# Horizon treadmill - motor control board problem

Joined Apr 4, 2010
2
Hi,

Before I explain my problem, please note that I am not an electronics engineer, but like to tinker - and have a BASIC understading of electronics.

Now onto my problem

I have a Horizon Paragon 2 HRC treadmill with a 013674-DG motor control board. The treadmill lights up as normal, incline function operates fine, BUT belt motor will not start.

I removed the leads to the motor from the control board and connected my multimeter. There is 19v DC at the motor terminals when the treadmill is turned on but not running - when "Start" is pressed on the treadmill, the voltage rises to 20.5V DC. I tested the motor with a 24v DC 15A supply (which I made from an old ATX PC Power supply - thanks instructables.com) and it spins ok, so I'm pretty confident the motor isn't the problem.

I have checked all the diodes in circuit (in situ) and they appear ok (readings one way, open circuit the other - checks one on the diode setting on the multimeter). If I increase the treadmill speed the voltage at the motor terminals doesn't increase (which I presumed it would, to make the motor increase in speed - as the belt motor is rated 180V DC).

Can anyone give me any insight as to what components to check next, or have had a similar problem and found a solution?

I have also noticed, on the board between the two large capacitor are two LED's. The one nearest the motor spade terminals is illuminated (but not at full brightness) when the treadmill is turned on, but not running. When running the LED goes out. The LED nearest the fuse never illuminates.

Thanks for taking the time to read my post

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#### kkazem

Joined Jul 23, 2009
160
Hi,
Since I don't have a schematic for your treadmill, I can only give you general hints and things to do. First and foremost, call the manufacturer and talk to the parts department first, and ask if they can email you a copy of the repair manual or at least the schematic and Bill of Materials, if they can't or won't, then call back and ask the repair department and make sure to talk to a technician--they are often sympathetic with technical people that want to fix their own unit. And, while you have them on the phone, tell them briefly what the problem is and what you've found with the 20V and the diode checks and ask them what they think it might be and if they've seen that problem before (they undoubtably have). If you don't get anywhere with that tack, then go back to the motor control ckt board. This is almost certainly a PWM motor control using either power BJT's, Power Mosfets, Power IGBT's, or a Power Module (the module thing is unlikely). These power devices nearly always fail shorted, and they are all 3-terminal devices. Caution!!! Do Not attempt to repair unless the unit has been unplugged for at least 10 minutes, and even then, be cautious--use your DVM to ensure that the DC power supply voltage is below 5 or 10 volts and of course, only work on it unplugged, not just turned off. There is likely a voltage doubler on the AC making up to 375 VDC for the PWM motor drive, even if no doubler ckt, then about 190 VDC. If it has UL approval, the high-voltage DC supply is supposed to have bleeder resistors to bleed the dc down to below about 50VDC (SELV-safety extra low voltage) after no more than 1 minute, but better safe than dead--always measure after letting it sit for 5 or 10 minutes after unplugging it. Then, check the power switches for the motor control. It will either be a half-bridge (2 power switches) or a full bridge (4 power switches) that likely operate at close to 20KHz to eliminate audible noise in the switching pwm motor controller. This ckt is exactly the same topology as a switching power supply using a full or 1/2 bridge topology, except that the switch load is a motor and not a high-frequency transformer, etc. Although some manufacturers get their semi's house marked to make it hard for anyone else to tell what the real p/n's are, this is not done much these days. If you can get the datasheet on the power switches, you will know if they are MOSFETS, IGBT's, or BJT's and then you may very well be able to identify blown power switches with your DMM using the ohms and/or diode scales, depending on the type of part.
Good luck,
Kamran Kazem

Joined Apr 4, 2010
2
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#### jatinah

Joined Jul 26, 2010
11
Saw your post and wondered if you figured out your motor control board. I know this board, so let me know if you have questions. There is no voltage doubler on this board, and the 20vdc you read on the motor pins, is a dc bias voltage on the DC voltage rail. This rail goes up to 165vdc when the safety relay energizes. This relay will not activate if the kickback diode or driving FET are blown, which is usually the case.....

#### R!f@@

Joined Apr 2, 2009
9,746
Without a schema it is impossible to tell you what to do exactly.

Post pictures of everything. Closeups of circuit boards from all sides and also of whatever labels the tread has.

This will help a alot.

#### JoeJester

Joined Apr 26, 2005
4,390
i need mc60 board circuit diagram
You can certainly draw one from your existing PCB.

#### R!f@@

Joined Apr 2, 2009
9,746

#### gregmurphy0

Joined Oct 28, 2010
6
I have the exact same problem. The Scr also tested ok. If anybody found the problem please let me know. Thanks.

#### R!f@@

Joined Apr 2, 2009
9,746
I have the exact same problem. The Scr also tested ok. If anybody found the problem please let me know. Thanks.
Let u know..just like tht ..huh!

Share something for a change...

#### jatinah

Joined Jul 26, 2010
11
Hi Again.....this particular controller is prone to fail at the Switching FET and the Kickback Diode. Looking at the pic in a previous post, these would be the components standing up, to the rear right of the PCB. The FET would be an IRFP250 and the Diode is most likely the dreaded MOSPEC diode rated at 15A, which shorts, and immediately rips the FET. ;o)
You then also need to check 2 parallel schottky diodes, back-2-back, which are configured in parallel with the current limit resistor next to it. This was an older design of clamping the current sense line to avoid catastrophic failures, but the design was flawed elsewhere ;o)
You have to pull up one end of both diodes, schottky's will read about .160 on a digital meter, unlike a regular silicone diode which reads about .550-.650 on the same diode-scale on the DMM.
Those that would like advanced info on this controller can email me at <snip>

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#### gregmurphy0

Joined Oct 28, 2010
6
I would love to share something but I have just joined the forum and have the exact same problem as CaptainMAD so until something exciting happens in my life, (maybe repairing a treadmill), I haven't much to share that I think would interest anybody. Maybe you have some questions for me?

#### R!f@@

Joined Apr 2, 2009
9,746
Check the power devices for shorts first. Also all the diodes too and post back

#### gregmurphy0

Joined Oct 28, 2010
6
The schottky diodes test ok and the power devices are not short. I can't readthe number of chip U1. At one pin the full voltage is there and another pin is at 19v. Could this be faulty?

#### R!f@@

Joined Apr 2, 2009
9,746
The schottky diodes test ok and the power devices are not short. I can't readthe number of chip U1. At one pin the full voltage is there and another pin is at 19v. Could this be faulty?
Open a new thread and we can go from there.

We cannot continue on another man's thread. Things will get confusing

#### gregmurphy0

Joined Oct 28, 2010
6
First time but I think I have started a new thread.

#### R!f@@

Joined Apr 2, 2009
9,746
First time but I think I have started a new thread.

#### pfiff

Joined Dec 31, 2010
2
Hello,

I have experienced the very same failure on this controller board in my Horizon 5.1T Treadmill. The failure occurred shortly after a power interruption as I was using the treadmill. In my case the MOSPEC U15A60 diode actually blew up and the package is now in pieces. Since it is no longer in the circuit and I assume it was installed in the reverse direction to absorb transients, the fact that the control does not work, indicates the probability that the FET switch is also destroyed. Are there any in-circuit checks that can be made with an ohmmeter to determine the health of this component?

I could not find any direct replacement for the MOSPEC part but found what I believe to be an equivalent made by VISHAY, 15ETX 06 FP which is available from DIGIKEY. The FET Switch is also available from DigiKey. I have not lifted the 2 shottky diodes yet. Does anyone know a number on those? They are in parallel with a current Limit 5 Watt resistor, so cannot be checked in-circuit.

Without a circuit schematic, I am pretty much flying blind here, but, due to the cost of a new controller ($185.00) I am committed to fixing this thing myself. If anyone out there has a schematic or more description of circuit operation, I would appreciate the help! I was looking to replace these parts without taking the two-board stack apart, by just clipping out the old components and soldering in new ones. If anyone has attempted this I would apprecaite info on proper dis- assembly and re-assembly. This forum is valuable for electrically inclined folks who like to fix things themselves rather than pay large sums of cash for a new part or a repair. Thanks in advance for all the info! ...........Pfiff #### pfiff Joined Dec 31, 2010 2 More info on the repair of this control. Horizon was no help whatsoever. They just want to sell control boards for grossly inflated prices. Took apart the board "sandwich" and traced out the Treadmill belt motor driver circuit. In addition to the blown-up MOSPEC U15A60, other suspect parts werethe IRFP250 FET switch, the two shottky diodes (1N5819's), and the S6025L SCR, and its' driver U1 (3SD11 Opto-Isolator, SCR output). Desoldered all the suspect parts and found one of the two shottky diodes shorted, the IRFP250 FET Switch shorted source to drain, the S6025L OK. I didn't bother pulling the 3SD11 as it checked out OK with the ohmeter. Replaced them all and the MOSPEC U15A60 was repllaced with a VISHAY ETX 06 FP. All the parts were available at DIGIKEY and arrived within 5 days. Total parts cost for 5 of each and 10 of the diodes was ~$60.00.

I don't recommend this kind of repair unless you have a good soldering / de-soldering station and a good set of tools for working on small things.

If I didn't have all the do-it-yourself tools, paying $185.00 for a new control board might have been a better deal. Basically reading every last scrap of threads concerning the repair of a similar control board and all the contributing chatter of the various members, convinced me that I could make this repair myself. I am proud to say that the treadmill started up after the repair and has been working smoothly since. Needless to say, in spite of the bad design of the circuit, I have another 4 sets of repair parts in my parts inventory, should it fail again. #### TimQ Joined Feb 11, 2011 1 Had exact same issue as <pfiff> so I took a dive and tried replacing the same chips he mentioned. So far so good. The treadmill is up and running and I'm now following directions in terms of a dedicated 20amp outlet. #### R!f@@ Joined Apr 2, 2009 9,746 More info on the repair of this control. Horizon was no help whatsoever. They just want to sell control boards for grossly inflated prices. Took apart the board "sandwich" and traced out the Treadmill belt motor driver circuit. In addition to the blown-up MOSPEC U15A60, other suspect parts werethe IRFP250 FET switch, the two shottky diodes (1N5819's), and the S6025L SCR, and its' driver U1 (3SD11 Opto-Isolator, SCR output). Desoldered all the suspect parts and found one of the two shottky diodes shorted, the IRFP250 FET Switch shorted source to drain, the S6025L OK. I didn't bother pulling the 3SD11 as it checked out OK with the ohmeter. Replaced them all and the MOSPEC U15A60 was repllaced with a VISHAY ETX 06 FP. All the parts were available at DIGIKEY and arrived within 5 days. Total parts cost for 5 of each and 10 of the diodes was ~$60.00.

I don't recommend this kind of repair unless you have a good soldering / de-soldering station and a good set of tools for working on small things.

If I didn't have all the do-it-yourself tools, paying \$185.00 for a new control board might have been a better deal.

Basically reading every last scrap of threads concerning the repair of a similar control board and all the contributing chatter of the various members, convinced me that I could make this repair myself. I am proud to say that the treadmill started up after the repair and has been working smoothly since. Needless to say, in spite of the bad design of the circuit, I have another 4 sets of repair parts in my parts inventory, should it fail again.

Sorry I did not stumble upon u but you did a damn good job. Congrats