Vdd drops to ~.3V when PM2 turns on

Maintenance, accessories, operation. Anything to do with making your erg work.
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Vdd drops to ~.3V when PM2 turns on

Post by jnieman21 » April 21st, 2024, 5:16 pm

Hi Folks, thanks for the help.

I have a PM2 unit that won't show the display (it used to briefly, then would turn off, and now it won't turn on at all). I'm tracing back from the MAX1044, and I found that when the device is off, V+ (pin8) gets a solid 3.0V, but when I press the unit's "on" button, pin 8 drops to about .3V, then slowly creeps down from there.

I wasn't sure what that connected to, so I traced it back and found that it's tied to Vdd (pin 5) on the main PCF8576C chip as well... not great.

The slowly decreasing voltage leads me to think bad cap somewhere, but 🤷‍♂️

Any ideas?


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Re: Vdd drops to ~.3V when PM2 turns on

Post by Citroen » April 22nd, 2024, 2:21 am

If you're in the United States then replace your PM2 with a brand new PM5 retrofit kit and row away happy.

There is no value left in PM2 / PM2+ monitors and the PM5 is very cheap in the US.

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Carl Watts
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Re: Vdd drops to ~.3V when PM2 turns on

Post by Carl Watts » April 22nd, 2024, 5:44 am

They are not that hard to repair with a bit of electronics knowledge and if you have the skills to change a couple of parts.

The LCD Driver will not be the problem.

PM me and I can send you my e-mail address.

Its worth fixing if the board is clean and corrosion free or else it will take more time than its worth to fix and you are better off with a new monitor.
Carl Watts.
Age:56 Weight: 108kg Height:183cm
Concept 2 Monitor Service Technician & indoor rower.

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