Jinma 284 Tach died

[TimberFarm]

Where did you get the part from?
My tach died quite a while ago.

 

[piper184]

Circle G. They have both sizes in stock.

 

[Bob Rooks]

I have a NOS meter you can have to use as a tach readout.

Panel Meter - 1/8 DIN, Temperature, Process | Omega Engineering

DP20 universal panel meter with high performance & Output Options: 1/2 Relay, Analog 4 to 20 mA Isolated Output, Modbus RTU Isolated Serial Output .

www.omega.com

Also,

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www.amazon.com

 

[piper184]

Thanks Bob,

From what I can tell the DP20 only reads Hz up to 100. If I used a 60 tooth trigger (one pulse per second @ 1 RPM) it would display as a direct RPM number but would only work up to 100 RPM.

Any trigger tooth count other than 60 would require a conversion factor to RPM, which I didn't see in the manual. Easy enough to make a wall chart for reference...

I'm pretty sure the Jinma reluctor puts out a pretty steady voltage and the tach is calculating off of the frequency and would be accurate only for a ring gear with the same number of teeth. Did I miss something?

When I get time I will look at the Murphy site to see what kinds of displays they have.

Thanks for all the info.

 

[Bob Rooks]

Sorry. What I have is these:
KEP m/n MRHA3M

Red Lion m/n APLVA

Actually, I don't think these would work either, but let me know if you have a use for them.

 

[141Flyer]

Good news, bad news, more good news, more bad news.

Sensor arrived a day earlier than expected and I had time to fiddle with it this afternoon.

I ordered an 18mm sensor when I should have ordered the 15.5 (16) mm one. I didn't see that option when I ordered the first one. Went at the search from a different direction and DANG, there it was. Dumb ass parts guy in the mirror....

Checked the new sensor and like the old, no continuity at the terminals, But I had a drill motor laying on the bench and happened to notice it had a series of nice little grooves cut in the side of the chuck for easy grip. Looked like teeth to me. Flipped the multi-meter to A/C volts and spun up the chuck. As I moved the sensor tip close to the chuck I could see voltage on the meter. Checked the old sensor same way, Nothing. Pretty much confirms I need a new sensor.

Went back online to order the correct part and got all the way through checkout and my browser froze. I had just updated it earlier today. Backed out and tried again, same thing. Called the nice guy at the parts counter and explained the situation. He checked and there were no orders processed but he took care of it over the phone and I should have the correct parts in a few days.

Sheesh!

I have a 2010 JM284. The tachometer recently stopped working. This tractor has the cluster instrument panel. The hour meter is integral to the tachometer. All the instruments powered up including the hour meter. So I concluded that either the tachometer sensor unit had failed or the associated wiring/connector had an open circuit. I contacted the dealer who stated the sensor was a common fail item and that there really wasn’t a way to bench check it to confirm a failure. With shipping, a new sensor would be about $45.00. Not a big deal but I figured there had to be a way to determine whether the sensor had failed before spending the money. Then I came across Piper184’s little trick with the drill chuck. Brilliant! On the work bench I connected a DVM to the sensor wires, spun up the drill, and moved the sensor to close proximity of the chuck. I got a voltage reading but it was variable and intermittent. So the sensor was faulty and would need to be replaced. I noted that the wires enter the sensor through a soft rubber cap or plug that fits the end of the sensor unit. Out of curiosity I pried back the plug and discovered the insulation on both wires at the same location had cracked exposing the internal conductors (see photo). I separated the exposed wires so they couldn’t short and repeated the drill trick. This time a steady consistent voltage reading. I wasn’t sure how I was going to repair the wiring because of where the break in insulation was located. I ended up using RTV silicone gasket maker (it’s what I had on hand) to fill the hollow end of the sensor and built up enough silicone to encapsulate the exposed wires and immobilize them (see photo). I allowed 24hrs cure time and reinstalled the sensor. The tach works perfectly.

 

[TimberFarm]

Thanks for that tip.
I will have to look into that. Right now I am trying to fix my leaking PS line and gear box.