads zero's!!! i have checked that it is set up for a model C and looked at the and cleaned the circuit board (dusted it) and still i cant get it to work:(
i understand there are supposed to be magnets on the fly wheel does anyone have picture of this as my flywheel does not seem to have any magnets attached to it ( i have stripped the flywheel assembly down to check it all.

Any help appreciated, Andy

[Carl Watts]

There are 3 tiny magnets embedded into the flywheel. They are about 1/8th on an inch in diameter or 3.2mm.

They are on a radius that matches the centre of the pickup that can be seen through a hole in the flywheel.

Was there any corrosion on the board ? it usually takes out the tach signal. You need to look between the rubber keypad and the board, all the corrosion happens on the component free side of the board.

The other problem is either a loose socket on the board or the socket is cracked in half if you look at it closely.

What is the firmware version of your monitor in the product ID screen ? The older version of the PM3 has corrosion issues.

The three faults above account for 95% of "Rowing but nothing changing on the monitor" as long as you have the monitor set to the right model of rower.

[ANDY2018]

Thanks for the quick reply
The Firmware version is 311 and the hardware version is 321
I’m just going to pull it apart again to look behind the rubber pad
Is it possible to replace the magnets if they are very weak
Cheers Andy

[ANDY2018]

Have now checked the board for corrosion and there is none. Infact the inside looks new, checked the jack plug socket and this looks aokay no splits plug fits snugly. How can I check if there is a signal from the pickup? I do have a multimeter and various connectors but what am I looking for amps ohms etc
Cheers again for any help

[Ombrax]

Andy, when you say "it just reads zeros," do you mean that the PM displays zeros and doesn't respond to your inputs on the keypad by changing modes, or does it behave as it should but doesn't register any input from the flywheel?

[ANDY2018]

It doesn’t respond to inputs from the flywheel

[ANDY2018]

If there is an output from the flywheel

[Ombrax]

Does it behave as it should (i.e. change screens and menus) when you press the buttons on the keypad?

[Carl Watts]

The Model C pickup will read about 105 Ohms, it is simply a coil of fine wire.

You put a multimeter between the two metal bands on the mono plug.

You have the later version of the PM3 monitor, they are very reliable but check the socket is not loose on the board. it may look attached but its making intermittant contact.

Its unlikely that all 3 magnets have failed. I did get caught out with one in that just one magnet was okay so the monitor turned on when you rowed but still did not read.

You can check the magnets, just get a paper clip and see that it sticks. The magnets only fail if there is significant corrosion on the rower, basically the nickel coating on the magnets gets compromised and the magnet then just disintegrates. Probably not an issue in many parts of the world but we get consistent high humidity here.

The flywheel nuts need to be up tight or if the flywheel moves too far from the magnets you will have issues.

[ANDY2018]

Thanks for the replies
All the buttons operate as they should, when you say 105 ohms is this when a magnet is present or not? Going to strip it down again today and have a look at the magnets etc
Will keep this post updated as to what’s happening

[Ombrax]

when you say 105 ohms is this when a magnet is present or not?

Unlike Carl, I'm not an expert on this, but I'm pretty sure the resistance in the sensor loop isn't affected by the whether or not the magnets are present or their condition.

I imagine the system measures the flywheel rpm by counting the electric pulses induced in the coil each time a permanent magnet goes by. (I'm not 100% sure about that, but Carl will confirm or correct my guess.)

[ANDY2018]

Have tested the pickup 110ohms magnets barely hold a paper clip
Looks like a new unit or a repair where’s best in the UK???

[Carl Watts]

Have tested the pickup 110ohms magnets barely hold a paper clip
Looks like a new unit or a repair where’s best in the UK???

Those magnets are not strong, probably ok.

The coil is fine, makes no difference if the magnet is present on it or not. Basically the moving magnet past the coil induces a tiny millivolt "Spike" that the monitor amplifies and uses to work out the RPM's and acceleration/deceleration of the flywheel.

If I was you just get hold of a new monitor or if you know someone who goes to a gym with a model C just unplug theirs and plug in yours and get someone to pull the handle to check it.

Look on EBay there is a guy by the name of Simon who repairs them in the UK.

Chances are your monitor is faulty. Personally I have a spare monitor and 3 Ergs now. If your serious about the rowing you need spares so you don't miss your training, I would buy a new PM5 anyway.

[Dancer Don]

So the new pickup reads 110 ohms, and the magnets seem fine. A couple more quick things I could suggest you check:

1) PM3 has a 3 conductor (stereo) plug. C pickup has a 2 conductor (mono) plug. Make sure the plug is inserted all the way in.
2) If this doesn't work, use ohm meter and make sure the pickup jack is making contact to the plug.

[nb99]

Hi

Coming to this conversation a little late but the info has been very helpful in my case. I'm on PM3 with a model C. About 5 years ago I started getting some strange readings on the erg so replaced the pickup sensor. Problem sorted. I kept the old one in case it might come in handy again. Yesterday the new one failed completely. Monitor is fine, just gets no readings from the wheel. I get zero ohms reading from the newer, dead one. No obvious wear on the cable. From the old one I get varying readings from 110 ohms, then dropping right off etc. I suspect it's an internal cabling issue.

For now, the old one is working fine but I guess soon I will get more ghost numbers and will have to replace it too. Given Concept2 are out of stock of new sensors for another couple of weeks, I'd like to try to cut the wires on the two I have to try to build one good working one.

My questions are:
1) Is this doable given the types of cabling/sensor etc I'll find inside?
2) Based on the newer one given zero ohms reading, can you speculate what might be broken? I need to work out the most likely issues with the 2 sensors which will help me work out which bit of the pickup and cable needs to be replaced.

Thanks for any thoughts/observations.

NB