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Sunday, 23 October 2016

DIY fitness machine maintenance movies

Autumn and winter is always our busiest time of year for repairs and maintenance as the increased usage and colder weather are both contributory factors to equipment failure. Therefore it is worth spending a few moments to check over your machine to make sure it is set up and lubricated correctly – a little TLC goes a long way to preventing breakdowns!


With this in mind, I have recently finished filming a series of short DIY maintenance movies to show you what to do. The movies cover all essential maintenance and how to fix common problems - you can reach the movies via the YouTube link below. In one of the movies I show you how to lubricate your machine to prevent overloading and in another I show you how to fix irritating squeaks, rattles and vibrations; I think that if your machine sounds and feels right then it follows that it should be running right as well!


Here is the link to the movies:


(It’s worth saying that if you are at all concerned about clicking through on this link then you can also access the movies via our website – just google search “Northwick Gym Repairs”).


And, if you find the movies helpful then stay up-to-date by clicking the big red “subscribe” button in the top right hand corner of our YouTube channel.

Thursday, 14 July 2016

Treadmills with 2 speed sensors

Treadmills with 2 x Speed Sensors (eg. LiveStrong/Vision)

Some treadmills are fitted with 2 x speed sensors .
One is a standard magnetic reed switch fitted near the roller pulley and the other is an optical sensor mounted at the rear of the motor. The magnetic sensor is used for general speed measurement whilst the optical sensor is used for accurate control and safety.
Faults with the optical speed sensor are often confused with MCB problems, and due to the presence of the magnetic reed switch sensor, the optical speed sensor is frequently overlooked and not tested at all.
Problems with the optical sensor can usually be cured simply by blowing dust/dirt out of the sensor lens as part of a service.

Symptom of faulty optical speed sensor
Motor runs erratically.
Running belt speeds up/down and has trouble holding a steady speed (irrespective of whether there is a person on the machine).
Motor cuts out after a while.
Motor runs momentarily but then cuts out almost straight away.

System Operation
The system uses a magnetic speed sensor to monitor the running belt speed and allows the console display (kph/mph) to be re-calibrated accurately between different models. This allows the same electronics to be shared among multiple treadmills which saves costs.
However, the magnetic sensor is relatively slow to respond which can lead to speed fluctuations (a perceptible lag while the system makes automatic adjustments to maintain a set speed). This is also why an E1 speed sensor error usually takes up to 10 seconds to appear.
The optical sensor works much faster. It allows the system to respond very quickly to speed fluctuations so as to provide a very steady belt speed. Also, it allows the system to detect a problem far sooner than the magnetic sensor and hence shut down the system rapidly in the event of a problem.
Therefore, by using the two speed sensors, the manufacturer can share electronics between different models whilst also providing a very responsive control system.  

Operation of the Optical Speed Sensor
The optical speed sensor is an electronic device consisting of an in-built LED and sensor. Light passes from the LED lens to a receiver which is mounted directly opposite. When the light beam is interrupted a signal is passed to the MCB (the sensor generates an electrical on/off signal to indicate speed). The light beam is interrupted by use of a castellated round disk mounted on the rear of the motor which passes between the light beam of the sensor which blocks or allows light to pass as it rotates.
The optical speed sensor itself has no moving parts and is inherently reliable.

Common Problems and Fixes:
Dust on Lens
By far the most common problem on treadmills is dust and dirt on the lens or receiver of the LED. This blocks the light beam and causes the sensor to give an inconsistent output or no output at all. This can be resolved by cleaning the lens with an air blast or removing the dust with a small, clean paint brush.

Wires & Connections
Optical sensors can have 3, 4 or 5 signals wires depending on the configuration. These small wires can be trapped or snagged under screws and can easily become disconnected. Check connection and wire continuity using an multimeter. Repair and damaged wires or replace device. (Wiring and pinouts vary and cannot be easily tested using a multimeter without knowing the circuit)

Physical damage
Usually a thin metal castellated disk mounted to the motor shaft is used to interrupt the light beam of the sensor. This disk is prone to being bent or damage and can rub or scuff the side of the plastic enclosure of the LED or the circuit board. This can sometimes create debris which can block the light beam or in extreme cases cause complete failure of the sensor. Clean the lens and remove any plastic debris and re-try otherwise replace the device.

Monday, 29 February 2016

E1 Error Codes

A Technical Paper Courtesy of

Checkout the online parts store at


Error Code – E1
This Error Code may appear under 3 different situations:

The “Start” button is pushed and the E1 error code is displayed immediately.
The “Start” button is pushed, the display counts for 3 seconds, the DC Motor begins to run and then stop after 6 seconds, when the E1 error code is displayed
The “Start” button is pushed, the display count for 6 seconds, and then the E1 error code appears. The belt does not move in this situation.

After you determine which of these scenarios is occurring, please follow the instructions below to correct the problem.

If the E1 error code shows immediately it is likely a wiring connection problem. Check the connector at the back of the display, in the handlebars and at the bottom of the right side support post. Make sure that the connectors are turned the right way, that none of the pins are bent and that they are firmly pressed together. If this does not sole the problem you may have a problem with a wiring harness. Check to see if the harness was damaged during assembly by visibly inspecting the harness where the handlebars and the support post are connected during assembly and where the support post is inserted into the base. If there are signs of damage, you can isolate the mid-section of wiring harness and test to see if this is the problem through removing the display from the handlebars and attaching it directly to the end of the wiring harness coming out of the right side of the base. If the display now works properly, replace the damaged wiring harness.

If this does not resolve the problem, remove the bottom hood cover and replace the wiring harness from the controller board to the base. 

If the E1 error occurs after the belt starts to move for several seconds, the error code means that the system is not picking up the speed of the motor. This pickup comes from a magnet mounted on the front roller pulley and a speed sensor, or a problem with the magnet. To resolve this problem, follow these steps:

A.     Check the connection between the speed sensor and the controller board. This connection will be sealed with hot glue to keep it from loosening. Make sure that the connection is secure without removing the hot glue.
B.      Make sure that the magnet is properly installed on the front pulley. If you cannot located the magnet on the pulley order a new magnet.

C.      Replace the magnet sensor by following the instruction found in this manual.

If the E1 error after the display count the workout time for 6 seconds but the belt never begins, the error code means that the DC Motor or circuit board  is likely defective and needs to be replaced. Although unlikely, the problem could also be associated with a defective Transformer.

In this case you should seek expert assistance (refer to to arrange a site visit or to locate your nearest service provider) 

Wednesday, 10 February 2016

New Online Store NOW OPEN!

Buy with confidence from my new online store!

Parts for Treadmills

Treadmill Spares

And much more!

International shipping on spare parts and consumables for treadmills, cross trainers, elliptical trainers, upright bikes, recumbent bikes, strength machines and spin (indoor) bikes.

Thursday, 10 December 2015

Cybex product discontinuation

Please be advised that beginning January 1, 2016, Cybex will no longer provide service support for the following products:

·         VR2

·         600A Arc Trainer

·         610A Arc Trainer (Main frame will still be supported)

·         530C Bike

·         530R Bike

Independent service providers such as will be able to provide continued support for most mechanical and electrical/electronic items for these products. However, certain bespoke items such as consoles, control keypads and frames may not be cost effective to repair or reproduce in the long term.

Monday, 30 November 2015

DC motor brush problems

Problems with DC motor brushes on Treadmills

See photos below for an interesting case study with regards to DC motors that was found by one of my Engineers.

The motor in the photos had passed our motor current test at 3.9A at 220VAC on load at 12kph, suggesting all was well. However, the machine, a European spec Sprint 9 domestic treadmill, showed an intermittent error 3 which we noticed was triggered when using one of the console programs functions which had a fast acceleration at start-up. The problem was not showing when starting the machine slowly on manual mode.

The issue is that the carbon brushes and commutator have been arcing/sparking (burning) as shown in the middle picture below. This is caused when there is a small gap between the face of the carbon brush and the commutator (the copper segmented ring on the rotor of the motor). In this case, the burnt brush in the motor gets stuck in the slideway which you can feel when you push the brush in with your finger! The brush does not freely slide in and out of the slideway. This means it has been prevented from having a good contact with the commutator, which is why it has been arcing.

By nature, arcing is transient (very short) bursts of energy. Because the spark is present for only a very short period of time, the motor does not show as faulty when measuring the current draw on the current clamp – the sparks would have to be much bigger and last for a lot longer to have an effect on the current draw of the motor. This is why it had passed our motor current test.

However, the spark does create a great deal of electrical interference which causes the MCB to shut down (intermittently) which is why we tended to get the error 3 during a rapid acceleration rather than on a slow start (the arcing would have been more during high acceleration). Our motor test box has very high immunity to electrical interference and it is not affected by the arcing which is why it did not cut out under the same circumstances.

This is a fairly rare fault but worth bearing in mind especially if you have reports of the motor intermittently cutting out – check the brushes and commutator for burning, especially if the current readings are good!

The photos show you what a good brush will look like and what a bad brush will look like and what a burnt commutator will look like.

On this job, my Engineer changed the motor for a new one which cured the problem. We decided that it was more cost effective to do this rather than strip down the motor to fix the slideway.

Good brush (shiny surface with only light burning at one edge)

Bad brush showing lots of burning (matt black deposits at surface)

View of motor showing brush and slideway

Thursday, 3 September 2015

FREE technical training at LIW 2015

Jon Isaacs aka "The Treadmill Engineer" will be at LIW in Birmingham which is the UK's premier fitness industry show. The show runs from September 22 to 23 2015 at the NEC in Birmingham, UK. Jon will be running a series of drop-in style technical training sessions to help you look after and get the most out of your equipment. more details here

For more details or to meet Jon one to one contact otherwise feel free to just turn-up and join-in.

You will find Jon at The Workout Trade Stand.

Saturday, 14 March 2015

How to professionally test a treadmill motor and MCB

These 2 movies shows you how I recommend thoroughly testing a treadmill motor and MCB. 

This is also how my Engineers at perform onsite testing.

Note that this is a DC motor system - different rules apply for an AC system!

DO NOT try this at home as you will be in direct contact with mains voltage which can kill.
ALWAYS seek expert advice and only use suitably qualified technicians 

Visit for more information

Part 1

Part 2

Monday, 8 September 2014

Recommend current limits for treadmills

Recommended Treadmill Current Limits 

(Part 2 of a 2-Part report. Click here for Part 1)

Further to my previous post, I have now completed some more work to help validate the most appropriate trigger point settings for the Treadmill Saver.

Treadmill Saver is a new product designed to alert gym operators when (a) essential treadmill preventative maintenance is required and (b) when excessive electrical current is being consumed. 

Treadmill Saver is a convenient visual indicator as to the condition of your treadmill and can save you energy and help prevent breakdowns. Of course, it will only work effectively if it is set up correctly. The purpose of this experiment is to determine the most appropriate trigger points. 


In speaking with my gym manager, our feeling is that our treadmills will on average be running at 10kph. Therefore, we chose to measure the current in the loaded and unloaded condition at 10kph on each of our treadmills. For info, I ran on the machines for the loaded test and I weigh 91kgs. For comparison, we also measured the current at maximum speed of our Life Fitness T9i treadmill with a new PowerBelt and platform (20pkh).

The results were as follows:

Technogym Excite (not new belt and deck but running well with light wear):
3.3A loaded
2.3A unloaded

Life Fitness 9100 (not new belt and deck but running well with light wear):
3.5A loaded
2.5A unloaded

Life Fitness T9i (new belt and deck and fresh application of silicone oil)
3.8a loaded
1.9a unloaded

Life Fitness T9i at maximum current draw at 20kph (top speed)
8.8a loaded*
3.9a unloaded

*Very difficult to run on for more than a about 5 seconds!


I conclude that all of our gym treadmills are running at, or close to, their optimum condition. Therefore, it would be appropriate to set the Treadmill Saver amber warning set point to be slightly higher than the optimum so as to avoid false triggers.  I would recommend a +20% current drift from optimum which would make the amber set point about 4A.

For the red set point, it would be desirable to choose a threshold which is somewhat higher than the amber set point but not so high as to allow the machine to operate continuously outside of its maximum operating parameters. Based on the current draw at top speed of the Life Fitness T9i, the maximum current draw (maximum speed in the loaded condition) is 8.8A. However, we found that it is not possible to run at 20kph for more than about 5 seconds. Therefore, it is reasonable to suppose that the design criteria used for treadmills is actually based around a continuous current (speed) rating rather than a peak current (speed) rating and so I suggest 6A is a realistic set point for red.

Therefore, I would recommend an amber (maintenance overdue) set point of 4A continuous and a red (stop using) set point of 6A continuous. 

The Treadmill Engineer
If you would like more details about this post, please contact me

Treadmill running belt - PowerBelt

PowerBelt Treadmill Running Belt Reduces Energy Consumption by up to 75%

(Part 1 of a 2-Part report - click here for Part 2)

I have some data regarding the current consumption measurements that I made after fitting a new PowerBelt running belt recently supplied for our Life Fitness T9i treadmill at my own gym in Worcester.

For this test, I measured the “before” and “after” amps using a true RMS (AC) current clamp hooked up to a Treadmill Saver current loop. The results below are what I found at a 5kph steady walking pace.

For clarity, the terms "unloaded" and "loaded" below simply refer to whether the treadmill was being walked on or not when the measurement was taken.

Finally, for the true Engineers out there, I weigh 91kgs (200lbs) and the treadmills are all European spec 220V AC 50Hz. 
Before belt & platform change:

1.3amps unloaded walking pace
2.7amps loaded walking pace.
Note – upon removal, the original belt and platform were found to be in good condition and plenty of residual silicone oil was in evidence.

After fitting new belt and new platform and fresh application of silicone oil lube:

Unloaded 1.3amps walking pace
Loaded 2.1amps walking pace


It has to be said, that the baseline current measured here in the “before” condition was very favourable (low) to start with and would not normally have warranted a new belt or platform being fitted. This reflects the high standard to which we maintain our own gym equipment. For comparison, in my experience, I have measured baseline current draw at 6A to 8A in the “loaded” condition in facilities where there has been little or no treadmill maintenance. In these situations, a PowerBelt and preventative maintenance routine could reduce energy consumption by as much as 75% based on these figures.

I can conclude that by using a new treadmill belt combined with a new platform resulted in a significant and measurable reduction in current draw.  Even under these rather favourable conditions I was able to measure -0.6A (-23%) less current after the new PowerBelt and platform had been fitted.

Besides the obvious savings in electricity running costs, in my opinion, reducing the current  will also have a long term positive effect in helping avoid failures of expensive components such as the motor and drive circuit board; the lower current consumption means these items will run cooler for longer and will ensure they operate well within their design parameters (so no stresses to bring about premature failure!).

Next Steps:

The current monitoring capabilities of the Treadmill Saver provides a convenient way to alert the user when belt maintenance is required and, now that we have optimum conditions here with the new belt and platform fitted, I will conduct some further work to establish where we should be setting the trigger points for the amber (maintenance overdue) and red (stop using) warning.

The Treadmill Engineer - August 2014
For more details about this test, please contact me