Wednesday, 23 September 2015

Controlling treadmill motors by Pulse Width Modulation.

Permanent magnet DC motors used in fitness industry

Home use treadmills are equipped with DC (Direct Current) motors.  The Permanent Magnet DC Motor (PMDC) is the most commonly used type of direct current motor available producing a continuous rotational speed that can be easily controlled.

The rotational speed of a DC motor is proportional to the Voltage applied to the motor.

PWM Regulation as standard regulation for home use treadmills motors

PWM regulation on a treadmill DC motor

Pulse width modulation (PWM) speed control works by driving the motor with a series of “ON-OFF” pulses and varying the duty cycle, the fraction of time that the output voltage is “ON” compared to when it is “OFF”, of the pulses while keeping the frequency constant.

The voltage applied to the motor can be controlled by varying the width of these applied pulses and thereby varying the average DC voltage applied to the motors terminals, ie, the longer the pulse is “ON”, the faster the motor will rotate and likewise, the shorter the pulse is “ON” the slower the motor will rotate.

Advantages and disadvantages of treadmill motor regulation by PWM

The use of pulse width modulation has the advantage in that the power loss in the switching transistor is small because the transistor is either fully “ON” or fully “OFF”. As a result:
  • the switching transistor has a reduced power dissipation 
  • linear type of control which results in better speed stability
  • the motor can be rotated very slow without it stalling
The main disadvantage is that the motor is driven with high voltage pulses (about 300VDC for a network current of 230VAC, 150VDC for 110 VAC). When a reduced rotational speed is required by the application (such as walking at slow speed on the treadmill) associated with the heavy load (user weight, treadmill maintenance conditions, running belt friction factor) the motor is subjected to heavy stress and overheating. This could bring easily to electric leaks inside the motor and consequent damage to the motor itself and/or controller.

Friday, 4 September 2015

Adjusting treadmill motor position when replacing treadmill motor

When installing a replacement motor, a difference in the position of the fixing holes may be noted

In this case, you must not work on the threaded holes on the motor.

Drill the motor fixing bracket on the treadmill frame. If it's a curved bracket, it's better to do uninstall it before drilling

fix the motor in correct position, so that the belt is perfectly aligned, the motor is in good contact with the bracket and the fan doesn't touch anything in the back.

As an alternative to drilling the motor bracket, you could fix the motor with metal bands /jubilee clips (the one used in plumbing) as they are resistant enough for this.

Wednesday, 2 September 2015

Reinstalling the Rear Roller (Nautilus)

8.1   Slide the rear roller inside the belt and let it hang loose.
8.2   Install the alignment bolts through their holes in the  end cap and into the holes on the roller (see Figure 8.3).

8.3   Install the end cap onto the rear of the treadmill, making sure the alignment pins go into the holes on the ends of the side rails.
8.4  Hand tighten the adjustment bolts.
8.5   Align the walk belt so that the edges of the belt are equal distance from the side rails.
 8.6   Tighten the adjustment bolts to take the slack out of the walk belt.
8.7   Perform the belt tension and belt tracking procedures outlined before

9.    Reinstall the Treadmill Hood
9.1   Install all treadmill covers previously removed in step 1.2.
9.2  Plug the AC power cord into the treadmill, and turn on the treadmill circuit breaker switch.

Nautilus treadmill maintenance: Attaching the Deck & Reinstalling the Front Roller

6.  Attaching the running Deck

6.1  Align the deck mounting holes with the compression mounts.
6.2  Install all eight (8) deck screws and hand tighten.
6.3   Use Loctite 243 and a 10 mm socket to tighten all the screws to 15 in.lbs. (1.7Nm).


7.  Reinstalling the Front Roller

7.1  Slide the front roller inside the walking belt.
7.2   Insert the end of the roller opposite the pulley into the cut-out on the side rail (see Figure 7.1).

7.3   With your free hand, slip the motor drive belt onto the Front roller pulley and the motor flywheel.
7.4   Align front roller pulley with motor flywheel, then install the retainer plates in the grooves on the roller. Tighten all the screws on the retainer plates. (see figure 7.2).

7.5  Place Tensioner assembly onto the tensioner bracket and screw in bolt finger tight.
7.6  With a 15/16 wrench. Place on the large nut of the assembly and push forward until the adjustment knotch is even with the top knotch on the left side of the wheel and hold. (See Figure 7.3 and 7.4.)

7.7  Place a 9/16 wrench on bolt and tighten (counter clockwise).

Inspection and Cleaning + Installing new running belt (Nautilus) checking Belt direction arrow

4.    Treadmill Inspection and Cleaning

4.1  Check the compression mounts for any wear and cracking. Make sure they are tight.
4.2  Check the deck for signs of wear.
  Important: Do not apply any cleaners or petroleum products to the deck surfaces.
4.3  Inspect the motor drive belt for wear and cracking. Cracking is prevalent between the grooves on
the belt.
4.4 Vacuum the deck and inside the motor housing.

5.  Installing the New Walk Belt

5.1   Slip the new belt over the deck. Make sure the arrow on the inside surface of the walk belt points in the proper direction of belt travel (see Figure 5.1) toward the rear of the machine.

5.2   Lift the deck with the installed new walk belt and place it on the compression mounts.
5.3   Lift and slide the belt until the arrow is visible on top of the deck. Verify that it points toward the back of the treadmill.

nautilus treadmill: Removing the Walking Deck

3.1  Remove the right and left Rubber Side Extrusion exposing the Side Rail Bolts (see Figure 3.1).

3.2  Remove the right Side Rail Bolts and Side Rail exposing the Deck Bolts, then repeat for the left side (see Figure  3.2).

3.3  Remove the left side Deck Bolts, then repeat for the  right side (see Figure 3.3).

3.4  Lift and slide the Walk Deck out and replace if needed  (see Figure 3.4).

3.5 Reverse steps when re-installing the Walk Deck.

IMPORTANT:  When reattaching the Walk Deck with the Deck Bolts, apply a small amount of Loctite #243 on the threads and torque to 15 in. lbs

Replacing the Walk Belt (Nautilus) whenever the walk belt is still too loose after adjusting the tension or when the belt is worn or frayed

Perform this procedure whenever the walk belt is still too loose after adjusting the tension or when the belt is worn or frayed.


1.   Remove the Treadmill Hood
1.1  Turn the treadmill circuit breaker off, and unplug the power.
1.2  Remove the Front Trim, Right Lower Cover, Left Lower Cover, and Top Motor Covers.

2.   Remove the Rollers

2.1  Remove the left and right end caps (see Figure 2.1 and 2.2).

2.2  Carefully slide the roller out from the machine (see Figure 2.3).

2.3  Remove the Kick Plate and four (4) screws (see Figure 2.4).

2.4  Remove the Pivot Bolt on the left and right side of the Upright Weldment (see Figure 2.5).

2.5  Remove the screw from the Front Roller Retaining Bracket on the left and right side, then remove the brackets (see Figure 2.6).

2.6  Remove the Bolt and Tensioner assembly from the frame (see Figure 2.7 and 2.8).

2.7  Slide the Front Roller over to the left, then use the belt to lift and slide out the roller from the
machine (see Figure 2.9).

Adjusting belt tracking (Nautilus) whenever the treadmill belt moves to one side or the other.

Perform this procedure whenever the belt moves to one side or the other. Stay off the belt when adjusting  the tracking.

1. Start the treadmill at minimum speed and grade.
2. Increase speed to six (6) mph, and make the following adjustment:

2.1. If the belt moves to the right, turn the right adjustment bolt 1/4-turn clockwise.
2.2. If the belt moves to the left, turn the left adjustment bolt 1/4-turn clockwise.

3.  After making an initial adjustment, run the treadmill for five (5) minutes and observe how the
belt tracks. If the belt continues to move away from the center, adjust the appropriate side until
properly centered.

Adjusting Belt Tension on Nautilus Gym Treadmills

Adjust the belt tension whenever the belt slips or moves unsteadily during operation by following the
steps below:
1.  Start by loosening the two (2) adjustment bolts (see Figure 1).

2.  With the walking belt loose, place two marks 35 inches (89 cm) apart on each side of the belt
near the edge. The belt must be loose enough for you to move it from side-to-side on the front or
rear roller (see Figure 2).
3.  Turn the adjusting bolts clockwise by equal amounts until the marks are between 35-3/16 inches
and 35-5/16 inches apart. Proper tension for the walking belt is between .5%–.6%. This should
be about six full turns of each adjustment bolt from the point where the belt begins to stretch.
Important: Do not exceed 35-5/16 inches.


4.  Test the belt by running on the belt at about four (4) mph.  Hold the handrail lightly and resist the belt movement with your feet.


5.  If you feel the belt slip on the front roller, increase the tension of each adjustment bolt by 1/2 turn
and re-test. If you feel the belt slip again, check the tensioner adjustment.

Suggested maintenance for Nautilus treadmills

Daily Treadmill Maintenance

• Inspect the power cord and walking belt for wear.
• Check the position of the walking belt. Verify it is not rubbing against the frame. The belt should be
evenly spaced on the deck within 0.25 inches of each side rail. Adjust the belt if necessary.
• Check the optional side handrails to ensure they are fastened securely.
• Remove potential hazards from the treadmill area.

Cleaning Treadmill
Keeping the Nautilus ®  Commercial series T9 treadmill clean on a regular basis will help to improve
operation and increase the lifespan of the components.

•  Keep the treadmill and controller free of dust and debris. Use a damp sponge to wipe the exteriors
and walking belt; do not soak surfaces. Dry all surfaces thoroughly.

•  Elevate the treadmill to maximum incline and vacuum the floor under it to prevent excess dust and
dirt from interfering with operation.
•  If the magnetic key is being used, check it for rust. If you detect rust, replace the magnet. Rust on
the magnetic key will cause power-up problems.

Treadmill Interior

Depending upon the treadmill environment, dust and or lint can accumulate under the hood. Clean the
interior of the treadmill following the procedure below:

1. Turn the treadmill circuit breaker off, and unplug the treadmill power cord.
2. Remove the two (2) screws on the treadmill hood.
3. Lift off the hood.
4. Clean inside the unit.
5. Reinstall the hood and the two (2) screws.
6. Plug in the treadmill power cord, and switch on the treadmill circuit breaker.

Model T912 / T914 / T916 by Nautilus. Viewing Maintenance Information | Engineer mode for treadmills

Treadmill Model T912

The total time and distance the treadmill has been in use can be viewed using the Maintenance Screens.

This information can help you schedule treadmill maintenance and check treadmill usage.
To view the treadmill’s  total Run-time and total Distance information:

1. Press and hold ENTER and STOP keys on the console for at least 3 seconds.
2. Use the INCLINE UP/DOWN keys to scroll to ConF selection.
3. Press the QUICKSTART key.
4. Use the INCLINE UP/DOWN keys to scroll to view TOTAL HOURS and TOTAL MILES.
Model T914 & T916
In addition to the total time, the distance the T914 or T916 treadmill has been in use can be viewed using
the Machine Status console codes.
To view the treadmill’s run-time information:

1.  Press the SPEED UP key on Ergo Bar, then 4, ENTER on the console.
2. The words "Machine Status" will be displayed.
3. Press the SPEED UP key on Ergo Bar, and scroll to "Run Hours".
4. The current Run Hours will be displayed.
5. Press the CLEAR key to exit. 
To view the total distance the treadmill has been used:
1.  Press the SPEED UP key on Ergo Bar, then 4, ENTER on the console.
2. The words "Machine Status" will be displayed.
3. Press the SPEED UP key on Ergo Bar and scroll to "Distance".
4. The current Distance in the current machine units (Miles/KM) will be displayed.
5. Press CLEAR to exit.

Routine Maintenance Schedules
Performing routine maintenance will help prevent unnecessary wear to the treadmill and/or injury to the user. The maintenance schedules are meant only to serve as a guide. Depending on where and how the treadmill is being used, more frequent routine maintenance may be required.

Sunday, 26 July 2015

Treadmill controllers: replacing old Astek models (TD700/800/1400/1600/1600N) with new models TD300/350/1800

Main difference between the old and new range of AsTek board is that due to Erp (Energy Saving) regulations, the external transformers have been removed.

OLD CONTROLLER (TD700 REV. 1.2 REV 1.4, TD1400, TD800, …)





Sunday, 28 June 2015


I have received my order from you (a GMD118-1 GREENMASTER COMPATIBLE MOTOR)  and it has been placed according your directions.
I have verifyed the correct installation and maintenance but the motor still overheats. Do you have any other sujestions? Please note that the treadmill is used only by me (I weihgt 80kilos)
once a day and for 1 hour and I usually keep it to 6km/hr.

1) Check if the speed is OK. Sometimes speed needs to be adjusted via the SPEED trimmer on the control board. If speed is lower, that could bring overload to motor
2) Check proper lubrification of running belt. Add some (not too much) lube on the running back. Use only 100% silicon oil lube. Don't use PETROL derivates, as they damage the belt and have the opposite effect (increase friction factor of belt)
3) Check if the rollers are smooth. Try to move the belt with your hands frontward and backward, this should move smoothly. If not, cause may be too much tension on drive belt, old running belt or problems with rollers (i.e. roller pulley not aligned, roller bearings damaged)
4) Check running deck if smooth and flat. If there are grooves or hollows, this should be replaced or turned upside down
5) Test for 30 min at 12 km/h and nobody on the machine, if after the test the motor gets hot, double check the above points. If not, if the running belt is more than 4 years old, replace the running belt.

Buy compatible GMD 118 treadmill motor

Monday, 6 April 2015

in a 180Vdc treadmill motor, what is the maximum Vdc the motor will accept running?

Question  in a 180Vdc treadmill motor, what is the maximum Vdc the motor will accept running?


1) the voltage to the motor is never the maximum, the controller cuts it to regulate the motor speed.

2) there's not a standard rule about the max voltage accepted by the motor, depends on the motor curves. Anyway the motor accepts 300V for example if the controller is in short circuit you'll see the motor running with 300VDC (with no load), and it's not damaged.

3) the motor speed regulation is based on PWM, this means the voltage is 300V "cutted" such as in a cut-phase regulation. 

TM Treadmill controller


I´m trying to repair a board TM5942. I see it uses a transformer with 2 secondaries, I guess they should be around 12Vac, could you check the value of this transformer?

I also see on the connector for panel one signal is coming and another signal is going so the only way is control speed demand is coming to the board but I don´t know which signal is sending the board to the panel.

I see the processor should switch on the relay but I don´t know when because we have only one opto to send a signal from the panel to the MCB.

I see 4 LED:
LVS = ???
RLY = Relay
PANEL = Power to the panel

Can you help me to clear a little bit the philosphy under this board? Thanks, regards,


it's a tx/rx controller which speaks to the console, this is the reason why it's written connect. I don't have much experience on those TM boards as they are not very common.
If you don't have a console to test it, repair is very difficult. In this case I think it's better to give a new controller to the customer. You risk loosing time to understand how it works and then you learn just for a few pcs in your life.

when a treadmill motor is 8cm diameter, do you think it´s not possible 2 hp?

Question: when a treadmill motor is 8cm diameter, do you think it´s not possible 2 hp?


Dear Customer,

the real power of the motor depends on the motor diameter in most part and only a few for motor length.
Unfortunately, there's a big mess on the labels on the motors because some treadmill manufactures asked suppliers to write much more power than the real power.
Also most of the times it's not written if the power on the motor is peak power, continuous duty power, etc.

For this reason we must take into account the motor dimensions and not the motor label. Sometimes we remove the motor label to avoid customers asking why the label is different from their old motor.

For more details about different ways of calculating motor power, please see PDH Course E156 - Understanding Motor Nameplate Information page 19 / 20 (duty cycles + IEC class).

Which is the right replacement motor for treadmill ...

Question: Which is the right replacement motor for treadmill ... 

if you cannot find the exact replacement for a motor, you can replace with a different one, but please not the following

  1. check motor body diameter. The motor body diameter reflects the real available power of the motor much better than the (often fake) labels
  2. check the overall size of the new motor (if too big, it won't fit in the treadmill).
  3. check the voltage rating 180 up to 230 V motors should be replaced with any 180 or 230 motor. 95/110/130 V motors should be replaced with 95, 110 or 130V motor. 95/110/130V motors may also be replaced with 180V motors, but the treadmill won't reach anymore the max speed since the controller will provide max 130V to the treadmill motor.
Don't loose much time on speed rating (see also this article:  ), fixing holes position (you can drill the fixing bracket or fix the motor with metal bands as described in the blog), HP rating (this value is defined by the treadmill supplier and often is fake)

how much is the maximun tolerance we have for treadmill bands?

Question: how much is the maximun tolerance we have for bands?
treadmill walking belt replacement


usually from one edge of regulation to the other is 5/6 cm it means for the same treadmill +/- 10 cm (band).
Normally the regulation is in the middle and the tolerance is +/- 3 cm.  To select the right belt, a customer should check the end roller, sometimes the regulation is not in the middle but on one side.

Please also take a look at this explaining article

Treadmill Hera - electric diagram for inverter HERA 7000

TBR inverter  ( There is no converter )

2 HERA 7000 I 2. HERA 7000  I TREADMILL
TBR inverter  ( There is no converter )

electric diagram for treadmill inverter

N700E inverter with converter

N700E inverter with converter

electric diagram for inverter

Modification parts

1. You should make a new hole to fix new inverter and converter in the frame.
2. Open front cover and Take out power cable from front cover to inverter and put new power cable
3. Fix inverter and converter on frame
4. Connect all cables.

Wire change

1 Open front cover and separate cable from inverter and filter (for XT model) at picture 1 and 2
2 Separate cable at picture 3
3 If you separate cable at picture 1, 2, 3, you can see cable at picture 4, take it away

4 Connect new power cable and connect it to adapter and inverter

Treadmill speed regulation with endex controller

Question: you told me before, endex controllers doesn't need regulation of speed, anyway I see two trimmers on the controller.


one trimmer, Current Limit (A - MAX) regulates the max. current to the treadmill motor which impacts motor TORQUE. More current is more torque, more powerful motor, but may also bring to early damage of motor and controller if the regulation excess motor capability or if there are load problems on the treadmill.

The other trimmer regulates how the lower controller regulates the PWM (speed setting) according to the signal coming from the console. If the speed sensor is installed, this has no effect on the actual treadmill speed, because the console read the speed signal and regulates the signal to lower board accordingly. Let's say if you regulate the speed on lower controller + 10%, the console will send a signal -10% to keep the same measured speed.  

Treadmill speed: when do you need to set the speed

I´ve been reading your blog, I´ve seen sometimes you do adjustings at boards or console to set proper speed settings. When I sell a replacement motor or board I never say they have to adjust something, is it necessary. I don´t want to sell motors or boards without the proper knowledge about what I´m doing..


The setting of speed is automatic on 90% of controllers. Only a few controllers require the user to set the speed.
The most used controllers which need adjustments are:

  • Greenmaster - usually GMD market control boards, because they don't have speed sensor -> in this case, the setting is made with the trimmer speed on the lower control board.
  • Icon - brands Domyos, Proform, Weslo, Nordick Track. This controller has a speed sensor but it is used only to read speed and not to set. -> In this case there's a procedure, which you can find on the blog.
Anyway, the regulation regards to speed and it is not very important, unless for some reason the speed reported on display is much higher than the real speed.

The real issue when replacing a motor and/or a controller is that if the problem was due to lack of maintenance or other problems (such as friction of the belt, damaged motor when replacing a controller, too much user weight compared to treadmill possibility...) it will happen again.

The best would be to check with an anmeter after installation how much is the current with and without load. If the current access 1,5/1,7 A without load or 6/7A with load, it means there's some problem on the treadmill which has to be solved to avoid early breakage of replaced parts.

Newly replaced treadmill motors smells of burnt. How to solve the issue

I sold a new motor (8 cm diameter) to one customer. First he told me the motor was too hot and finally it was damaged (burnt). After that he told me he through away the complete treadmill...

Which tests and maintenance can they do on these cases? It seems the treadmill has some kind of resistence which overload the motor, isn´t it? I only can say running belt and drive belt, is any other thing which can overload the motor?


90% is a running belt problem (too much friction = belt to be replaced).
10% is too much tension on belt (drive or running), damaged (scracthed) deck (running board), damaged rollers (quite uncommon).

Basic tests for treadmills - standard current values

The ideal test is to use a multimeter connected in A-DC and check how much current consumption in different situations.
If the current consumption is high, motor becomes hot, so the problem should be evident.

I'd suggest anyway when there are problems to make sure the customer checks with amperometer how much current to the motor. The reason is that in this way it's quite precise and they can improve and see by themself the improvement.

I usually suggest to measure A-DC (direct current) with no load (for 180V motor this should be below 1,5/1,7A) and with load (for 180V motor this should be below 6/7A), then to remove tension to belt and check again (it must be lower), another test is to walk on the edges (left&right) of the belt. If there is much difference walking on the edges and in the middle, it's because the belt is more damaged in the middle -> so replace belt.

If the A w/o load is high, it worths checking with less tension on drive belt.
If the A reading seems wrong, please double check. The value should be taken on RED or BLACK cables going to motor. As the tension is regulated by PWM high frequency, some multimeters could fail in reading the values.

130V motors usually have a current consumption up to 50% higher than 180V motors.

Why lubricating is not always the final solution?

Let's say the most common problem is the running belt. Until now as a final solution I always found the replacement of the belt (except some cases with evident problems in the mechanics). Some people use lube and the situation becomes little better, but if the belt is old this effect doesn't last much, as the running belt becomes less flexible over time and this has some effect on friction and motor load.

Too smooth rollers causing excessive tension on treadmill running belt

Another mechanical issue is sometimes the roller is too smooth because of long usage. The roller must make friction on the belt, but sometimes it becomes slippery. In this case, the belt has to be tensioned much (otherwise it slips on the roller) and this brings additional load to the motor (and to the rollers bearings). Usually replacing the belts solves the problem because the new belt has better grip on the roller and less friction on the deck (because it's more flexible), while the final solution in case of slippery rollers is lathe machine.

Treadmill motors with different speed ratings

Question: what happens if a customer's motor is 4200RPM and we is replaced by a 4700RPM model?


let's say the original motor is 4200 rpm at 180 V (with  treadmill max. speed of 16km/h) and the new one is 4700 at 180v

  • if the treadmill has speed sensor the console will regulate the motor speed, so it will run at 4200 rpm at about 160/170V and 16km/h -> there's no need of any regulation on the treadmill

  • if the treadmill doesn't have speed sensor (as example Greenmaster based treadmills such as Roger Black), the treadmill will run little faster let's say 17/18 km/h. -> a speed regulation by console adjustment or SPEED trimmer adjustment on motor controller board would be advisable

Treadmill replacement motors available at Parts For Treadmill shop