Help with Motor Control Board - ProForm treadmill

[Aglass0fmilk]

Re: Help with Motor Control Board

Sorry for the double post. Here are some pictures from my repair so far.

I used a Hakko FX-888D soldering station set to 360C with a sizeable tip. Pick up some desoldering braid/wick, I used 2.5mm wide solder wick. You should also get some flux to help the solder flow into the wick and generally make things easier, I recommend Chipquik SMD291.

The traces are pretty fried, desolder the components carefully because you can easily rip the overheated traces off the board or damage the through holes.

The 1K resistor exploded a bit and was open circuit when I did a continuity test on it. You can see some of the exposed windings under the microscope!

I hope this info helps people repair their old treadmills!

[Aglass0fmilk]

Re: Help with Motor Control Board

Mark - can you give the locations of the components you replaced?

1x 24v 5W zener diode
1x 15v 1.3W zener diode
1x 1N4007 rectifier diode (general purpose)
1x 1K 10W ceramic resistor

I am fixing this board for my sister's treadmill at the moment. The same issue -- the motor controller board got a bit toasty in this area.

My board revision is a bit different -- instead of one 24V zener there are two 12V zeners in series with the reference designators DZ4A and DZ4B. They must have gotten a good deal on 12V zeners...

Anyways, based on my teardown and repair, the components above map to:

• DZ4 = 1x 24v 5W zener diode
• DZ1 = 1x 15v 1.3W zener diode
• D11 = 1x 1N4007 rectifier diode (general purpose)
• R57 = 1x 1K 10W ceramic resistor

The reference designators may be different on your board, but probably not. Mine were the same as the OP based on their pictures, aside from having two 12V zeners (DZ4A and DZ4B) making the 24V zener (DZ4)

I've attached some pictures for reference in case the designators are different for whomever reads this next.

I plan to fix the traces with some wire or copper tape I have lying around. I will then cover the repaired traces with a green overcoat pen.


The parts I ordered are as follows:

• Vishay Dale CW0101K000JE73 RES 1K OHM 13W 5% AXIAL
• Central Semiconductor Corp CZ5359B TR PBFREE DIODE ZENER 24V 5W DO201
• onsemi 1N5929BRLG DIODE ZENER 15V 3W AXIAL
• CAIG Laboratories, Inc. HSC67-6G SILICONE HEAT SINK COMPOUND
• MG Chemicals 419D-P-GR OVERCOAT PEN GREEN

NOTE: I do not guarantee these are correct for your application so only attempt this repair if you know what you're doing; I am not liable for any damages caused by the use of these parts.

[ken1415]

Re: Help with Motor Control Board

Hey all, Again this old thread was helpful for me getting my MC70 treadmill motor control board running.

For future individuals looking to repair their boards, here's what I replaced:

1x 24v 5W zener diode
1x 15v 1.3W zener diode
1x 1N4007 rectifier diode (general purpose)
1x 1K 10W ceramic resistor

I had to bridge / repair the fried traces on *both* sides of the 24v zener diode. I simply used leads from a spare 1N4007 that was handy.

The zener diodes were easy to spot & the resistor was replaced as a preventative measure. Mine was showing evidence of overheating with a white-ish color.

The 1N4007 is the one at the end of the 1K resistor, where the AC connection is made. In my case, it looked ok but tested bad and was something I had on hand, so replacing it was an easy choice. Without replacing this diode - the board appeared to be completely dead.

After replacing the above components, I cleaned off the old thermal paste and installed a thin coating of new paste.

I hope someone finds this information helpful. My repair cost less than $20 CAD, plus shipping.

Cheers,
-Mark

Mark - can you give the locations of the components you replaced?

1x 24v 5W zener diode
1x 15v 1.3W zener diode
1x 1N4007 rectifier diode (general purpose)
1x 1K 10W ceramic resistor

[4umfreak]

Re: Help with Motor Control Board

Hey all, Again this old thread was helpful for me getting my MC70 treadmill motor control board running.

For future individuals looking to repair their boards, here's what I replaced:

1x 24v 5W zener diode
1x 15v 1.3W zener diode
1x 1N4007 rectifier diode (general purpose)
1x 1K 10W ceramic resistor

I had to bridge / repair the fried traces on *both* sides of the 24v zener diode. I simply used leads from a spare 1N4007 that was handy.

The zener diodes were easy to spot & the resistor was replaced as a preventative measure. Mine was showing evidence of overheating with a white-ish color.

The 1N4007 is the one at the end of the 1K resistor, where the AC connection is made. In my case, it looked ok but tested bad and was something I had on hand, so replacing it was an easy choice. Without replacing this diode - the board appeared to be completely dead.

After replacing the above components, I cleaned off the old thermal paste and installed a thin coating of new paste.

I hope someone finds this information helpful. My repair cost less than $20 CAD, plus shipping.

Cheers,
-Mark

[80wa7113]

Re: Help with Motor Control Board

Well, there was just going to be NO fixing this board. I replaced my fried zener diode (DZ4) and also replaced the other DZ4 as well as DZ2 and the accompanying resistor with no luck. Without a schematic it is next to impossible to properly diagnose the failing component. Searches of the internet only came up with guys who repair the boards...BUT I also found a company called Gemini Controls out of Wisc. who makes the latest generation of PWM's to fix these DOA treadmills. Their NEW board was $149.00 - about $10 more than having this one repaired. I opted for new with a thin price difference like that.

Installed the new board and we're up and running again!

Old board heading to the landfill....

[80wa7113]

Re: Help with Motor Control Board

Hi Crrose,

I realize this thread is almost a couple of years old, but, did you ever get this issue resolved? I found your thread while doing research for the exact same problem I'm having with yet another failed MC70 motor control board...no motor start with a burned board at DZ4A/B.

Regards,

Dave

[Crrose]

Re: Help with Motor Control Board

by any chance to the braking resistors get hot when its running? the relay might not be dropping out.

What are the braking resistors?

And yes I will post pictures of board with new pieces on.

[goontron]

Re: Help with Motor Control Board

by any chance to the braking resistors get hot when its running? the relay might not be dropping out.

[budm]

Re: Help with Motor Control Board

Let us see the pictures after the parts installation first.

[Crrose]

Re: Help with Motor Control Board

I bought extra so will try to redo it one more time and see what happens. Bought 3 TC chips but for some reason only 2 of the other mosfets.

[budm]

Re: Help with Motor Control Board

Well I replaced the TC1410 chip and the W33N20 mosfet, turned treadmill on and motor no longer started on its own at high speed which was good news, but, it acted like it was prior to me shorting out the mosfet. After maybe a minute the W33N20 popped and spit out some smoke underneath the board and shorted out.

The motor is connected in series with the MOSFET, if it shorted out the motor would have been running full speed (MOSFET is basically connected in series with the motor).
Are you sure everything is connected properly, and the soldering works are good?

[Agent24]

Re: Help with Motor Control Board

Bummer. Sounds like something else is still wrong causing the MOSFET to blow.

[Crrose]

Re: Help with Motor Control Board

Well I replaced the TC1410 chip and the W33N20 mosfet, turned treadmill on and motor no longer started on its own at high speed which was good news, but, it acted like it was prior to me shorting out the mosfet. After maybe a minute the W33N20 popped and spit out some smoke underneath the board and shorted out.

[Crrose]

Re: Help with Motor Control Board

Just and update on status, still waiting for parts from china.

[keeney123]

Re: Help with Motor Control Board

To desolder the SMD could you not just cut the legs of the bad SMD and desolder them one at a time? They also make a low temp solder that you could add the the solder on the SMD and that will lower the melting point of the present solder on the SMD so you can heat all the pins of the SMD and before they cool down below the lower melting point you would be able to remove the SMD and then go over the pads with solder wick to clean them up.
To solder the SMD one has to first tack it down on two opposing corners then it is also, good to use a hoof tip that has a little reservoir for solder. You would put flux down and put a little solder in the tip of the iron and then drag the iron on the outside of the pins making contact with the pad and pin at the same time and only adding a little solder if needed. You would start at the opposite side of the pins you tacked down.

[Crrose]

Re: Help with Motor Control Board

Very tedious and difficult. Small resistors and caps are ok since it's one leg at a time but doing SMDs very difficult. Looking for a cheap hot air gun or how to make one. Still waiting for parts to arrive, apparently they are shipped from china. Got the small TC1410 from Mouser but couldn't find the W33n20 anywhere else.

[keeney123]

Re: Help with Motor Control Board

How the soldering experiment coming along?

[Crrose]

Re: Help with Motor Control Board

Need to get some old circuit boards to mess with. Checking craigslist for free electronics.

[selldoor]

Re: Help with Motor Control Board

Watching videos is fine but you need to do some as well?

[Crrose]

Re: Help with Motor Control Board

Still waiting for parts to arrive watching videos on how to remove and solder the small SMD.