Help with Motor Control Board - ProForm treadmill

[keeney123]

Re: Help with Motor Control Board

are you sure it is the + side of the cap and not the negative side?

[Crrose]

Re: Help with Motor Control Board

From source to large cap - I get .5 ohm when meter set at 200. Thats with no power to it,

[Crrose]

Re: Help with Motor Control Board

I just removed board again and it looks like the source pin is connected to the + large cap.

[keeney123]

Re: Help with Motor Control Board

I guess one could just ohm out the connection from the source pin to the negative of the filter cap to find out the answer to BudM's question.

[keeney123]

Re: Help with Motor Control Board

Are you sure the drive motor only get 24 volt dc? In the voltage wiring diagram it says the drive motor goes from 0V to 120 VDC, but if it only gets 24 volts then all that would be is the negative motor terminal just needs to be 24 volts less than the positive motor terminal. So if the positive terminal is 160 volts DC the neg terminal would need to be 136 volts DC. That would give one 24 volts DC across the motor. I would make the measure of the positive motor terminal to the negative of the cap to make sure the positive voltage is indeed making it there.

[budm]

Re: Help with Motor Control Board

Base on what I can see from the pictures:
The metal is the high Wattage current sensing resistor to provide feedback to keep the motor running at the constant speed so when the load is changed (body weight varies).
The B+ of cap is connected to one end of the sensing resistor, the other of the resistor is connected the M+ of the Motor, the M- of the motor is connected to the Drain of the POWER MOSFET, then the diode (to-2220 case) is connected in parallel with the Source and Drain to handle the back EMF from the motor since the body diode inside the MOSFET will not be able to handle it.
The question is I cannot see how the Source pin is connected, need to see if the Source pin is connected to the - of the filter cap or not.

[keeney123]

Re: Help with Motor Control Board

Seems to me the diode connecting B+ to the drain would short out the motor connection because the B+ is connected to the + motor connection through R3 and the -motor connection is connected to the drain?
But now we should see the B+ voltage now on the + motor terminal through R3.

This brings me back to the diode.The diode in BudM picture seems to be shorting out the motor.

[Crrose]

Re: Help with Motor Control Board

Been raining hard here all morning and football on so haven't gone to get those wire wound resistors yet, will probably go tomorrow unless rain stops.

Keeney123: I have no idea either what that metal strip is (it's actually labeled R9) that connects M+ to the big caps + other then just a simple way to connect the 2 together. Plus Q4 source appears to be connected to the bridge rectifier, could that be what changes it to 24V?

[selldoor]

Re: Help with Motor Control Board

R3 is wrong I meant R5, talking about BudM image post 128 with components drawn in the bottom of the SCR board. The R5 seems to me to be a metal bracket viewed from the top of the board. This R5 seems to connect the Caps + side to the + side of the motor. I am not sure why BudM calls it R5 as it looks like a piece of metal? I am saying if one puts the black probe of the meter to the neg side of the caps and the positive lead of the meter to the positive side of the motor connection then the 160 DC voltage should be there because R5 connects the Caps + to the Motor +. If I understand R5 correctly?

Yes I think that is correct, but crrose has already established he has 160vdc at the BIG caps (he originally had the test wire soldered to the wrong place)
It does get me back to what I was asking about how is the voltage reduced to 24v to the motor.
One side of the motor M+ we seem to agree is connected to 160v+ at the BIG Cap so looking at the M- that is connected to the Drain of Q4 and the Source of Q4 - is that going to be connected to Big Cap-160vdc ??

In that case the 160v must be reduced to 24v by the mosfet?? so what tells
the mosfet to reduce it to 24v as against 50v or10v?

[keeney123]

Re: Help with Motor Control Board

Seems to me the diode connecting B+ to the drain would short out the motor connection because the B+ is connected to the + motor connection through R3 and the -motor connection is connected to the drain?
But now we should see the B+ voltage now on the + motor terminal through R3.

R3 is wrong I meant R5, talking about BudM image post 128 with components drawn in the bottom of the SCR board. The R5 seems to me to be a metal bracket viewed from the top of the board. This R5 seems to connect the Caps + side to the + side of the motor. I am not sure why BudM calls it R5 as it looks like a piece of metal? I am saying if one puts the black probe of the meter to the neg side of the caps and the positive lead of the meter to the positive side of the motor connection then the 160 DC voltage should be there because R5 connects the Caps + to the Motor +. If I understand R5 correctly?

[keeney123]

Re: Help with Motor Control Board

Look at the image in post 128

[Crrose]

Re: Help with Motor Control Board

I guess i'll finish up for today and try to get those resistors replaced.

[Crrose]

Re: Help with Motor Control Board

Good call Selldor, I just checked in diode mode and getting all the readings like before. I'll also look for the resistor you just posted.

[selldoor]

Re: Help with Motor Control Board

You know I did this the other day looking at my notes and at that time I had:

A: black pin 1 red pin 3 = 94
B: black pin 2 red pin 3 = 521
C: red pin 1 black pin 2 =611
D: red pin 1 black pin 3 = 112

Think you had it on diode setting then though?

[selldoor]

Re: Help with Motor Control Board

Well I think we know what one of them might be.

I reckon TVM10J1KO

http://oneic.com/s/tvm10j1k.html

So that is a wirewound 10watt 1Kohm I think?

[Crrose]

Re: Help with Motor Control Board

You know I did this the other day looking at my notes and at that time I had:

A: black pin 1 red pin 3 = 94
B: black pin 2 red pin 3 = 521
C: red pin 1 black pin 2 =611
D: red pin 1 black pin 3 = 112

[Crrose]

Re: Help with Motor Control Board

A: black pin one and red pin 2 no reading
B: black pin one and red pin 3 the longer I hold it the higher it goes, removed when 94
C: black pin 2 and red pin 3 no reading

[selldoor]

Re: Help with Motor Control Board

"In post #35, Budm mentioned the motor is driven by the power mosfet." - I will re read

This a test for mosfet but I dont think it can be shorted
If you have a manual range multimeter, set it to 200 ohms (two hundred). You can test a mosfet (Q, IC designation) "in circuit" by (power off and unplugged)

a) black on pin 1- red on pin 2 - record ohms
b) black on pin 1- red on pin 3 - record ohms
c) black on pin 2- red on pin 3 - record ohms

If any ohm reading is less than 30 ohm you might have shorted mosfet. Remove from circuit and repeat the tests to verify.



Resistors - not caps - resistance measured with meter on ohms.

Sometimes the resistance does not show correctly as it may be affected by other components so you have to lift at least one leg to isolate it - In this cas lifting one end may damage the resistor, hence removing it.

Next time the board is out have a look at that bottom joint - first have a look on the pictures- even a poor resolder attempt might be better than it is?


EDIT hehehe - you changed your post while I was working on an answer
Just try testing th eresistors on the board and see what they test at.

[Crrose]

Re: Help with Motor Control Board

In post #35, Budm mentioned the motor is driven by the power mossfet. Is there a way of checking that or bypassing to test?

My soldering skills aren't that great so I try to avoid as much as possible, kind of afraid of removing the caps to test resistance, besides I don't have an ESR meter.

I guess If I need to unsolder the resistors I might as well replace them if I knew what to buy. No markings on them.

[selldoor]

Re: Help with Motor Control Board

me neither - keeney123 can you shed light on my earlier query re how it gets from 160vdc down to 24 vdc. to drive the motor.

crrose- question I dont think you answered "what is the resistance on the two big resistors." - That also lead me to looking at the solder joints on them and
the bottom joint of one of them looks pretty bad. To test the resistance you will probably have to unsolder them, which is an opportunity to remove the old solder and use fresh. Need to be careful though, dont want to snap them.
In the picture of the reworked board oe had been replaced by a White one.