MC2100 Rev B - Issues (Treadmill Main Board)

Thread Starter

interactive

Joined Dec 18, 2020
7
MC2100 RevB- I have aquired 3 of these boards (dang Proform) over time and now at a stage that all 3 have their own weird issues. I tried replacing MOSFET IR260N on two of the boards in hopes of fixing it, as I don't have a bench setup to diagnose exactly what could be the issue, I have switched the big fat cap between cards. Latest symptoms are following.

Card A - Original (works for a little bit specially if heatsink not grounded, if heatsink is grounded its a Scary - full speed Run Away), If heatsink is all tightened down its a run away off the bat. (has a good chance IMHO)
Card B- Worked the longest but now even after replacing the MOSFET a solid red led after and start doesn't do anything remains solid.
Card C - Works but is temperamental on speeds and such, so cannot have confidence specially with kids/mom as it could be dangerous. this is also the card on which there is and auxiliary power transformer on the board.

I am pretty handy and engineer by profession and have had my Kitchen Aid 48" running successfully over the years after a lot of capacitor/Relay changes on the mainboard, similarly have kept Samsung washer/Dryers functional, my carrier 5ton ac units running and proud of being the handyman I am credit to these forums. the idea is I can tinker at a decent level and have tools etc to go after it including a haako iron, but I am NOT an expert at reading circuits or knowledge of individual components function on the boards etc. I want to fix above one or all myself and need your expertise, if you can put me on a right path that would be awesome.

Alternatively I can donate a card (you pay shipping) to an expert who can make one of mine run effectively :)and you can build your PWM Circuit and digitally controlled sander or a lathe controller (came across those fantastic articles while researching my issue).

Sorry for a long post guys.
 

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MaxHeadRoom

Joined Jul 18, 2013
21,964
There are a couple of reasons the LED does not flash, one is the SCR does not switch on, or the motor circuit is open.
I have PWM boards made up for the independent use supplying the PWM command.
I see two are using the off-board supply transformer!
Max.
 

Thread Starter

interactive

Joined Dec 18, 2020
7
There are a couple of reasons the LED does not flash, one is the SCR does not switch on, or the motor circuit is open.
I have PWM boards made up for the independent use supplying the PWM command.
I see two are using the off-board supply transformer!
Max.
Yes and these all have worked for me at some point in time. and are the Card (b) Card(a) and Card(c) per my post. Can you point me on how to diagnose SCR or motor circuit further.
 

MaxHeadRoom

Joined Jul 18, 2013
21,964
Card A: definately sounds like a defective thermal insulator?
Card B: See if output of the SCR rises up to 200v, if not could be the SCR itself.
Card C: Check speed sensor for correct spacing etc.
Do you have the schematic posted here earlier?
Max.
 

Thread Starter

interactive

Joined Dec 18, 2020
7
Card A: definately sounds like a defective thermal insulator?
Card B: See if output of the SCR rises up to 200v, if not could be the SCR itself.
Card C: Check speed sensor for correct spacing etc.
Do you have the schematic posted here earlier?
Max.
Hi Max, I have the following. Can you please point me to the thermal insulator and SCR on the board.
 

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MaxHeadRoom

Joined Jul 18, 2013
21,964
Thinking about it a little more, I assume what you meant was if you connect a GND conductor to the HS, the motor takes off?
if so, Measure the voltage between the H.Sink and the GND conductor. AC or DC?
Also ensure the L1 and Neutral are correct at the AC input terminals.
There are two supplies on the board, the HV is non-isolated and the LV is referenced to GND (HS) via the R1 10Ω res.
Max.
 

Thread Starter

interactive

Joined Dec 18, 2020
7
Thinking about it a little more, I assume what you meant was if you connect a GND conductor to the HS, the motor takes off?
if so, Measure the voltage between the H.Sink and the GND conductor. AC or DC?
Also ensure the L1 and Neutral are correct at the AC input terminals.
There are two supplies on the board, the HV is non-isolated and the LV is referenced to GND (HS) via the R1 10Ω res.
Max.
I meant the HS being screwed into the frame compared to keeping it on a cardboard and testing it, whether we screw in the green wire or not the card is supposed to be grounded with the heatsink as there is a track on the backside of the card that touches heatsink. I will measure the voltage between heatsink and treadmill frame as well as what you mentioned and report back. L1/Neutral seem to be correct.
 

MaxHeadRoom

Joined Jul 18, 2013
21,964
the card is supposed to be grounded with the heatsink as there is a track on the backside of the card that touches heatsink.
If you are talking about the small thin foil strip that runs along the edge, this is just for the ground reference for the isolated 12v-15vdc supply.
The small green wire connected to the heatsink does the same thing.
It should not be connected to any of the HV circuits.
Max.
 

Thread Starter

interactive

Joined Dec 18, 2020
7
https://forum.allaboutcircuits.com/...eadmill-main-board.175114/reply?quote=1581297
I meant the HS being screwed into the frame compared to keeping it on a cardboard and testing it, whether we screw in the green wire or not the card is supposed to be grounded with the heatsink as there is a track on the backside of the card that touches heatsink. I will measure the voltage between heatsink and treadmill frame as well as what you mentioned and report back. L1/Neutral seem to be correct.
Max
If you are talking about the small thin foil strip that runs along the edge, this is just for the ground reference for the isolated 12v-15vdc supply.
The small green wire connected to the heatsink does the same thing.
It should not be connected to any of the HV circuits.
Yes I meant that foil, I posted a pic to show how its connected and the metal side on a card board for now the other side of the HS rests on a plastic body.

Card A - 64v AC between treadmill body and HS when HS is on a cardboard and treadmill switched on but not started
Card B - 10v AC between treadmill body and HS when HS is on a cardboard and treadmill switched on but not started
 

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MaxHeadRoom

Joined Jul 18, 2013
21,964
By T.M. body, I assume you mean the metal frame?
It is often normal to see a AC leakage voltage when using a Hi impedance meter.
If testing the track motor circuit, I would disconnect incline motor, tach, INS header. just leave the power, CB and motor, and maybe HD2 and of course the transformer connections if off board..
Max.
 

Thread Starter

interactive

Joined Dec 18, 2020
7
By T.M. body, I assume you mean the metal frame?
It is often normal to see a AC leakage voltage when using a Hi impedance meter.
If testing the track motor circuit, I would disconnect incline motor, tach, INS header. just leave the power, CB and motor, and maybe HD2 and of course the transformer connections if off board..
Max.
Hi Max, I got back to it yesterday, I think I made a noob mistake of not having MOSFET 260N thermally insulated and screwed it down to the HS in last few tries so Drain was grounded, MOSFET was shot so replaced it again and it seems to be working in 1 minute test I did without load, still worried to get on it yet though and plan on changing the 1500uf 200v cap. as it shows 1200uf while testing. what are other things that could cause a MOSFET failure, want to ensure I fix the root cause before calling it a successful fix?
 

MaxHeadRoom

Joined Jul 18, 2013
21,964
Basically what you have already mentioned, there is quite a bit of protection as regards overload etc, I add some thermal compound when mounting also.
Max.
 

Thread Starter

interactive

Joined Dec 18, 2020
7
Basically what you have already mentioned, there is quite a bit of protection as regards overload etc, I add some thermal compound when mounting also.
Max.
Ok running the treadmill without load it ran ok multiple times and then after starting to walk on it runaway situation in 2 minutes, burnt smell, likely the MOSFET is shot again. I am about ready to give up on this but curious if anyone has an idea on what is causing this. Is it possible MOSFETS are bad quality, I was trying to save on shipping time when I ordered those in Dec from Amazon (non descript ones) instead of mouser/digikey. Its tested as attached before putting in.
 

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MaxHeadRoom

Joined Jul 18, 2013
21,964
Just ensure you have no (or little) voltage on the M+ terminal when the motor is at idle.
When a run command is given, the micro operates the mosfet, at the same time, it ramps up the +V (M+) via the SCR S2402.
Max.
 
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