Treadmill switches off when set speed exceeds 2km/hr

[Frank747]

My treadmill (INFINITI M100) stopped suddenly while running on it at 10 km/hr. The console display then showed E1 error. There were no blown fuses or any other apparent mechanical problems. I decided to start the machine again without walking on the belt. It started as normal at the lowest speed of 1km/hr and continued working until the speed on the console was increased just past 2 km/hr, at which point it stopped and error E1 was displayed. I then did some testing as follows:

a) I slackened the belt to ensure that belt friction wasn't causing the problem, but the same thing happened- the machine starts as normal at low speed but when speed increases past 2km/hr, it stops and displays E1 Error.

b) I have installed a new speed sensor but this made no difference.

c) The motor is a DC motor – 1.5 HP, 180 V, 7.5 A. Test results/observations:

- resistance of the armature winding is approximately 2 ohms. This value changes as I rotate the motor shaft.

- resistance between the winding and the case of the motor is infinite. Repeated this test while rotating the motor shaft by hand. Again infinite ohms.

- attached a 9V battery to the winding terminals and the motor turns at low speed as you would expect.

- I shorted the winding terminals and rotated the motor shaft by hand. I noticed only a slight increase in force required to turn the shaft with the terminals shorted as opposed to the terminals open circuit. Is this the way it should be

d) The motor control board is an ASTAR TD 700 v1.2. Observations:

- when machine runs at 1 km/hr, LED 5 (LED in Speed circuit) blinks steadily at relatively slow speed.

- when the speed of the treadmill is increased to 2 km/hr, the LED starts flashing faster and faster and a few seconds later it lights up solid and then the machine turns itself off and error E1 is again displayed on the console.

I suspect that the problem may be with the control board. The motor seems to pass all tests (not sure about the last one above). I would appreciate any help I can get to solve this problem please.

 

[Minder]

What is the number on the main board?
Motor braking with the leads shorted and spun is normal for a P.M. D.C. motor
It is usually easier to run and trouble shoot the board separately on the bench, but in some cases needs a small PWM drive board to do it.
M..

 

[Frank747]

Thank you for the reply, Minder.
The number on the board is TD-700 v1.2. I have attached a photograph here. The circuit diagram of this board has been published in the thread "Treadmill controller varistor blown".

Regarding the motor, I read on another post that when the motor windings are shorted and the motor shaft is spun by hand, it should be very hard to spin. This is not so in my case. Is this important? Could the motor be faulty even though it passes the other tests?

 

[Minder]

Normally with a P.M. field, D.C.motor, shorting the two leads and giving a good spin would result in definate resistance to spinning it.
Another test is to back feed it and the motor should generate a DC voltage, directly proportional to the RPM and the rated voltage at max rpm.
A automotive battery is also a good test.
Unfortunately I have nothing on that make of board.
M.

 

[Frank747]

The MCB shown above has two power resistors at the back labeled Astar A and Astar B (please see attached photo). No indication of Ohms value. A is connected between M+ and the cathode of Q2 (FEP30JP). B is connected between the cathode of Q2 and the emitter of Q1 (GT60M303). I have tested them and they seem to have zero or near zero resistance. What should their value be? Anyone out there that can help please?