PM2 monitor (display intermittently working)

[2tx]

Rev 1.7
Enhanced PM II
Ser # 01/03/96

No sign of corusion.

Display are dark most of the time, seems difficult to get it to work with on/off buttom.
Need to row to get it started, ore replace batteries...

Sometimes, the display are very dim, before it fade out after few second. (Replacing batteries)
Seems to be a littel bit heat related.
When in turns on, it stays on...

Have + 3.2 volt @ C10 and -3.2 volt @ C11

Have seen E007 and E008 a few times.
The reset sequense it not working the according to manual.

Thanks for any input!

[Citroen]

http://www.c2forum.com/viewtopic.php?f=10&t=12131

[2tx]

http://www.c2forum.com/viewtopic.php?f=10&t=12131

Thanks, but this is not the problem as Carl Watts write in this post:

Personally I have serviced dozens of these and the contact between the Elasopolymer strip and the LCD has never been a cause of the problem.

LCD and elasopolymer strip are cleaned.

But I get like 3 mA current, dropping to 0,1 mA after few second most of the time, when I insert the batteries.

[2tx]

Update:

Connected a spare RPM pick up sensor.
When I touch this sensor with a magnet, the display works every time, pulling 2.64 mA, dropping to 0.1 mA,
when it goes in to stand bye mode.

The monitor would not start every time when connected to the pick up sensor on the rower.
This sensor works ok with the PM4.

But the buttons are not working most of the time, very hard to do a reset...
Have not been abel to do the full reset...

Have seen 0 in the bottom left corner.
Counting down from 255 in the top left squere.
Got 5 in the middel squere.

But forgot to push on/off again

Any other way to force a reset?

When forced to start the display, it's working on the rower, inclusive hart rate receiver, 3.17 mA with HR receiver.

[Carl Watts]

Clean the rubber carbon part of the button with IPA and a cotton bud and also clean the carbon board contacts with the same. This will restore the button to working condition.

If it is a heat related problem the MAX1044 or LT1044 that generates the -3Vdc has gone and you would find that this was dropping out as the screen fades. This part is the 2nd most problematic semiconductor component on the board. I would say you have others problems as well with the copper tracks on the board to give you the E008 and the E007 may or may not clear and will keep coming back to haunt you even after a reset as it's the 1st most problematic semi on the board thats causing it.

You will need to have reasonable soldering equipment and skills with SMD rework to fix it or know someone who can do it for you.

Realistically the Rev 1.7 was one of the earlier PM2's and I would now be looking at getting a PM3 if you do alot of rowing. It is a far better monitor now and you wouldn't go back after using one.

[2tx]

Carl,

Thanks for putting me in the right direction.

The MAX1044 is changed.

The keypad was cleaned from before, but I recleaned it and got all the keys working except from the on/off.
Figured out that the on/off buttom had very high resistans, "shorted the bord with" 200 ohm resistor, and the on/off is working.
Made a quick fix, changed the carbon layer on the keypad.

Did a reset and every thing seems to be working so fare.

I got a PM4, but nice to have this old PM2 working...

[rower]

Hi, I need some help!

PM2 monitor is failing.

No corrosion on PC board, switches on and switches between functions.

Plug sensor plug in and the display still works.

Start rowing and the monitor stays at zero. Same if function is switched to timer. The time is shown, start rowing and the timer stays at the pre-set time.

Sensor appears (visually) okay.

Connection cale okay.

Any ideas if it can be fixed please?

Frustrated Rower

[2tx]

Do you got a multimeter?
Messure the resistans in the sensor,
Should be around 106-109 ohm.

It might be an open loop in the wire,
try to wiggel the wire from the plug and onwards...

[rower]

Hi, Yes, measured resistance is approx. 120 Ohm across the input plug for the monitor.

[2tx]

Are the sensor able to switch on the monitor, when you start rowing?

The easyest would be to take your monitor to another rower and plug it in and test.

It's not easy to measure whit a multimeter, but the sensor is generating about 6 uA when the magnet on the fan is passing
the sensor. Row slowly and messure when RPM is going down.

If you touch the sensor with a magnet it would generate about 0,9 mA. (I used a flashlight magnet).
You can also test if the touch with a magnet would switch on the monitor.

[Carl Watts]

You need an oscilloscope to look at the signal from the sensor, its just millivolts in amplitude when the magnet passes the sensor which is just a coil of wire.

If you wiggle the sensor plug while measuring the resistance and it is about 106 Ohms then there is no problem with it.

I have had a couple of PM2's that have developed a problem with the input amplifier and it has got weak. If you have a magnet and a sensor then if you wave the magnet as far away as 1" or 25mm from the surface of the sensor then the PM2 should turn on. If you have to go closer than this then there is a problem with the PM2.