Another treadmill motor board problem

Thread Starter

dpyle

Joined Sep 1, 2012
5
Hi, I have an Ironman 220t treadmill with a Keys Health board p/n 08-0158.
The problem is I can power up the treadmill and everything is fine. But as soon as I start the belt motor F2 blows. I can use my cordless drill battery and run the motor, so it seems good. I don't see any marks or anything on the board. Anyone with any ideas where to start?

Thanks
 

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Rbeckett

Joined Sep 3, 2010
208
I would start troubleshooting by pulling the plug at te motor. The system will then send all the signals to the motor, but it wont apply that load. If the fuse still pops, look into the board and folllow that circuit till you find the shorted componrnt. If the fuse doesnt pop that confirms that you have a short inside the motor or the wiring leading to the motor. That should at least get you started locating where the issue is. Remember that you are working with mains energy unplug and allow the caps to run down bbefore you put your hands in and get bitten. Avoid contact with the caps still, just in case they contain a residual charge.
Bob
 

Thread Starter

dpyle

Joined Sep 1, 2012
5
OK, the fuse still pops with the motor disconnected. So that means the problem is in the board. My question now is when tracing back I run into rectifiers and capacacitors. Nothing looks burnt. How do I check these?

Thanks
 

Thread Starter

dpyle

Joined Sep 1, 2012
5
OK, but how do I check the chips, rectifiers, and caps. I think I remember a plain diode will conduct one direction, but not the other, right? The ones that I'm not sure of though are the rectifier packages, the three legged and four legged variety (I assume they are rectifier packages). :confused:
 

wayneh

Joined Sep 9, 2010
17,153
Others may have different ideas, but I'd be very suspicious of the power transistors that drive the motor. If one of them failed as a short to ground, that would blow fuses.
 

Thread Starter

dpyle

Joined Sep 1, 2012
5
Thanks Wayneh, thats bkinda what I was thinking. If you look at the pictures, to my knowledge (which isnt muxh) I see only one transistor. If I unsolder it, how do I test it?
 

gerty

Joined Aug 30, 2007
1,302
I would also check the bridge rectifier (marked BD1, lower left first picture).
That too should be removed from board to be checked.
You would check the bridge by using a meter in the "diode" setting and check across all the pins one pair at a time. An obvious short should give you a
".000" reading.

When removing any components for checking, always make a note of the parts orientation so that you don't put them back in backwards.
 
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wayneh

Joined Sep 9, 2010
17,153
When removing any components for checking, always make a note of the parts orientation so that you don't put them back in backwards.
+1
Trust me, that's sage advice. ;) Been there, failed to do it.

Those big black, 3-pinned components that stand vertically off the board - those are potentially the power transistors. It looks like one of them is Q11. They can also be tested with your meter's diode tester (after removing them from the board).
 

Thread Starter

dpyle

Joined Sep 1, 2012
5
So if I get a .4190 across a couple pins and an open (OL) across others it is good? (using a digital meter with a diode setting).
 
Hi, I have an Ironman 220t treadmill with a Keys Health board p/n 08-0158.
The problem is I can power up the treadmill and everything is fine. But as soon as I start the belt motor F2 blows. I can use my cordless drill battery and run the motor, so it seems good. I don't see any marks or anything on the board. Anyone with any ideas where to start?

Thanks
Could you please give the R64 value?
 

ThePanMan

Joined Mar 13, 2020
94
Others may have different ideas, but I'd be very suspicious of the power transistors that drive the motor. If one of them failed as a short to ground, that would blow fuses.
That was my first thought.

Something I've done in the past has been to replace the fuse with a light bulb. No, not pulling the fuse holder and replacing it with a lightbulb, just soldering the ends of a blown fuse to a couple wires going to a lightbulb. Then, if there's a dead short the light bulb will glow normal brightness.

I also recommend the sage advice of being damned careful about handling live components. 120VAC bites pretty good. And under the wrong condition it could be the last time you ever mess with electronics. Mess with anything. So be very careful. And I would remove the transistors and check all of them - the big ones on the left edge of the board as shown in your picture.

I would also check the bridge rectifier (marked BD1, lower left first picture).
That too should be removed from board to be checked.
You would check the bridge by using a meter in the "diode" setting and check across all the pins one pair at a time. An obvious short should give you a ".000" reading.
I would suspect that if the BR was shorted (and I've had that condition before) the main fuse would blow as soon as the board was powered. Since this is only blowing when the motor is being energized I would tend to not suspect the BR. However, you never know. I still like the lightbulb trick for troubleshooting. Had a stereo with a shorted BR. The lightbulb helped me zero in on the problem. Once fixed, the light bulb would glow bright as the caps charged but then quickly extinguish.
 
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