Hi all,

Great forum, joined to say Hi but been visiting a while.
Wondering if anyone can help with an issue with my Treadmill.

I have a Horizon Quantum II HRC Treadmill which has the following fault:
When pressing the START button, the motor and belt runs at full speed. The LED speed shows the default 0.5mph, but as I said the actual speed in FULL speed.
If I adjust the speed using the speed buttons, the LED shows the increase/decrease in speed but it has not affect on the actual belt and motor which are running at FULL SPEED.

The incline buttons work fine, and also the STOP and START buttons.

So issue is, soon as START is pressed, it runs at Full speed.

I'm no good with electronics (when it comes to circuit boards) but always willing to have a go.

I've taken the MCB (Motor Control Board out) which is part number 013675-EH (according to Horizon support). But the price of a new board is more than £190+

I've done a visual check of the board and there doesn't appear to be any burnt components, but other than that I haven't a clue.

Could anyone be so kind as to help me diagnose the issue?

Many thanks,
Sharpy

 

Sounds to me a bit like the tach method is not working?
Usually a slotted disk and slot Opto sensor.
Max.

 

Hi Max,

Thanks for your reply, but I am not electronically minded, so didn;t understand a single thing you said.
Any chance of that in laymans terms?

 

The controller usually uses a tachometer on the back of the motor to control and monitor the rpm, this is commonly in the form of a slotted steel disc on the rear of the motor.
It uses an optical sensor/interupter type of device to detect the rate slots as they turn past the sensor.
If this is shot, then the board thinks the motor is not turning and it needs to ever increase the speed.
Max.

 

Thanks for the explanation.

Not even looked at the motor, as I assumed the Motor Control Board was the culprit.
I'll have a look at the Motor to see if I can see this slotted steel disc you mention and report back tomorrow.

Appreciate the help,
Sharpy

 

Hi max,

Can't see any steel discs. I've uploaded pics of the motor. There are two plastic slots (one on front and one back of the motor - see pics) but can't see any steel discs.

There is a speed sensor on the side of the treadmill near the belt is that the other place it could be if not on the back?

 

It could be located on another point, the motor is the common one, also if internal to the motor, there is usually more than two wires entering the motor.
Can you post the belt sensor.
Max.

 

Hi,
Here is a pic of where the sensor is located.
Also is a schematic of how the mcb and motor are connected.
This is a link to the parts diagram: http://www.fitnessrepairparts.com/diagram/7264

As you can see, done loads of research, just can't work out the actual fault though

 

That shows a reed switch and magnet operator, reed switches, being mechanical are prone to a short life, it should be easy to test by unplugging and place a ohm meter across the contacts and use a magnet to see if it opens/closes.
Max.

 

Hi Max,

I've been out to test the Sensor as you mentioned. With a Voltmeter set it to ohms, tested it without being near a magnet and it displays nothing. Soon as I put it near the wheel (where there is a magnet) the reading went to 01.0 ohms. So it seems the sensor is ok.

What now?

 

Other than that next it could be the motor controller FET's or SCR's, dependant on how it is controlled, it would really need a board schematic to take it much further.
Can you post a Pic of the main board?
Max.

 

Hi,

MCB pics included: This is a double board, the top board plugs into a secondary board as you can see from the pics:

I've looked everywhere on the internet for the schematics for the board but cannot locate them. What I can tell is that the following info is printed on the board:
JHT.co
2003.04.02
PCB230D002F
220V
2.0 HP

If you need a pic of the under-board, let me know.

Again, cheers for the guidance so far...

 

The prime suspects would be the 3 components on the heat sink in the 2nd pic bottom left.
If possible read the part numbers.
Max.

 

Sorry not sure which 3 components you mean? The heat sink at bottom left has D13 and D14 just above it.

 

Unscrewed the top board. There are 4 components screwed to the heatsink:

from left to right they are marked as follows:

1. IRFP360 ir503L 8A
2. MOSPEC U15 A60
3. S6025L A5
4. Sun-B MP35108

Two more pics, top board and bottom board

 

You should check them all for any kind of short circuit or very low resistance, measured in both directions, problem is they are best checked out of circuit.
Max.

 

Hi all,

Still no joy fixing this. Is there anyone in the UK on here who would be willing to have a look at it for me?