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Craig
Craig, Electrical/ Electronic Technician
Category: Consumer Electronics
Satisfied Customers: 4529
Experience:  33 years troubleshooting electronic and electrical control systems for all types of equipment.
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I have a 6 year old Sears Pro-form 765 EKG Treadmill, Model#

Customer Question

I have a 6 year old Sears Pro-form 765 EKG Treadmill, Model#NNN-NN-NNNNthat probably has a grand total of 100 miles on it. This morning everything seems to work fine except the speed. I cannot make it go any faster than 3.0 miles per hour. I have done everything having to do with the belt adjustment and checking to see that all of the LED's are lite or flickering properly. All checks out. There is nothing rubbing against the belt and the interior small belt that turns the motor seems brand new with a fairly tight tension. I have tried to adjust that belt both ways.....a little looser and a little tighter. The treadmill runs at the full 10.0 miles per hour with no one on. If I get on, it will still show 10.0 mph, but will be actually running about the 3.0 to 3.5 mph???

Can you help??

Dave
Submitted: 5 years ago.
Category: Consumer Electronics
Expert:  Craig replied 5 years ago.
Have you done a 'calibrate' procedure on it? This is important to do so that the speed signal is correct for the speed you are asking for. Use the manual and recalibrate.
Customer: replied 5 years ago.
Yes, I did the calibration several times. However, only with the speed which was the Level 2. Still no difference in the speed.
Expert:  Craig replied 5 years ago.
  1. Set the speed to 2.5 MPH. Let the treadmill run without anyone on the belt. Check to see if the speed is constant or if there is a variation.
  2. If there is no variation, step on the belt. If the speed slows down or speeds up, you may have an output problem on the DC board. This is the board that connects directly to the motor.
  3. Communications test- Look on the board for a flashing signal as you increase speed on the treadmill. Most boards have a signal feedback test light. If a LED flashes, your communication is ok.
  4. Feedback test- If your unit is equipped with an optical feedback (disk inside a sensor) you can swap the feedback unit with the incline (it is the same part on many Icon machines). If it tests ok, you don’t have a problem here. If it is a magnetic feedback unit, you can test continuity with a multi meter or replace with a new part to test. Many times passing a kitchen magnet in front of the signal will make a speed display on the console if the magnetic sensor is good.


Edited by Craig on 11/11/2009 at 7:46 PM EST
Customer: replied 5 years ago.

There is no flashing light on the display board when increasing speed. Only the numbers go up. Also, no flashing light on the circuit boards when increasing the speed. Just the steady Leds and the flickering LCDs remain the same.

 

As for your #2 question/answer, this is beyond my expertise. Have no idea as to how to do what you say needs to be done........sorry!

 

Dave

Expert:  Craig replied 5 years ago.
If the LED does not flash when you call for increase in speed, the speed signal is not coming into the board. This may indicate a bad 'speed pot' or board failure.
Customer: replied 5 years ago.

Okay, I started it to run at 2.5 mph. Per your instruction, I steped on board. The belt and motor slowed slightly then returned to the original speed and sound.

 

As for your #2. To interchange the incline with the speed..........does this mean to pull out a particular part on the Power Board and switch with another?? If so, how will I know which one to switch??

 

Dave

Expert:  Craig replied 5 years ago.
That indicates that the drive, the motor and motor controller are responding normally. The problem is either the speed signal or the board it goes to not responding to your speed signal increase. With out being there and testing it with a meter, that's the best I can do for you in this context.

Edited by Craig on 11/11/2009 at 8:14 PM EST
Customer: replied 5 years ago.

A possible Board failure! The Voltage Diagram that was taped inside the motor housing indicates how to check all of the lite and flickering LEDS. I have checked them all and all are working as prescribed. One of the things I may not have mentioned was, when I run the speed up to the max of 10mph, it goes right up there. However, once I am on board and try to run it up to the 10mph it will show on the board that I have set it that way, but it never got any faster than about 30 mph.

 

"IF" this is a board failure, do I have to call someone out to fix it?

 

Dave

Expert:  Craig replied 5 years ago.
In an earlier post we discussed the LED's and you said they did not flash. Did you mean in the last post "higher that 3' you said 30??






Edited by Craig on 11/11/2009 at 8:32 PM EST
Customer: replied 5 years ago.

No, I meant there was no indicator light flashing on the panel next to or near the speed indicator when increasing the speed. The numbers just went up as I pushed the speed increase button. The lights on the lower Power Panel all continued to work as they were supposed to.

 

Dave

Expert:  Craig replied 5 years ago.
So to be correct here, it actually does slow to 3 MPH when you step on? It shows 3 MPH too?
Customer: replied 5 years ago.

Okay, I think I know what you're saying. When running the treadmill at 2.5 mph and then stepping onto the tread, I hear the sound of the motor slow slightly and feel a definite slightly slower speed. This is just for a few seconds and the sound of the motor resumes a little higher pitch and the speed resumes it's 3 mph speed. The actual numbers on the MPH screen remained at 3 mph the entire time...............Hope that helps?

 

Dave

Expert:  Craig replied 5 years ago.
So that sounds normal. BUT at this point, with you on the machine it will not speed up, right? If you are OFF the machine, it will speed up to 10 MPH?
Customer: replied 5 years ago.
Yes, that is correct.
Expert:  Craig replied 5 years ago.
Ok, good. I think we're on the same page. Questions: How old is the belt? Have you lubed the deck? Are you sure it's not 'over tightened'? Do you think you could look at the motor brushes?
Customer: replied 5 years ago.

The belt is almost 8 years old. Probably no more than 100 miles logged since purchased in 2002. I have not lubed the deck as the Manual says no need to nor were there any instructions as to do so and how to do so.

 

Instructions say to tighten the belt so that you have 3 to 4 inches of play when lifting the tread. I did that and when stepping on the tread, it sliped. The directions walked me through a quarter turn with an Allen Wrench on each side until the slipping stopped. I did this and it no longer slips. However, the space when lifting the tread up now only gives me a 2 to 2 and a half inch lift and not the 3 to inch like the Manual says.

 

As for looking at the brushes. Another one of those things I have never done. Looks like it might take a while to take all apart and would leave that to a house call if needed.

 

Dave

Expert:  Craig replied 5 years ago.
One more quwstion: When it's running at 10 mph AND YOU GET ON AND IT, THE BELT SLOWS TO 3 mph. DOES THE SPEED STILL SHOW IT'S RUNNING AT 10 MPH??
Customer: replied 5 years ago.
Yes. The numbers dialed in never changes. Nor do the minutes or anything else. Everything stays set the way I entered it. The only thing that changes is the slower speed once I step on. I am only estimating that the speed reduces down to the 3 mph as I can walk it, while the 10 mph is a run.
Expert:  Craig replied 5 years ago.
This is sounding more and more like the console board. The speed signal is not changing or the time. What does the speed read when it's stopped?
Many times passing a kitchen magnet in front of the signal will make a speed display on the console if the magnetic sensor is good.


Edited by Craig on 11/11/2009 at 9:13 PM EST
Customer: replied 5 years ago.
Running at the 2.5 mph with me on board, I hit the stop button and the speed numbers go to zero.
Expert:  Craig replied 5 years ago.
But it said you were running at 10 MPH right?
Customer: replied 5 years ago.
yes.
Expert:  Craig replied 5 years ago.
This is a bad speed sensor. That's got to be it! We need a new speed sensor!
Customer: replied 5 years ago.
Is this something I can order and replace myself? Or, should I have a service tech come out and do it?
Expert:  Craig replied 5 years ago.
Take a look at it, it's on the drive pulley near the motor. Maybe you will even see something wrong. It's fairly small and has a small cable coming from it, and will positioned right at the pulley wheel. The pulley has two magnets on it that pass in front of the sensor head and it should be 1/8" away. You could do this yourself.

Edited by Craig on 11/11/2009 at 9:29 PM EST
Customer: replied 5 years ago.

You know, I did check that. The manual says this sensor should be about a quarter of an inch from the pully wheel. It looked a little closer so I moved it slightly out. Did no good. Gee, what a mess, huh?

 

Maybe I should disconnect the sensor and see what it does? Then maybe I'll know?

Expert:  Craig replied 5 years ago.
Put the sensor at 1/8" away, that could be some of the probelm, or all...
Craig, Electrical/ Electronic Technician
Satisfied Customers: 4529
Experience: 33 years troubleshooting electronic and electrical control systems for all types of equipment.
Craig and 8 other Consumer Electronics Specialists are ready to help you
Customer: replied 5 years ago.

Well, I did like you said and it has definitely increased the speed. Now, at 6 mph I have to walk as fast as I can. I use to have to jog at 6 mph. So, this definitely increased the speed. I can live with this. I no longer care to run anyway. But, still need to walf fast. The 6 mph I am getting is about equal to my 4 mph that I use to have.

 

Thanks.

Expert:  Craig replied 5 years ago.
Could you accept and maybe give me a litte positive feedback for the extra effort Dave? I sure appreciate it!
Expert:  Craig replied 5 years ago.
Any chance of the positive feedback when you get a moment? Tongue out Thanks Dave, have a good one......Craig
Customer: replied 5 years ago.

Hey Craig, Yes, I would love to enter some positive feedback, but cannot locate the place to do so?? You were great and helped me patiently for almost 2 hours. We never solved the problem completely, however, did solve part of the problem which I was happy enough with. Great job, Craig..........and Thanks.

 

Dave

Customer: replied 5 years ago.

Craig, also, I DID hit the Accept Button, but never saw a payment from my VISA. I'll keep checking my VISA account. If no payment was ever sent, please let me know and I'll try a re-send. I also tried to find a place on the web site that would allow me to pay you a little more, but could not find anything. A really hard web site to follow. Poorly put together.

 

Customer/p>
Expert:  Craig replied 5 years ago.
Thank you so much, I really did enjoy working with you. So many times I find my interaction with folks a bit disappointing. It was refreshing to feel appreciated and know I helped you! Craig

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Craig
Craig
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33 years troubleshooting electronic and electrical control systems for all types of equipment.