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Old 09-06-2008, 12:10 PM
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gerichardson gerichardson is offline
Motorized Bicycle Newbie
Join Date: Jul 2008
Location: Salisbury, MD
Posts: 9
Default Re: Hour meter on Chinese engine?

I tried one that is similar to the Tiny Tach. It worked but I had some problems.

The one I tried is an ENMCO PT15E26. There is a problem with the inductive tachometer / hours meter. I purchased two and the first installation worked great for awhile, but it would go crazy at high rpm, such as over 6,000rpm.

Sometimes it would go blank and then restart or else I would get a message “SERVICE”. It would happen randomly. These are sealed units and there are no buttons to reset unlike some. The problem may be due to RF generation from the AC voltage of the magneto, inducing current in the leads.

Initially I replaced the first unit thinking it was defective but the same problem occurred. Then after a fast ride the entire screen went blank and would not show hours. I reconnected the first one and tried to route the wires away from the sparkplug wire and CDI but it also failed the same way.
I don't have any problem with my bicycle speedo/computer it works fine.

What did I do next? What any good MB'er would do.... I dissected the unit to see if I could fix it.

The epoxy inside the back of the unit was soft and pliable and easily removed with an exacto knife and toothpick to expose the battery. The battery was a standard 3volt lithium 2032.

On the circuit board were two pads that said reset. So I shorted across them and the display performed some sort of count down with the hours symbol, the words CHG, RPM and SERVICE illuminated it looked like random numbers changing. Then it went to the display with the hours symbol and 0.0. I thought that did the trick but after a few seconds the screen went blank.

Not knowing if it was low battery voltage, I soldered on a connection to a AAA battery pack and connected a couple good batteries so that I knew there was 3 volts. This ended in the same result.

Maybe something is damaged in a chip where it listens for spark pulse? Anyone else have any ideas?

Attached Images
File Type: jpg enmcotachpt15b.jpg (8.1 KB, 106 views)
File Type: jpg enmcotach2.JPG (47.9 KB, 99 views)
File Type: jpg enmcotach5.JPG (85.0 KB, 199 views)
File Type: jpg enmcotach92.JPG (57.7 KB, 138 views)
File Type: jpg tachometer.JPG (221.2 KB, 260 views)
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