Erratic PM3 on Model C

Maintenance, accessories, operation. Anything to do with making your erg work.
Post Reply
11treetops
Paddler
Posts: 4
Joined: November 28th, 2019, 1:09 pm
Location: near Stroud, UK

Erratic PM3 on Model C

Post by 11treetops » November 28th, 2019, 1:48 pm

I have found some old postings about this that were inconclusive but may have missed something with an answer. Because of a series of illness and injuries and getting disheartened I haven't used my erg much for several years but have recently started again.

The strokes per minute sometimes shows a ridiculous number in the 80s or 90s when it should be about 20. Occasionally it has happened on three consecutive strokes but usually they are isolated. A few times a correct number has flashed up but been immediately replaced. When I checked the drag that was mostly sensible but with 995 sometimes occurring at both low and high drag settings.

I have opened up the PM3 to check the sensor cable socket and that looks OK. The plug on the cable looks OK. I removed the flywheel and the sensor behind it looks OK as did three little silver 'dots' on the flywheel that I assume are magnets for the sensor. I have not removed the sensor+cable.

Inside the PM3 there is a corroded capacitor but I believe that just holds enough charge to remember date, time and lifetime meters when the battery is removed for a short period - they were all lost.

The PM3 firmware is 108, hardware is 310, datecode is 0842004 and model is B/C.

I have seen postings where the cable has been replaced with no effect and others with suggestions for different firmware versions which were contradicted by someone else.

I'm reluctant to spend money on a new cable when the PM3 may be at fault but also reluctant to fit a PM5 instead as that is a lot of money without being sure of the outcome.

Does anyone know the 'right answer'? (Or should I just live with it?)

Thanks

User avatar
Citroen
SpamTeam
Posts: 5915
Joined: March 16th, 2006, 3:28 pm
Location: Basingstoke, UK

Re: Erratic PM3 on Model C

Post by Citroen » November 28th, 2019, 3:51 pm

1. Clean the flywheel pickup.
2. If #1 doesn't work replace the flywheel pickup.
3. Check the magnets on the flywheel.

The capacitor is a supercap, that keeps the volatile memory alive when the PM3 is sleeping.

Depending where in the world you're located replacing the PM3 with a shiny new PM5 may be the best option.

User avatar
Carl Watts
Half Marathon Poster
Posts: 3193
Joined: January 8th, 2010, 4:35 pm
Location: NEW ZEALAND

Re: Erratic PM3 on Model C

Post by Carl Watts » November 28th, 2019, 4:32 pm

Chances are you have corrosion on the back of the board in the TACH amplifier area which is in the lower middle part of the board.

Remove the 4 case screws, remove the 2 board screws and take out the board and between the board and the rubber keypad will be the evidence of corrosion.

Repairable if you know what your looking for or due to the age of that particular PM3, just get yourself a new PM5, especially if your in the USA as they are cheap anyway.
Carl Watts.
Age:52 Weight: 104kg Height:183cm
Concept 2 Monitor Service Technician & indoor rower.
http://log.concept2.com/profile/863525/log

11treetops
Paddler
Posts: 4
Joined: November 28th, 2019, 1:09 pm
Location: near Stroud, UK

Re: Erratic PM3 on Model C

Post by 11treetops » November 29th, 2019, 7:34 am

Thanks Citroen & Carl.

I opened up the PM3 again (and lost date, time, lifetime metres again); the board was very clean under the keyboard, no sign of corrosion.

After putting it back on the machine I tried rowing with force graph displayed. Most curves had some kind of break-up somewhere but not consistently which I think rules any flaws in my technique and strongly suggests a PM3 fault.

I'm in the UK - Gloucestershire - so a PM5 is £155. At present the fault is just an irritation so I might live with it but it's tempting and nearly Christmas.

User avatar
Carl Watts
Half Marathon Poster
Posts: 3193
Joined: January 8th, 2010, 4:35 pm
Location: NEW ZEALAND

Re: Erratic PM3 on Model C

Post by Carl Watts » November 29th, 2019, 1:42 pm

Inspect the TACH socket is it cracked or loose on the board ?
Carl Watts.
Age:52 Weight: 104kg Height:183cm
Concept 2 Monitor Service Technician & indoor rower.
http://log.concept2.com/profile/863525/log

11treetops
Paddler
Posts: 4
Joined: November 28th, 2019, 1:09 pm
Location: near Stroud, UK

Re: Erratic PM3 on Model C

Post by 11treetops » November 30th, 2019, 12:59 pm

TACH socket is good.

I think I may just put up with it unless it gets worse (or I decide I’m fit enough to consider racing - last race was BIRC 1998 in 50-54 HWT so there’s a bit of ground to make up!)

jamesg
Half Marathon Poster
Posts: 2507
Joined: March 18th, 2006, 3:44 am
Location: Trentino Italy

Re: Erratic PM3 on Model C

Post by jamesg » November 30th, 2019, 1:54 pm

I wouldn't worry, the spikes in the bar readout and the odd ratings seem to make no difference to averages.

It could be caused by mains interference, because the impulse frequency from the flywheel is close to mains frequency. The more gear I had connected to the PM3, the more spikes I saw. You could try switching off all power systems nearby.

After 10+ years I put in a PM5 and haven't seen a single spike since, and it works better too.
78y, 188cm, 87kg, last seen MHR 159. 2k (2019-11-29) 8.33.8@23

User avatar
Carl Watts
Half Marathon Poster
Posts: 3193
Joined: January 8th, 2010, 4:35 pm
Location: NEW ZEALAND

Re: Erratic PM3 on Model C

Post by Carl Watts » December 1st, 2019, 1:41 am

Do some searching on his forum i had this problem years ago with v108 firmware but only on certain hardware versions and using rowpro. Your pretty much stuck with it unless you go back to v105 and it will probably go away. Almost time for a new PM5 anyway its now a much better monitor with connectivity to ergdata.
Carl Watts.
Age:52 Weight: 104kg Height:183cm
Concept 2 Monitor Service Technician & indoor rower.
http://log.concept2.com/profile/863525/log

11treetops
Paddler
Posts: 4
Joined: November 28th, 2019, 1:09 pm
Location: near Stroud, UK

Re: Erratic PM3 on Model C

Post by 11treetops » December 2nd, 2019, 7:03 am

Thanks James and Carl.

James, it's definitely not mains interference.

Carl, I had already seen the v105/v108 posts and at least one person reported symptoms with v105. However, I decided to give v105 a chance after your reply but the C2 utility doesn't give access to it and I can't find it anywhere else so I will live with PM3/v108 until it becomes unusable or I feel PM5 is essential.

User avatar
Carl Watts
Half Marathon Poster
Posts: 3193
Joined: January 8th, 2010, 4:35 pm
Location: NEW ZEALAND

Re: Erratic PM3 on Model C

Post by Carl Watts » December 2nd, 2019, 2:43 pm

You need to ask C2 for the V105 file. Its also very weird how you use it by dragging that file when its on your desktop over the top of the C2 update utility. Probably also only works with the older update utility like 6.53. Maybe more hassle than its worth.
Carl Watts.
Age:52 Weight: 104kg Height:183cm
Concept 2 Monitor Service Technician & indoor rower.
http://log.concept2.com/profile/863525/log

Post Reply