Help with Motor Control Board - ProForm treadmill

[budm]

Re: Help with Motor Control Board

"But what about the -49 on the other filter."
OK, please do the resistance testing between the Negative legs of the two cap and between the positive legs of the two caps to see if they are connected in parallel with each other or not.
It also sounds like you may have intermittent connections some where sine the relay is now kicks on.

[Crrose]

Re: Help with Motor Control Board

Ok I get a reading when I test them together, 1.962 on negative and .522 on positive.

[budm]

Re: Help with Motor Control Board

Ok I get a reading when I test them together, 1.962 on negative and .522 on positive.

So the resistance reading of the negative leg of one filter cap to another filter cap negative leg is 1.962 Ohms, and the resistance between the positive leg of one leg to another positive leg is 0.522 Ohms?

[Crrose]

Re: Help with Motor Control Board

Yes

[budm]

Re: Help with Motor Control Board

So basically they are connected in parallel if the resistance are that low which means the DC Voltages on the legs of both cap should be around 160VDC, so I am not sure how you get -49VDC on one of the cap.

[Crrose]

Re: Help with Motor Control Board

I have tested them several times and the one closest to the relay has 166.6 and the other -49. If I switch it to AC that ones gives reading of 63.2VAC

[Crrose]

Re: Help with Motor Control Board

Going to take a break from it for the night and start up again tomorrow. Wife just came out and said $130 for them to rebuild it, send it in. She crazy.

[budm]

Re: Help with Motor Control Board

That has to be measurement error, as you can see the terminals of the caps are connected to each other with big copper traces.

[R_J]

Re: Help with Motor Control Board

I bet there are bad connections on those caps. scrape some of the paint (about 1/8 in)from the copper trace around the capacitor connections, then resolder them. I can't tell from the picture but it looks like the cap leads have metal gromets and these can cause poor connection to the actual copper traces.

[budm]

Re: Help with Motor Control Board

I was hoping that the connections have already been inspected sine the boards are subjected to heat and Vibrations in these thread mill machine.

[keeney123]

Re: Help with Motor Control Board

BudM how about just soldering a wire between the caps legs to make sure there is not some sort of a bad connection. A voltage reading and a Ohm reading are differences in the meter. Perhaps the Ohms per volt of the meter is acting as a voltage divider with the bad connection of the cap that reads -49 volts and the ohm reading of the meter, by supplying its own current at a low level, can not detect the bad connection. It is a thought, how ever twisted it might be. And Crrose glad your hanging in. That is the only real way to learn this stuff.

[selldoor]

Re: Help with Motor Control Board

Great stuff a few more clues. -hint- its a great balancing trick but you have to keep the wife on side- many repairs fall by the wayside due to not following this rule.

When it was almost there - that is clicking, was the motor connected?
Perhaps try to get to that again without the motor connected and see if there is any voltage at the motor connectors.


The part about bad joints reflects what the repairers said they did as part of the repair.

@budm or anyone who knows- My circuit skills are pathetic I keep looking at this
fairly simple looking set up and just dont see how the voltage at the caps
say 166vdc is reduced down to 24v for the motor when there is no transformer.
Is it the area with the two big resistors that accomplishes this.

[Crrose]

Re: Help with Motor Control Board

Since I have wires soldered to the caps, can I just connect the positive to positive and negative to negative joining the caps together to see what happens? And I have tested and retested them, still get the same results. -49VDC and if I switch leads I get +50VDC on that one cap, and I did confirm I was testing correct wires.

[Crrose]

Re: Help with Motor Control Board

I tested the black red motor wires and it is giving me a reading of 14.4VDC, shouldn't that be reading 24V?

[budm]

Re: Help with Motor Control Board

I would remove the solder around the cap legs that is showing 49V and inspect the pads real close to make sure that the copper pads are not islands and the pads are actually connected to the large traces.

[Crrose]

Re: Help with Motor Control Board

I took it back off to check the cap legs and noticed I had confused one of the rectifier legs with the cap leg so it was not soldered correctly. I fixed it and now get 166.4 on both caps.

[Crrose]

Re: Help with Motor Control Board

I was just testing other diodes and D10 has continuity with a reading of .001 when set on diode mode, where D9 D14 and D16 all have a reading of .612 with no continuity. Sure wish I could find a schematic for this thing.

[keeney123]

Re: Help with Motor Control Board

That has to be measurement error, as you can see the terminals of the caps are connected to each other with big copper traces.

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.

[Crrose]

Re: Help with Motor Control Board

I don't really understand the last.

[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.