I have a Nordic Track T18 treadmill, after working quite happily for a number of years suddenly it blew my circuit breaker when I pressed the start button. I replaced the motor, motor control board and the filter and it worked for 7 minutes then blew the circuit again, now it just blows the circuit if I press start (the display lights up happily prior to this). After some head scratching I got a "specialist" out who also did a lot of headscatching, both the old and new motor seem to be fine, however there was a slight earth leakage in the incline motor under the treadmill engineers advice, I replaced this. I did however bypass the incline motor to see if this was the problem and the circuit still blew :-(
Both the old and the new Motor Control Board are correctly regulating the power to the control panel/display however they are both kicking out 280v dc to the motor, then it slowly drops to about 50v and then seems to reset and shoot back up to 280v. The motor can't cope with this power so it's tripping the circuit.
To me it would seem I need a new MCB however I'm a little confused that both the old and the new MCB are showing the same reading although the treadmill engineer suggested that the faulty incline motor could have caused this damage??
I'm at a loss now as to whether to a) send the MCB off to be tested, b) buy a new MCB at approx 100 or c) cut my losses, stop throwing money and time at the machine and buy a new one so I can start getting fit again !
Any advice would be much much appreciated ..... please

 

Place a lamp on the motor out to test without tripping the breaker.
If the motor output is ramping up it sounds like it is the Op panel, but if you have changed the operator panel, then that sort of eliminates that.?
What do you mean by by-pass the incline motor? You could just disconnect it to see if the breaker holds in.
Max.

 

I mean when the incline motor was disconnected it still blew the breaker. If I disconnect the drive motor it doesn't blow however when DC output is measure from the MCB it is showing as 280v DC and the drive motor is a max of 130V DC. When the drive motor is disconnected the incline motor works fine without blowing the breaking. Is it possible that as the old incline motor was showing earth leakage that this could have damaged both the old and the new control board. This is what the treadmill engineer suggested but I didn't have much confidence in him as he spent 7 hours here and I seemed to do more troubleshooting than he did.

 

Is there a part No on the motor control board, can you post a pic of it?
Is it a MC2100?
Max.

 

If it is a MC-2100 IIRC there is a tach signal from the motor, if this is missing, it could account for the problem with new boards fitted.
Max.

 

If it is a MC-2100 IIRC there is a tach signal from the motor, if this is missing, it could account for the problem with new boards fitted.
Max.

Hi Max
It is an MC2100, I have attached photo. Thanks for your help.

 

Here is one pdf on the MC2100, they do mention a tach signal, green wire.
This mainly outlines running the board for a different application but there is some useful info there.
Loss of tach usually results in a run away condition.
Max.

 

Thanks Max, I'm getting a bit lost so think I might have to send the board off to be tested :-( The information you sent was very useful though and interesting reading, it does tell me that the mcb is giving out too much power.

 

Did you confirm as to whether the motor has a tach wheel on the rear?.
Max.

 

Did you confirm as to whether the motor has a tack wheel on the rear?.
Max.

Hi Max, I have the same issue listed in this thread. I am convinced my issue is coming from the op panel as my house circuit breaker still trips with both the belt motor and incline motor disconnected from the board. The motor trips before it turns after I press the start button. I have run the motor on a 12V battery and also on a makeshift circuit with a 240V->24V AC transformer into a Bridge rectifier, motor spins up fine and not tripping the breaker.
The MC board is new and powers up fine and the console powers up fine, incline motor works, but once I press the start button the house breaker trips, interestingly the treadmill breaker does not trips. I figure I either have an earth leak when the signal from the start button is sent to the MC board or the signal from the op panel when I press the start button is requesting too much power from the motor and it trips the circuit before starting. But I could be way off. Please help of you can? The only other interesting piece of info is, I was having the same problem, I bought the nee MCB, treadmill worked under load for 20 min then tripped, now trips every time the start button is pressed regardless if appliances are attached to board or disconnected from board.

 

Have you tried a start with the motor disconnected? Also with a lamp in place of the motor, press start and see if the breaker trips.
Max.

 

Have you tried a start with the motor disconnected? Also with a lamp in place of the motor, press start and see if the breaker trips.
Max.

Hi Max,

thanks for the reply.
Yes have started with motor off, and both motors off, with console plugged in. The house circuit breaker trips when I press the start button. I wil have to find something to add the DC circuit like a lamp to see what happens.
Any thoughts on where I should be looking? Speed sensor? ...?

 

Doesn't sound like an O/L caused by the speed sensor.
Especially if it trips the breaker when start is issued.
To trouble shoot the board you need to test it on the bench, but for this you need a PWM command board to simulate a start command.
Otherwise it is removing power items and see if the breaker hangs in, isolate the board from ground and see if it trips the breaker.
Max.

 

Doesn't sound like an O/L caused by the speed sensor.
Especially if it trips the breaker when start is issued.
To trouble shoot the board you need to test it on the bench, but for this you need a PWM command board to simulate a start command.
Otherwise it is removing power items and see if the breaker hangs in, isolate the board from ground and see if it trips the breaker.
Max.

Hi Max. Yes I did that, I removed all earth connections from the board, except for the earth that comes in as part of the power cord. The breaker still tripped, that I think indicates that the MCB is asking for too much power and this trips the circuit before motor starts? (Runaway condition?) Is there a cheap way to simulate pressing the start button to remove or confirm the issue is with the op console? How does one fix a runaway condition ( assuming this is the Problem?

 

Hi Max, I know I am a little all over the shop here but I just did another test and between the motor output on the PCB and earth I am getting 155V. This is over the DC motor rating of 130V, not sure if that is a problem? Or how to fix it if it is.

 

Just to confirm, does the breaker trip with no motor connected? and/or what was the result of using a lamp in place of the motor?
Max.

 

Hi Max,

Yes the house breaker trips with no motor connected once the start button on the op panel is pressed.

lamp test will happen later today, i just need to find an old globe I can use.

when the motor is attached, there is no motor movement before the trip.

 

So if the breaker trips with no motor then the lamp test may not be needed.
Is this just a problem with this board? Or did the first board do the same thing?
If he motor BEMF diode on the H.S. is shorted, it could cause this problem.
Max.

 

Hi, first board did the same thing. Second board ran for 30 min before doing the same thing. So you are thinking one of the diodes is gone on the board... why would that happen again? Is the motor bad?

and do you have a layout of the MC2100ELS board so I can identify that diode that you reference?

 

Here is a picture of the old board minus the rectifier.