Help with Motor Control Board - ProForm treadmill

[philliesfan30m]

Re: Help with Motor Control Board

if both of those diodes read 0 both ways then they are both shorted. as toasty stated in post 13 you should check those 2 diodes dz1 and dz4 and budm stated in post 7. i'm not the best troubleshooter but i would bet those 2 diodes are part of the problem if not the complete problem just from looking at the burn marks on the board. you said they read 0. is that with the leads of the dmm reversed also? if so you would have to desolder a leg and retest to make sure. if they do read 0 both ways they are both shorted.

[budm]

Re: Help with Motor Control Board

If we can get good clear pictures of the top and bottom side of the board, that will help troubleshooting a lot.

[Crrose]

Re: Help with Motor Control Board

The 2 diodes start with a reading but immediately go down to zero on. That is with the leads reversed also. Here is a top and bottom view of the board. The mounting plate and heat sink had to be removed for the photos. I also checked the black/white/red wires that are supposed to read 5v but they fall well below that at around 3v.

[Crrose]

Re: Help with Motor Control Board

Any idea what size these to diodes are? All I can see on DZ1 is 5Ph and on DZ4 24-C838.

[budm]

Re: Help with Motor Control Board

They may be 5V and 24V, but best way to test is to lift one leg off the board to get better reading.
Can you the numbers on Q4 and the one next to it?
I will look at the board layout using your pictures, I may ask for more close up pictures later on.

[Crrose]

Re: Help with Motor Control Board

Ok Q4 has ST Morocco 9540 427654 W33N20 on it and the smaller D4 has 98-39 U1520 on it.

[Toasty]

Re: Help with Motor Control Board

As I said about 10 posts ago...

[Crrose]

Re: Help with Motor Control Board

Ok I changed DMM's because the other was acting to erratic. When I test the 2 zenner diodes now DZ1 reads 005 and DZ4 reads 007. The registers the same with the leads reversed also.

[Crrose]

Re: Help with Motor Control Board

I just tested D4 and Q4. When I place the black lead to the left leg and red to the right I get a reading of 414 and if I reverse the leads there is nothing.

On Q4 black to 1st leg and red to middle, nothing. Black to 1st and red to 3rd I get .094.
Black to 2nd leg and red to 3rd I get .521.
Red to 1st and black to 2nd I get .611.
Red to 1st and black to 3rd I get .112.

If that helps at all.

[budm]

Re: Help with Motor Control Board

Ok I changed DMM's because the other was acting to erratic. When I test the 2 zenner diodes now DZ1 reads 005 and DZ4 reads 007. The registers the same with the leads reversed also.

Did you lift one leg off the board?
Also check them using Ohm mode.

[Crrose]

Re: Help with Motor Control Board

That was with them still attached to board. I'll try my hand at desoldering.

[Crrose]

Re: Help with Motor Control Board

Removed one leg of diodes from board and when set at 200ohm I get .6 on DZ1 and 1.4 on DZ4. If it is set to diode mode I get .001 and .002 with continuity.

[budm]

Re: Help with Motor Control Board

"I get .6 on DZ1 and 1.4 on DZ4"
They are bad.

[Crrose]

Re: Help with Motor Control Board

So I need a 24v and a 5v. Are they all the same except for the voltages?

[budm]

Re: Help with Motor Control Board

So this the virtual PCBA I come up with, hard to trace out double-sided PCB.
The motor is driven by the power MOSFET.
One of the black power resistor is for soft-start, another one is for Voltage drop for the Zener diode.

[budm]

Re: Help with Motor Control Board

With the diodes removed, you can see the whole numbers as printed to verify the Voltages. They look like 1W ZENER.

[Crrose]

Re: Help with Motor Control Board

The black one broke in half when I tried to remove it from the board (after I got the reading) that was the 24v one. Can I go up in wattage if I can't find a 24v 1w?

[Crrose]

Re: Help with Motor Control Board

DZ1 says C15PH

[budm]

Re: Help with Motor Control Board

That will be 15V Zener, if the legs will fit the holes then I would go with higher Wattage.
I would also mount them with body above the board like 0.100"~0.250" to allow better air flow.

[stj]

Re: Help with Motor Control Board

5w is good, next one down is 1.3w