PWM for Treadmill Motor Control Board TD-1600

Discussion in 'The Projects Forum' started by AresROC, Jan 18, 2011.

  1. AresROC

    Thread Starter New Member

    Jan 3, 2011
    19
    1
    Hi All. I am a DIY'er who is kin on electronics. I never received any formal training on electronics, but I learned a great deal because of helpful websites such this one!

    My current project is my LifeSpan 2.25 HP Treadmill, with a motor control board TD-1600N. I have spent the last 3 months troubleshooting it, and now I am stuck, so hopefully someone will be kind enough to point me at the right direction.

    I have contacted the manufacture for technical support, but to no avail. They won't provide repair manual/schematics. They just want to sell a new board at outrages amounts of money and get you to buy a new belt while at it. I figured I could do better by fixing it myself, all the while learning about electronics which I enjoy greatly. :cool:

    I believe I put too much load on the board by not lubricating the belt properly, and burned a transistor/IC somewhere. It was working fine one day. I turn off the AC switch on the treadmill each time, thinking that would preserve the capacitors. The next time I turned on the AC switch, the treadmill turns on properly, but when I start the motor, it won't turn.

    I tested the DC motor with 12 volt, and it works. I traced the problem to the main motor's relay, which is not engaging with a "click" sound. I tested the 12v relay's protection diode, and it has 16v going across it when the motor is supposed to turn. Thinking it must be a faulty relay, I replaced it with a Panasonic unit. Relay still won't engage. The relays on the elevation up/down motor works fine, however.

    After that it was a wild chase. I have replaced:
    3 Relay protection diodes
    3 Opto Coupler / Opto Isolators
    a 2TY PNP Transistor with a S8550

    I traced the board and drew some *ugly/sorry* schematics on Visio. I even went as far as making my own daughter board for the main motor relay to engage AC if 16 volt is detected across the protection diode. The daughter board did engage the relay and turned on the DC motor, but it churned out like 160 volts and the motor went 100 MPH. :eek: Not very helpful unless you are the 6 million dollar man!

    So my latest wild guess is the PWM. On the picture below you can see the red arrow pointing at a 14-pin IC with its markings scratched off by the manufacturer. I wonder if that is the cause, and, what I can replace it with? Any suggestions greatly appreciated! :) (It is the "?" in the schematic, and I think "CTRL" goes up to the treadmill's control panel)

    [​IMG]
    [​IMG]
    [​IMG]

    -AresROC
     
    Last edited: Jan 18, 2011
    treadmillarmen likes this.
  2. AresROC

    Thread Starter New Member

    Jan 3, 2011
    19
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    So I saw some PWMs need to be programmed... is it true? I suppose that would rule out fixing it DIY.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    Before we can make a guess at what that IC is, we'd need to know what all it's connected to. You're going to have to trace out the connections on the board - and to the off-board controls, I'm afraid.

    If it's a microcontroller IC, it'll have to be programmed.

    However, it might be a dedicated PWM controller IC. Those wouldn't require programming, but you'd need the right replacement. There are a LOT of such controllers on the market. Yours is in a 14-pin DIP package; I don't recall of any offhand in that configuration - the DIP versions I've been dealing with are 8, 16 and 18 pin.
     
    Last edited: Jan 20, 2011
  4. AresROC

    Thread Starter New Member

    Jan 3, 2011
    19
    1
    Thanks!! I am unstuck with the hints you provided! I made a new schematic with Fritzing and traced to a daughter-board with a 16-pin IC. The interesting thing is the board is wrapped in a shroud:
    [​IMG]

    Nevertheless I will try to take it apart and take a peek.

    My schematic (still very ugly) with the original 14-pin IC is here:
    [​IMG]
    still very much a work in progress...

    -AresROC
     
  5. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    I doubt the IC marked out in the first photo is the problem.

    It seems the 'brain' is that daughter-board, and something on it may be faulty.

    The problem is, that isn't a plastic case, it's a conformal epoxy coating, attempting to remove it will essentially destroy the board, or remove critical markings at the least. That's the manufacturer's way of saying "No user-serviceable parts inside, and this time, WE MEAN IT". Also prevents reverse-engineering by competitors.
     
  6. AresROC

    Thread Starter New Member

    Jan 3, 2011
    19
    1
    Thanks for the info!!! Yep. It is epoxy coating. No way to service it. :mad:

    I contacted ASTAR, the manufacture of the board. They told me they don't have any in stock. The minimum quantity to start a production run is 300!!!

    But I was once told by a wise man: "If there is a will, there is a way!".

    That got me thinking, since I can engage the motor via my add-on board, if I can just control the speed of the motor, I am good to go. The treadmill's control interface is still turning the belt on and off, and the safety disconnect key is still working.

    Question is, would it be reasonable to build a DC Motor control board for USD $200 or less? I have many of the spare parts already (rectifiers, IGBT transistor, etc), or perhaps I should just attach a PWM to the motor power circuit somehow.

    There are also two transformers mounted to the treadmill's frame, ±24v for the AC height motor, and 12v for the isolated circuits, if memory serves. They might come in handy.
     
  7. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    Let's step back a minute.

    In your first post, in the top photo, do you see those two heat sinks just to the right of the daughterboard and just above the DOWN relay?

    I suspect that the 3-legged critters attached to the heat sinks are either MOSFETs or SCRs.

    Can you read the part numbers on them? Can you unsolder and remove them without destroying the board?

    What I'm thinking is that the controller might be what is known as a synchronous buck DC-DC converter; and that the MOSFETs/SCRs may have become damaged. If the high-side MOSFET were stuck ON (which is a frequent failure mode for MOSFETs; source shorted to the gate) then your treadmill would run lickety-split.
     
  8. AresROC

    Thread Starter New Member

    Jan 3, 2011
    19
    1
    Thanks SgtWookie, I think I will try to take it apart and take a look. They are identified as IC1 and IC2 on the board. IC1 is a L78xx 15volt voltage regulator. (Sorry I am not familiar with SCRs and even MOSFETs). IC2 is hidden behind the heat sink, so I would have to take out IC1 as soon as I can.

    I gave up on "Fritzing" because I was too lazy to draw my own bridge rectifiers after I drew the optocoupler & a few others. I went back to TinyCad and drew as much and as accurate as I can around IC1 & IC2. The PDF is attached.
    [​IMG]

    When the circuit powers up, LED1 and LED2 lids up, and stays on.
    Also, there is a transistor (TO-92) looking item Q10, but it has its markings scratched off...
     
    • PWM.pdf
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  9. AresROC

    Thread Starter New Member

    Jan 3, 2011
    19
    1
    I successfully took out IC2. It's a L7915CV -15v Voltage regulator. :cool:
     
  10. AresROC

    Thread Starter New Member

    Jan 3, 2011
    19
    1
    Finally made progress today!!! :D I took off a couple components and tested them, replaced them, and the Motor Relay finally engaged on it's own!!!

    So there is hope, just when I thought I am done with this project...

    From the circuit I draw above, I figured it seems to me the IGBT is where the speed is controlled by, so I started by inspecting the components from it back to where the source of the problem is.

    Since I don't know how to test the IGBT, I started by removing the unknown component Q10 (TO-92 Package) first. I tested it with DMM's diode mode:

    Pin 1 -> Pin 2 = 845
    Pin 3 -> Pin 2 = 830

    There are no other conductivities, except Pin 1 & Pin 3 is very weird.

    If I engage Pin1 to Pin2 first, then Pin1 -> Pin3 works!
    Pin3 -> Pin1 sometimes conduct, sometimes not... maybe this Q10 is a bad transistor perhaps? Since it most closely resembles a PNP transistor to me, I replaced it with a PNP transistor. There are no other Q## named components on the board, so I am not sure if it is a transistor... another weird thing is there is a capacitor across Pin3 & Pin2...

    I plugged everything in after the soldering, no luck. No smokes either. :rolleyes:

    Next up, the IGBT itself. The factory IGBT is a Toshiba GT60M303. I was not able to find a direct replacement anywhere, so I got a ST GW30N90D instead. Finally, I got some kind of a response out of it!

    When the DC motor is connected to the board, I heard some clicking noise coming from somewhere, and I see LED3 flashing! I powered the treadmill off, unplugged one of the leads to the DC motor, and power it back on. Now the LED3 has a solid green light! Even better, I can hear the main motor relay engage finally!

    Sorry about my long ramblings, this is the only response I have got from the circuit since this project commenced several months ago!

    Before I can proceed any further in repairing this motor control board, I would like to hear your takes on what Q10 actually is.

    And whether the IGBT I have now is a suitable replacement, or a better one can be found.

    Most importantly, I hope this can help someone in the future troubleshoot the DC Motor Control board; and hopefully I can get mine to work eventually! :D
     
  11. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    From your tests, Q10 seems to be a BJT (standard transistor). NPN or PNP isn't for sure, which color leads were on which pins when you got the 0.8v values?

    If the main relay and light come on, is there a problem in the power supply to the motor, or does this board handle everything?
     
  12. AresROC

    Thread Starter New Member

    Jan 3, 2011
    19
    1
    Pin 1 & Pin 3 had (+) red leads, and Pin 2 had (-) black lead.

    Well, the PNP transistor S8550 I put in place of Q10 didn't work. But when I put original Q10 back in place, the treadmill worked! Finally!

    Apparently the board is designed not to function without a working IGBT. Funny how I thought since the IGBT is made by Toshiba, it's probably a quality component, and since the relay is not sending power down there, I neglected to check on it. Lesson learned.

    This IGBT is critical, it can take on 60~120 Amps of DC power. I must have burned it out with the treadmill.

    Luckily, I found several exact IGBTs in stock. I plan on mounting the new one on an isolated heat sink, place it next to the motor for some cooling air, and see how long that will last! :D

    UPDATED TinyCad:
     
    • PWM.pdf
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  13. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Glad you got it working!

    What was the number on Q10 in the event the soldering heat shocked into working just for a while?
     
  14. AresROC

    Thread Starter New Member

    Jan 3, 2011
    19
    1
    It was just the IGBT wasn't working. I believe Q10 worked the entire time. Just the PNP transistor I replaced Q10 with was causing a clicking noise for some reason.

    The treadmill works now, but the motor seems to lack power. Since I replaced the SMT transistors 2TY & J3Y with TO-92 "equivalents", the voltages have dropped across the line. I am now looking for 2TY & J3Y SMT's... should have gotten the SOT-23's instead originally... :(
     
  15. AresROC

    Thread Starter New Member

    Jan 3, 2011
    19
    1
    Update: Also found out a relay protection diode was blown shorted. Most likely it is the main motor relay diode. That probably burned out the IGBT as well.
     
  16. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
    141
    Nice job, AresROC! This is one of the things I love about AAC -- an interested and enthusiastic person can come get help and solve a tough problem.

    Besides sticking the replacement part(s) inside the device, I suggest you also document what you learned in detail, then print it out, put it in a plastic bag, and put the bag inside the device too. The parts are relatively easy to get, but you've got a lot of hard-won knowledge you don't want to lose. If your brain is even slightly like my Alzheimer's-ridden one, you'll forget all the details in short order. :p
     
  17. Ray190te

    New Member

    May 7, 2011
    1
    0
    Hi AresROC

    Glad you got it sorted, I have a similar issue with a TD-300 and was wondering if you managed to get a value for CNR1 as mine is turned into smoke?

    Regards
     
  18. aztlancar-audio

    New Member

    Jan 30, 2013
    1
    1
    algien abla espanish


    grasias amigos yo tengo el mismo problema y esta informacion es de gran ayuda
     
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  19. FurzNZ

    New Member

    Jun 13, 2013
    1
    0
    Hi guys.
    I have the 230V version of this control board. Is anyone able to please tell me the value of CNR1. Mine has had a massive fail and blown a hole right throught it, so I can't read the values.
    Thank you!!!!
     
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