Gotcha.. but I should be able to diode test pins 1 and 2 on U1 and Im getting an open link. But on U2 the anode/cathode test good.
I went looking for another optocoupler and found a CNY17F on a Power Systems Pulse 3 TM motor controller. It's a 6 pin model but two are not used internally. Comparing the specs they are very similar.. the CNY has 60mA versus 50mA FwdCurrent and 100mW of power dissipation versus 70mW on the U1.

Max, Any advice on what to try at this point? As a refresher the controller powers up, led blinks when PWM signal is recieved. But regardless of duty cycle output DC voltage remains at 0, motor never operates. In the absence of a motor/load, DC output voltage is 150+.

Maybe I should have started a new thread

 

Did you try with load such as a incandescent lamp etc?
The 817 4 pin opto is quite commonly available?
LTV817, PC817 etc.

 

I did not.. crap yeah I should do that before trying to solder anything else.

Yeah availability online I'm sure.. the 817 is everywhere. I just have no local sources available and I get quite anxious, need to do a thing right now, sort of person.

 

Aaand in typical fashion.. I got in too big of a hurry and desoldered U1 without testing with a lighting fixture

Found it really weird though.. when U1 removed, and with better access to the legs, I'm still reading an open on the diode side. Also, even doubly weird, the CNY17F also fails on it's diode! Well since it's off Im going back through all of my scrap in the hopes I find another 817. Maybe I'll solder jumper wires to the board to make this easier.

 

Can I ask.. with normal LED's using the diode function on an MM works well. On these optocouplers.. the 817 and CNY neither beep using the diode function but I do read .754M ohms and only in the right direction. Nothing in the opposite direction or reversed MM leads.

Ok so original 817 has been resoldered back onto the board. Replaced motor with lightbulb, zero voltage at the bulb even though the status led is blinking from the PWM signal.
This is just.. so frustrating, and strange.

 

Sounds like something in either the Mosfet driver, usually a MIC4427 or in the Mosfet itself, probabally requires a 'scope to trouble shoot.

 

Hmm, well that sucks. You're obviously very smart on this topic, can I ask... How does this circuit detect whether there is a load or not?
Second, So initially I was powering the PWM generator off the 12v from HD2, the guy earlier in this thread was using the INS header for 5v. Since you mentioned the need for a resistor on the PWM side, and since that guy was using the 5v versus 12 I decided to flip over to the 5v myself. I had to jump the duty cycle to 80%+ in order to read any higher than 1vdc from the PWM.
So taking into account that you can't accurately measure PWM using a MM, but since the original diagram sheet mentioned 1.5vdc. Will the PWM side of this operate correctly with so much less voltage?

 

The current is monitored by the micro via a 0.01Ω in the source lead of the Mosfet.
The PWM should provide sufficient current in order for the 817 Opto to conduct somewhere just below its rated LED current.

 

Ahh ok I was wondering whether the PWM was voltage or current based. So looking at the specs for the 817 am I correct in understanding the diodes max current is 50mA?
And just rechecked the 'new' 260 mosfet... its gone just like the previous one. A short between pin 1 and 2 and 2 and 3.

 

Another issue to check is the DC supply ramp-up circuit done via the SCR on the DC supply.
And Yes the max opto LED is 50ma, so the resistor is sized accordingly

 

The TD3052 triac yes? For the opto diode, the on-board 22ohm resistor is/is not enough for an external PWM generator?

 

Triac S4025 on many boards.
As you mentioned, the opto input is limited to 50ma, so the suitable series resistor is chosen based on the PWM voltage +ve level.

 

Thanks for your time and brains Max. I think Im just going to ditch this controller.. try to find another freebie TM and start from a known good controller. I just dont have the time or equipment to do this stuff properly.

 

What do you mean by "Ditch it"?

 

Oh I just mean tossing it into the scrap pile, stop wasting time with it.

I'm all for fixing things if at all possible but the mosfets blown once, now there's something else going on that I can't validate without probably, an O-scope and the skills to use one.

 

Oh I just mean tossing it into the scrap pile, stop wasting time with it.

I'm all for fixing things if at all possible but the mosfets blown once, now there's something else going on that I can't validate without probably, an O-scope and the skills to use one.

Hi. Jumping back on this. I am in now way electrical but a dabbler but having tried various replacement components as suggested, sourcing a second used controller (and motor actually), I bought a new controller from Pro form and put that in. Needless to say it worked treadmill started up no blown fuse issue. BUT...the treadmill isn't perfect. It slows when applying load to the belt; the faster it runs and heavier the load the more it is held back. Tried the usual things suggested for such a fault (belt tightness, lubrication etc) and the only thing I can think is the motor is shot? Any thoughts on this? It's spins and runs and doesn't seem to be making odd noises...but given these things are essentially a controller and a motor I can't see what else could be at fault?

 

What means of belt speed does it employ?
Some are proximity sensor on the side of the belt pulley.
Check the sensor for distance.

 

What means of belt speed does it employ?
Some are proximity sensor on the side of the belt pulley.
Check the sensor for distance.

It is a sensor that is a proximity sensor/magnet adjacent to the roller of the belt. In what way would this cause an issue if too close/far away? And is there a way to know how close it should be?? Thanks

 

It is normally around 2mm - 3mm gap, some times, vibration moves it away from the magnet or trip flag.

 

It is normally around 2mm - 3mm gap, some times, vibration moves it away from the magnet or trip flag.

Thanks will check. Would this cause a dragging when the belt is loaded?