Problem with PWM control of a Treadmill DC motor

Thread Starter

JMacG

Joined Oct 12, 2021
15
Hi there - Could someone help me out with a PWM DC motor control problem I've got at the moment.

I've bought a Tunturi T80 treadmill motor and speed controller board for a lathe project I'm working on at the moment. Apparently, it needs a PWM input to control the speed of the motor, so I bought a recommended unit from an on-line retailer after watching some YouTube videos. Unfortunately, this came without instructions, but is has the four connections (V+, V-, ground, PWM). I managed to find a connection diagram (see attached) on the internet for the speed controller board and wired it to the PWM unit as follows.

PWM: pin 6
Ground: pin 7
V+: pin 1
V-: pin 8

The screen is illuminated on the PWM unit but no amount of fiddling will get the motor to run. Could someone advise me on what I might have got wrong.

Regards
JMacG
Connector.jpg
 

MaxHeadRoom

Joined Jul 18, 2013
26,004
Most of the PWM TM controllers out there are aimed at the MC2100 boards and output a 20hz PWM signal.
Also the output is into an Opto isolator on the board which also needs a series resistor.
Are you sure the unit you bought is compatible?
 

Thread Starter

JMacG

Joined Oct 12, 2021
15
The MC2100 boards seem more popular in the USA rather than here in the UK. I also understand there are more circuit drawings for these types of boards also. Unfortunately, I couldn't find any circuit drawings for the Tunturi T80 board. I think I was lucky to find the connector diagram. Consequently, I can't say if the board I have is compatible with the PWM controller purchased. I think I'll try my luck and contact Tunturi here in the UK to ask if they would send me a circuit diagram for the T80 controller board, however, I suspect they might just tell me to get lost.

Regards
JMacG
 

MaxHeadRoom

Joined Jul 18, 2013
26,004
I think I'll try my luck and contact Tunturi here in the UK to ask if they would send me a circuit diagram for the T80 controller board, however, I suspect they might just tell me to get lost.
Yes, most manuf perceive the technical information proprietary and are loath at releasing anything.
You could ask on the details of the required signal?
 

MisterBill2

Joined Jan 23, 2018
13,206
Any decent supplier will provide information for the products they sell. Thus I refuse to consider many of the dealers that can only supply price and shipping weight information.
Any decent company would provide at least basic application connection information for using the product they sell. External connections are not proprietary information.
 

MaxHeadRoom

Joined Jul 18, 2013
26,004
Any decent supplier will provide information for the products they sell. Thus I refuse to consider many of the dealers that can only supply price and shipping weight information.
Any decent company would provide at least basic application connection information for using the product they sell. External connections are not proprietary information.
This is a case of a domestic product, and with TM's, most cases anyway, and producers /vendors of these units very rarely ever supply service technical information to the end users.
Especially when as in this case, the requester of the information intends to use a part of the unit for other purposes
Any that comes to light, is usually stamped proprietary and not for public use.
Plus, many domestic products, such as this, posses microprocessors where the security fuse is used to prevent copying.
This is why much of this type of equipment (TM's) has been reverse-engineered by individuals that fortunately pass it on to sites such as this.
 

Thread Starter

JMacG

Joined Oct 12, 2021
15
I contacted Tunturi in the UK but they said they couldn't help me without a treadmill serial number, which I don't have. So, I've decided to abandon the PWM controller board that came with the motor and instead will use an SCR circuit. There seems to be a lot of information on the internet about this type of motor control, so that seems to be the way to go. It would also stop me going round in circles with the Tunturi controller board.
 

MaxHeadRoom

Joined Jul 18, 2013
26,004
The only thing is the PWM is a far smoother control than using a SCR bridge for e.g..
Without feedback, you may get "cogging" at low RPM's.
 

Thread Starter

JMacG

Joined Oct 12, 2021
15
OK, thanks for that info. Are there commercially available PWM controllers that could be used for this application? The motor is rated at 260 Volt DC, 8A.
 

MaxHeadRoom

Joined Jul 18, 2013
26,004
There is KB Electronics that manuf. a range of DC/BLDC motor controllers, if you can get them in the UK.
BTW, the TM's that use the MC2100 must be around in the UK, as I helped someone online fix one once.
 

MisterBill2

Joined Jan 23, 2018
13,206
Automation Direct has a line of motor drivers that are reasonably priced and well supported technically. And they sell direct so you are dealing with the company that can provide the information you need.
 

MaxHeadRoom

Joined Jul 18, 2013
26,004
KB are the manufactures and can be dealt with direct also.
I am not sure if Automation Direct sell a PWM version in that voltage/HP range.
I would not give up yet on the original board yet, can you do a little reverse engineering to see where the PWM input signal ends up on the board?
 

MisterBill2

Joined Jan 23, 2018
13,206
Automation direct sells complete drives, ready to connect the motor and go, although you often need to key in setup information for the motor. And they do sell the drives for the smaller motors.
It appears that AD has realized that not everybody is using 10HP 480 volt 3phase motors.
 
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