Sorry for my last (too long) reply. :) However, I am happy to report that I finally found the issue which was a short in the rectifier! For the DCMD67 this short is only a problem when the relay is closed. Otherwise there is a 33k resistor which limits the current! Just for your info: you can test the DCMD67 motor circuit completely stand-alone with the 7-pin connector. This connector gives you +12 V at pin 0 (rightmost) and GND at pin 1. In order to enable the board you have then to put +5V const. at pin 5 (safety magnet) and finally ground at pin 4 to enable the relay (START). Finally you can use the pins 3 & 4 with pulses towards GND to increase / decrease the DC output voltage. This test works fine with a regular bulb connected to the M+ M- output connectors. Cheers! Alex'
Hi Alex, No worries. Glad you found your problem. Well done. You’re talking about the small round rectifier right? Nice info on testing the board. Cheers Craig
Craig: Thank you very much again for all the time and effort you put into these videos. They help more than you could imagine. Thanks for taking time to respond to and answer questions. You answered my question about the safety relay, it helps alot. In responce to one of the comments about the board design, I can't help but wonder if a lot of the board failures can be attributed to the failure of owners and users to properly maintain their treadmills. I can imagine that the current draw goes up significantly if the boards and belts are not regularly cleaned and waxed and/or replaced as required by the mfg. I've run across a few of the control units that stop the treadmill from operating with a "maintenance required" warning, but once people find the work around on the internet, it's back in operation with nothing else done. Please continue your wonderful videos. I do appreciate your efforts. Stay safe and healthy, and all the best to you!!!!!
Hi Andre, No worries mate - the feedback and questions give me good points to address in the videos. On the treadmills we get here in SA, i.e. single phase simple speed and sometimes incline control, there is very little that can go wrong mechanically. The machines that I have actually seen, even though they stood out in the elements, did not even require re-greasing or anything like that. The issues I have found all relate to component failure. From the little bit of back of the cigarette box calculations I bothered to do - the hard working components are sized borderline i.e. they can only just carry the current required, high RDS on values etc. The other problem is that whoever did the board design - did not follow the manufacturers recommendations i.e. heat pads, grounding rings etc. These are either very basic mistakes or deliberate. From the few internet searches I have made as well as some of the questions asked here - these issues seem to pop up world wide. You chaps up there in Canada seem to have a much better product. You would be right in saying that without mechanical love, things would get harder to drive and current draw would be higher so temperatures etc would go up. But as per my comment above - these things seem to be deliberately borderline. Just out of curiosity, I did a quick search for a replacement board cost - USD130 or ZAR1950 - the treadmill only costs ZAR10000, so the board is 20% of the cost. That's a fair wack of money here in SA. Obviously this excludes shipping costs. The cost to me or anyone here in SA buying the replacement parts FET ~ ZAR75, TNY266 ~ ZAR30, Fly-back diode ~ ZAR25, Opto coupler ~ ZAR8 delivery from RS ~ ZAR100. These prices are for better components than were part of the original design. And - I don't charge anything for my time - only a case of beer and the cost of the replacement components and delivery. I will do mate. Many thanks once again to you guys that watch and comment. That is what makes it worthwhile. If you haven't seen it yet - check out the back to basics series. I'm actually using each circuit type to build up an actual product . Cheers Craig
Hi, your videos are very informative, thank you. I have a similar board: DCMD76. The component fried below the Opto Coupler which you added. Its beyond recognition. Please advise what component/code is on yours.(8pin) Much appreciated
Hi Ghalid, Many thanks for the kind words. The offline switcher is actually a 7 pin DIP. Part number is TNY-266. If the TNY is blown, there is a good chance the little round rectifier above it is blown too. Cheers Craig
I follow your channel with interest and have gained a lot of knowledge from your different projects as well as your back to basics sessions. Keep up your great work! I'm wondering if there is a design flaw in these trojan boards as there appears to be a lot of dead treadmills around?
Hi John, Many thanks for the kind words. From looking at the board layout and the actual circuit design - they have not put a lot of effort into it. A small case would be that they should have put a copper pad with a few via's for heat transfer under the offline switcher. I suspect that it gets very hot and gives up the ghost. They could also have designed in a whole lot more protect the rectifier, the FET and the fly back diode. While the cost of these components varies from ZAR30 - ZAR75 per component may not be much, I suspect that the labor cost of getting a electronic tech/engineer to fix it would be expensive. I'm not sure what a repaired board would cost - so it may be worthwhile. Although, I did get a board that a "tech" tried to repair and the damage to the circuit traces was horrendous. So maybe repair is a dying art. I have not come across many of these boards to repair though. It started with a work colleagues board which I made a series about and then viewers started sending their boards in - which I appreciate as it gives me material for the videos. I have had a few comments about the board form people all over, but most cases I would not classify as board problems, more like contact problems from the connectors etc. I'm glad you are enjoying the back to basics series. There are more videos coming on that. I am actually using each building block as a step to the next concept. At the end of it all I use each building block to actually design a product that will be sold commercially, but I will release the design's PCB layout, MCU code etc as open source. That way, people can build on it and modify it to suit their own purpose. I put the product together for a friend who has a solar setup. So we monitor his battery bank voltage and switch off certain house circuits based on user defined settings. There are things like opto couplers, micro controllers, relays, LCD's, Keypads etc that all come together to make it work. Ideally, each one of the building blocks from the series will come together and give you guys ideas on how to use them. Cheers Craig
Amazing analysis, congratulations! I'm wondering if you can help me out with the analysis of my DCMD67 problem: The treadmill (including this board) is initially working fine when it gets powered on. There is no error code on the screen. However, when rotation shall start the fuse always blows up. I observe the same behaviour when both motors are disconnected. Any idea where to look first in this case? I have already searched around for a while to find any schematic for the DCMD67 but without success so far. Likewise it would be really helpful to understand how to control the interface of this board for further testing. In case you can help please let me know if you have some PayPal account for a donation. Thanks a lot!
Hi Alexander, If the fuse only blows when you try to start the circuit - you have a short in the motor drive circuit. It can only be a handful of components. You should check the FET and it’s associated driving circuit as well as the fly back diode. Let us know how you get along. Cheers Craig
@@foulkesbrau3085 Hi Craig! Thanks a lot for your fast reply! Actually this makes sense for me to analyze the motor drive circuit. By chance I found your video #42 where you did exactly this repair for the DCMD57P. Even though I have the DCMD67 I think the approach should be nearly identical, right? So referring to DCMD67 now, I think I have to analyze the FET (U18), the flyback diode (U11), the driver (U9) and this discharge diode (D19). However, when looking at these components I found that on the DCMD67 the (D19) is not in place (also R64 is missing)!? This can also be observed in this video #62. Do you have an idea why this is the case? Finally I wanted to ask you about the schematic for the DCMD57P or DCMD67 again: In the video #42 you stated at the beginning that you reverse-engineered most of the board. Do you have a more detailed schematic than the hand-drawn one that you could share? Thanks so much & Cheers Alex'
Hi Alex, The approach is identical for all boards. Work your way back from the thing you’re trying to drive. You would need to look at the data sheet for the driver ic. I suspect that they found out they didn’t need the snubber circuit for the gate of the FET. Perhaps the driver ic they used has internal discharge etc for the gate. I have not updated the hand drawn circuit unfortunately. I only drew enough to give an idea of the main parts as I’ve never come across a board that had issues with the controls other than the main drive. Only a pleasure. Cheers Craig
@@foulkesbrau3085 Hi Craig, Over the holidays I have been trying to finally resolve the issue with my board (DCMD67). Unfortunately the whole failure is still a riddle for me: 1. I completely removed the power FET and I do not connect any load to the output of the board (I refer to the main output here which is the one driving the belt). 2. In this setup I can power on the board normally and everything is looking fine for me. E.g. the power indicator LED is on and I can measure the +12V at pin 0 (rightmost) of the 7-pin connector. I do also connect the +5V DC response to the 7-pin connector to emulate the control panel (c.f. ua-cam.com/video/vUH5Tl-q_Xo/v-deo.html): 3. However, at the output of the rectifier (the one at the top of the board) I do measure only approx. 190 V DC, which is far too low in my opinion. At the same time I observe that there is a significant voltage drop at the 33k resistor at the (+) AC input of the rectifier. This is also curious since in my opinion the relay, which is in parallel to the 33k, should close that contact fully during operation. 4. Finally, when I close the relay manually via a wire (bridging the 33k resistor) the board's fuse (including the one in the fuse box of the house @ 16A!) blows. 5. For me it is tough to draw the right conclusions from these observations, but I give it a try: (A) The low output voltage at the rectifier is OK because the relay is closed only when rotation shall start. So it is OK to manually close the relay to power the rectifier. Thus there is a problem with the large cap (or its parallel companion) with a short at a certain voltage. (B) There is an issue with the rectifier itself (some short inside). 6. Unfortunately option (A) is not even making sense to me, its just rough guessing. In option (B) everything would make a bit more sense but I would be wondering about the fact that the fuse holds in that scenario and that there is such a high voltage drop at the relay. In general for my understand it would be very helpful to understand (Q1) if I should expect to have a closed relay already after power on and (Q2) the circuitry which switches the relay. Thanks a lot & BR Alex'
Hi there I have a trojan treadmill with a DCMD67 board the middle board in your video when I press start on the keyboard it counts down then I hear the relay click in but the motor doesn't turn and the error 1 pops up on the screen
Hi Sir I have the same problem with my threadmill as Justin above. I have tested the motor and the sensor and they are working fine. When looking at the board the green diode (FDC+) lights up fine but the yellow diode (written fast/slow on the board) lights up in two series of blips. Do you have any idea what could this indicate? Thanks for your help. Arnaud from Mauritius
Hi there, Have you tested everything in the motor drive circuit? By this I mean the FET, the fly back diode, the FET driver with its associated circuitry? If the motor is good and it doesn’t turn - then I’m pretty sure it’s the FET. Cheers Craig
Hi there, It is very difficult to tell. What error codes do you get on the master panel? If the motor starts and stops shortly - you have a problem with the speed sensor or the belt alignment. I would start to look at those parts of the circuit. Cheers Craig
Well, E01 means the main board is not seeing the sensor. You need to trace the wires. Do you measure the speed sensor where it comes into the main board? Are the wires broken? Measure is the only way.
Hi, Have you tried to google the error? When I do, It tells me that you might have a faulty/loose connection between the board under the motor cover and the console. Cheers Craig
Sorry for my last (too long) reply. :)
However, I am happy to report that I finally found the issue which was a short in the rectifier!
For the DCMD67 this short is only a problem when the relay is closed. Otherwise there is a 33k resistor which limits the current!
Just for your info: you can test the DCMD67 motor circuit completely stand-alone with the 7-pin connector. This connector gives you +12 V at pin 0 (rightmost) and GND at pin 1. In order to enable the board you have then to put +5V const. at pin 5 (safety magnet) and finally ground at pin 4 to enable the relay (START). Finally you can use the pins 3 & 4 with pulses towards GND to increase / decrease the DC output voltage. This test works fine with a regular bulb connected to the M+ M- output connectors.
Cheers!
Alex'
Hi Alex,
No worries. Glad you found your problem. Well done.
You’re talking about the small round rectifier right?
Nice info on testing the board.
Cheers
Craig
@@foulkesbrau3085 Hi Greg, thanks! Actually I referred to the large rectifier at the right-top of the board. This one was shortened! Cheers Alex'
Craig: Thank you very much again for all the time and effort you put into these videos. They help more than you could imagine. Thanks for taking time to respond to and answer questions. You answered my question about the safety relay, it helps alot. In responce to one of the comments about the board design, I can't help but wonder if a lot of the board failures can be attributed to the failure of owners and users to properly maintain their treadmills. I can imagine that the current draw goes up significantly if the boards and belts are not regularly cleaned and waxed and/or replaced as required by the mfg. I've run across a few of the control units that stop the treadmill from operating with a "maintenance required" warning, but once people find the work around on the internet, it's back in operation with nothing else done. Please continue your wonderful videos. I do appreciate your efforts. Stay safe and healthy, and all the best to you!!!!!
Hi Andre,
No worries mate - the feedback and questions give me good points to address in the videos.
On the treadmills we get here in SA, i.e. single phase simple speed and sometimes incline control, there is very little that can go wrong mechanically. The machines that I have actually seen, even though they stood out in the elements, did not even require re-greasing or anything like that.
The issues I have found all relate to component failure. From the little bit of back of the cigarette box calculations I bothered to do - the hard working components are sized borderline i.e. they can only just carry the current required, high RDS on values etc. The other problem is that whoever did the board design - did not follow the manufacturers recommendations i.e. heat pads, grounding rings etc. These are either very basic mistakes or deliberate. From the few internet searches I have made as well as some of the questions asked here - these issues seem to pop up world wide. You chaps up there in Canada seem to have a much better product.
You would be right in saying that without mechanical love, things would get harder to drive and current draw would be higher so temperatures etc would go up. But as per my comment above - these things seem to be deliberately borderline. Just out of curiosity, I did a quick search for a replacement board cost - USD130 or ZAR1950 - the treadmill only costs ZAR10000, so the board is 20% of the cost. That's a fair wack of money here in SA. Obviously this excludes shipping costs. The cost to me or anyone here in SA buying the replacement parts FET ~ ZAR75, TNY266 ~ ZAR30, Fly-back diode ~ ZAR25, Opto coupler ~ ZAR8 delivery from RS ~ ZAR100. These prices are for better components than were part of the original design. And - I don't charge anything for my time - only a case of beer and the cost of the replacement components and delivery.
I will do mate. Many thanks once again to you guys that watch and comment. That is what makes it worthwhile. If you haven't seen it yet - check out the back to basics series. I'm actually using each circuit type to build up an actual product .
Cheers
Craig
Are you in cape town
Hi, your videos are very informative, thank you. I have a similar board: DCMD76. The component fried below the Opto Coupler which you added. Its beyond recognition. Please advise what component/code is on yours.(8pin) Much appreciated
Hi Ghalid,
Many thanks for the kind words. The offline switcher is actually a 7 pin DIP. Part number is TNY-266. If the TNY is blown, there is a good chance the little round rectifier above it is blown too.
Cheers
Craig
I follow your channel with interest and have gained a lot of knowledge from your different projects as well as your back to basics sessions. Keep up your great work!
I'm wondering if there is a design flaw in these trojan boards as there appears to be a lot of dead treadmills around?
Hi John,
Many thanks for the kind words.
From looking at the board layout and the actual circuit design - they have not put a lot of effort into it. A small case would be that they should have put a copper pad with a few via's for heat transfer under the offline switcher. I suspect that it gets very hot and gives up the ghost. They could also have designed in a whole lot more protect the rectifier, the FET and the fly back diode. While the cost of these components varies from ZAR30 - ZAR75 per component may not be much, I suspect that the labor cost of getting a electronic tech/engineer to fix it would be expensive. I'm not sure what a repaired board would cost - so it may be worthwhile. Although, I did get a board that a "tech" tried to repair and the damage to the circuit traces was horrendous. So maybe repair is a dying art.
I have not come across many of these boards to repair though. It started with a work colleagues board which I made a series about and then viewers started sending their boards in - which I appreciate as it gives me material for the videos. I have had a few comments about the board form people all over, but most cases I would not classify as board problems, more like contact problems from the connectors etc.
I'm glad you are enjoying the back to basics series. There are more videos coming on that. I am actually using each building block as a step to the next concept. At the end of it all I use each building block to actually design a product that will be sold commercially, but I will release the design's PCB layout, MCU code etc as open source. That way, people can build on it and modify it to suit their own purpose. I put the product together for a friend who has a solar setup. So we monitor his battery bank voltage and switch off certain house circuits based on user defined settings. There are things like opto couplers, micro controllers, relays, LCD's, Keypads etc that all come together to make it work. Ideally, each one of the building blocks from the series will come together and give you guys ideas on how to use them.
Cheers
Craig
Amazing analysis, congratulations!
I'm wondering if you can help me out with the analysis of my DCMD67 problem:
The treadmill (including this board) is initially working fine when it gets powered on. There is no error code on the screen. However, when rotation shall start the fuse always blows up. I observe the same behaviour when both motors are disconnected.
Any idea where to look first in this case?
I have already searched around for a while to find any schematic for the DCMD67 but without success so far. Likewise it would be really helpful to understand how to control the interface of this board for further testing.
In case you can help please let me know if you have some PayPal account for a donation.
Thanks a lot!
Hi Alexander,
If the fuse only blows when you try to start the circuit - you have a short in the motor drive circuit. It can only be a handful of components. You should check the FET and it’s associated driving circuit as well as the fly back diode.
Let us know how you get along.
Cheers
Craig
@@foulkesbrau3085
Hi Craig!
Thanks a lot for your fast reply!
Actually this makes sense for me to analyze the motor drive circuit. By chance I found your video #42 where you did exactly this repair for the DCMD57P. Even though I have the DCMD67 I think the approach should be nearly identical, right?
So referring to DCMD67 now, I think I have to analyze the FET (U18), the flyback diode (U11), the driver (U9) and this discharge diode (D19). However, when looking at these components I found that on the DCMD67 the (D19) is not in place (also R64 is missing)!? This can also be observed in this video #62. Do you have an idea why this is the case?
Finally I wanted to ask you about the schematic for the DCMD57P or DCMD67 again: In the video #42 you stated at the beginning that you reverse-engineered most of the board. Do you have a more detailed schematic than the hand-drawn one that you could share?
Thanks so much & Cheers
Alex'
Hi Alex,
The approach is identical for all boards. Work your way back from the thing you’re trying to drive.
You would need to look at the data sheet for the driver ic. I suspect that they found out they didn’t need the snubber circuit for the gate of the FET. Perhaps the driver ic they used has internal discharge etc for the gate.
I have not updated the hand drawn circuit unfortunately. I only drew enough to give an idea of the main parts as I’ve never come across a board that had issues with the controls other than the main drive.
Only a pleasure.
Cheers
Craig
@@foulkesbrau3085 Hi Craig,
Over the holidays I have been trying to finally resolve the issue with my board (DCMD67). Unfortunately the whole failure is still a riddle for me:
1. I completely removed the power FET and I do not connect any load to the output of the board (I refer to the main output here which is the one driving the belt).
2. In this setup I can power on the board normally and everything is looking fine for me. E.g. the power indicator LED is on and I can measure the +12V at pin 0 (rightmost) of the 7-pin connector. I do also connect the +5V DC response to the 7-pin connector to emulate the control panel (c.f. ua-cam.com/video/vUH5Tl-q_Xo/v-deo.html):
3. However, at the output of the rectifier (the one at the top of the board) I do measure only approx. 190 V DC, which is far too low in my opinion. At the same time I observe that there is a significant voltage drop at the 33k resistor at the (+) AC input of the rectifier. This is also curious since in my opinion the relay, which is in parallel to the 33k, should close that contact fully during operation.
4. Finally, when I close the relay manually via a wire (bridging the 33k resistor) the board's fuse (including the one in the fuse box of the house @ 16A!) blows.
5. For me it is tough to draw the right conclusions from these observations, but I give it a try:
(A) The low output voltage at the rectifier is OK because the relay is closed only when rotation shall start. So it is OK to manually close the relay to power the rectifier. Thus there is a problem with the large cap (or its parallel companion) with a short at a certain voltage. (B) There is an issue with the rectifier itself (some short inside).
6. Unfortunately option (A) is not even making sense to me, its just rough guessing. In option (B) everything would make a bit more sense but I would be wondering about the fact that the fuse holds in that scenario and that there is such a high voltage drop at the relay.
In general for my understand it would be very helpful to understand (Q1) if I should expect to have a closed relay already after power on and (Q2) the circuitry which switches the relay.
Thanks a lot & BR
Alex'
Hi there I have a trojan treadmill with a DCMD67 board the middle board in your video when I press start on the keyboard it counts down then I hear the relay click in but the motor doesn't turn and the error 1 pops up on the screen
Hi Justin,
Have you tested the motor?
I’m not in CPT unfortunately.
Cheers
Craig
Hi Sir
I have the same problem with my threadmill as Justin above.
I have tested the motor and the sensor and they are working fine. When looking at the board the green diode (FDC+) lights up fine but the yellow diode (written fast/slow on the board) lights up in two series of blips. Do you have any idea what could this indicate?
Thanks for your help.
Arnaud from Mauritius
Hi there,
Have you tested everything in the motor drive circuit? By this I mean the FET, the fly back diode, the FET driver with its associated circuitry?
If the motor is good and it doesn’t turn - then I’m pretty sure it’s the FET.
Cheers
Craig
Sir I have same index incline board once start and suddenly off. What is problem that?. Please respond sir
Hi there,
It is very difficult to tell. What error codes do you get on the master panel? If the motor starts and stops shortly - you have a problem with the speed sensor or the belt alignment. I would start to look at those parts of the circuit.
Cheers
Craig
@@foulkesbrau3085 it's shows e01. It's off within 1-2sec. I replaced Speed sensor.
Well, E01 means the main board is not seeing the sensor. You need to trace the wires. Do you measure the speed sensor where it comes into the main board? Are the wires broken? Measure is the only way.
@@foulkesbrau3085 wires are ok sir
Sir please send me your contact number. I will send a video to help u understand problem
Hi sir , I am facing problem IDCD80N ,ENDEX , DC6 ERROR
Hi,
Have you tried to google the error? When I do, It tells me that you might have a faulty/loose connection between the board under the motor cover and the console.
Cheers
Craig