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Treadmill display controller repair help

dafa_123

Nov 14, 2021
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Hello, I was given a non working NordicTrack 1750 treadmill with a non working console. I took it apart and from what I can see, there is a problem with the display portion of the console. I can read 12v on the console and getting to the display board, but I have no life from the display. Nothing comes on. I took the display board apart and started testing the tiny components and I would like some advice.

The board I am working on is identify as 8591C V2.0. I think that I found a defective diode, but since I am not an expert and only have a basic understanding of how component work, I was hoping to get some advice since I was unable to find any diagram for the board.

When I put my meter on diode mode and poke at D4, I get 1.762 one way and 0.151 the other way. From my basic understanding of a diode, I should only get a reading from one way.

Any help will be welcomed.

Thank you.
 

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Harald Kapp

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Nov 17, 2011
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Without very special equipment you can't reliably test components within the circuit. Other components will influence your readings. To test the diode you'd have to remove it from the PCB (note the orientation!) and put it back after testing (assuming it is o.k., otherwise you'd have to find a replacement).
While not impossible it is not very likely a single diode fails here.
Check the supply voltages on the pcb. The chips are not operated from the 12 V going into the board. There will be voltage regulators (presumably next to the 12 V input to the pcb) that create 5 V, 3.3 V or other lower voltages for the rest of the pcb. Check these voltages first.
 

dafa_123

Nov 14, 2021
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Ok. I have 2 components that look like voltage regulators near the 12V input. I am pretty sure that U29 is a voltage regulator, but I am not sure about U10 since I can't seem to find any datasheet for either of them.

Thank you.
 

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73's de Edd

Aug 21, 2015
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Sir dafa . . . . . . . .

I am working with your VERY first info NOW, but I see that you added in ONE good pic . . .the first one . . . about the 12 V presence, lets go with expecting that voltage level, as supply voltage over in your " RED ARROW " area.
So I now continue on, with your first post.

Well the NordicTrack 1750 units book tells me that the display is using a 10 in tablet for its display . . . . but not what connections are needed from that display to the rest of the unit. Possibly just that USB connector ? and are you using the proper port ? OTG ?
S o o o o o o o in just going with your board corner that you were initially showing us, let me just initially work with that.
You have concentrated on the top left corner of that board and that seems to be dedicated to creating two + and - polarities of power supplies at a current capability of ~ 300 ma if so needed. You will be finding out those voltage values when you test . . .IF they are there..

Now, with your initial fixation on that specific diode, and its junction voltage reading . . . . . reveals :
I get 1.762V one way and 0.151V the other way.
One might expect a lowest 0.500 V through 0.700 V highest reading on common silicon diodes being used in that application.
BUT, your 0.151 reading, falls right in line with a Schottky family diode, and your 1.762V reading is PROBABLY fully attributable to circuitry that is also shunting across that diode.
To be sure, one needs to lift one leg / terminal completely out of circuit to test that way.
BUT since that is a surface mount, it would require a heating of both tabs and getting the solder molten . . .and THEN the grip in the center with a pair of tweezers to enact an ~ 45-90 degree twist on the body to break the adhesive under the diode to the PCB loose . . . then you are broken Free . . . . FREE AT LAST !
BUT . . . BUT . . . . BUT ! . . . . I would not ask you to do that , for your then finding out my 99 86 / 100 ths % suspicion of that unit being absolutely and totally O.K. ( Remember those 0.151 magical numbers ? )

Instead, lets consult the application note / schematic that TI provided for their little gem of a dual voltage converter.

INFORMATION CENTRAL . . .is now . . . PRESENTING to you . . . . . .Ta Da . . . . .

upload_2021-11-15_10-36-56.png














Study this schematic and initially note input power comes in to top left corners V1 GREEN A position and then routes to Q1 power switching FET and to pin 5 or 6 Green B of Tipsy 65130 Eye See. This feeds an internal FET for your negative supply portion.
Also note the power branch thru pi filter of C2 - R7 - C3 and on to pin 4 Green C of the IC.

VOLTAGE CONVERSION . . . . . OPERATIONAL RUNDOWN . . . .

Using the PINK markup of the Positive supply, and we will assume that +12 that you have already found on the board will be coming in to GREEN A and then to S of Q1 and wanting to pass thru to D . . . . but no can do until gate activation.
But, a stream of pulses are coming to that gate from pin 7 BSW.
Specifically at 1,250,000 pulses per second . . . . .on upwardly to 1,500,000 PPS, in accordance to PS operating conditions.
You might say we have ourselves a pulse train there, with no WAITING at the station, but you may have one HARD time picking out YOUR train.
( PLUS . . . . Man that's being one HELL of a LOT of pulse " trains " per second ! )
HEY ! lets keep going on with this train analogy.
As for the POWER supplied by these trains, relate that to the number of box cars pulled with their "energy", a train might have as many as its 87 boxcar pulling limit or as short as 12 cars. ( 87% pulse width or 12% pulse width. )
So we now have the individual pulses coming in to the Q1 gate and it has its gate turned on for the required duration of that pulse ( a train and its box cars)
That Q1 conduction is letting the REAL energy coming in from that 12V supply, be fed into the L1 inductor which starts building up a magnetic field proportionally to the incoming pulses width (duration). At the instant that the pulse ends Q1 stops power flow due to no gate drive.
BUT that strong magnetic field having been created within the L1 inductor, then collapses, and the falling magnetic field creates a strong back EMF, ringing waveform as can be seen illustrated in the RED asterisk inset. D1 diode then captures that energy to pass on down to C4 storage cap / filter down near the GREEN G at the right top end of the schema.
As C4 it is building up its stored voltage, a simultaneous sampling it taking place at GREEN E , where R1 / R2 voltage dividers center junction send out a voltage to GREEN K at FBN.
FBN then sends any required correction to the oscillator and Schmitt trigger portions of the pulse generator, that feed into BSW gate drive to alter either / and / or its frequency or pulse width.
( Slow down the number of trains and /or their numbers of box cars. )

Same procedure down at the BLUE portion of the schematic for the negative supply, excluding the "Q1" equivalent, which is being
internal of the IC. Its corrective voltage sampling is from GREEN J and feeds down to the R4-R3 voltage divider junction which feeds to GREEN K , so that it can make corrections to its FET driver.

YOUR TASK AT HAND NOW . . . . .

You now just need to find 4 test points, and as close as those IC terminals are . . . .even with needle probes, and YES I do use soldered on needles for a set of my probes.
Best you have a DEAD non powered board and use the supplemental IC basing I added at the bottom with its dimple in the chip corner pin 1 marker, and count around.
Pin 2 or 3 will give you ground, and an ohmming around the board should find another connector with somewhat GREATER SURFACE area to place your - meter probe on.
Pin 5-6 , the same way, in finding that SAME connection but on larger real estate.
Pin 23 will give you this units + power out or any of the also connected terminals of C4's equivalent on this board or preferably D1 equivalency.
Pin 15 will give the negative supply from the unit.
I would mark and identify those alternate test points on the board with a mini Sharpie.
Then its power up and put meter ground to your preferred ground alternate and then probe power in to see if this is using +12 v input . . . and then . . .and then . . . and then . . . do we have the supply's + and - outputs ?

OBSERVATIONS . . . .

Looking around and about your very first photo.
We have your red arrow and the nearby L13 and another L17, items, I perceive both as strip line thru ferrite bead RF / EMI chokes.
That is then leaving the bulky round L18 as being our L1 equivalent ringing choke for the + supply.
Just below it is a "U37" which I really think is being a power FET, with enough support circuitry inside, as to deem its IC classification . . .U identifier . . .vice Q for a transistor.
Top and left of L18 is D14 which, by its proximity, I would deem as being that inductors associated diode . . .your D4 is being TOO far away, as per defying good design practice .

Find your IC pin 1 dimple and it points down to L16, as I suspicion to be our other ringing inductor for the negative supply.
D9, just above it, seems to relate as its associated diode.
I am wanting to think that the CA 35, just below L13 is being a monolithic high density X7R ceramic capacitor for that C4 equivalency main storage cap for the + supply.
If you find those + and - voltages being present, then check both sides of YOUR RED D4, just to see if it might be associated with the 12 VDC supply that you are finding present.

I now stop . . . . to let you update me.
EatingPopcorn.jpg


Here's your U10 . . . . . Da Da sheet

https://www.digikey.com/htmldatasheets/production/1785837/0/0/1/nb634-datasheet.html

What supply voltage is being found at its pin 1 ?





73's de Edd . . . . .

Now I may not be as funny or athletic or good looking or smart or talented or experienced or rich or wise or . . . . . . . . ??? . . . . . drat, I forgot where I was going with this.


.
 
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dafa_123

Nov 14, 2021
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Thank you for the reply. I have ordered some tools to help me work on such tiny components. I should get them this week. I will keep this thread up to date on my results once I get the tools.
:)
 

dafa_123

Nov 14, 2021
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Ok, so I got myself a microscope, needle point probes and a bench PSU and did some test today. I took a bunch of reading on most of the components while connected to ground. U10 seems to be working normally. I think the the CPU and other component using 3.3v. or less are not beeing powered. I am trying to figure out how I could test if the CPU is getting powersince I could not find the datasheet and all the pads are under the CPU?

I tried to find the datasheets for the components, but there are many that I cannot find. From what I understand, the Max8698 is the one that should be provinding 3.3v to the CPU and other components that need 3.3v. Since all the pads are under the IC just like the CPU, I am not sure how to proceed to test it.

Any advice would be welcome. I have attached a bunch of pictures with the mesurement that I took. All points with no mesurement show no voltage when the negative probe is connected to ground.
 

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dafa_123

Nov 14, 2021
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I am really starting to suspect that the Max8698 is either defective or not working properly. From what I can understand from this circuit board, the Max8698 provides power to the CPU, memory and other non 5v components. I made some measurements and I get 0v from all of the LDOs except for LDO1 which provide 3v by default. I see IN1, IN3, IN4, IN5 and IN6 are all at ±5v. From what I undestand from the datasheet, the LDOs should be giving me some voltage and not just 0v. Could this be my issue?
 

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dafa_123

Nov 14, 2021
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Replaced the PMIC and I have the same issue. Must be something else.
 

ssinfod

Dec 22, 2021
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Dec 22, 2021
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I'm also in the same situation... I own a NordicTrack Threadmill C1600 PRO and the touchscreen is black (no backlight) after power on.
In my case, it seems the problem was caused by a software update. Indeed, I did an update and everything was fine until I did a power cycle with the power switch.

I have the same PCB board (8591C V2.0 / 2013.07.29)

I called Icon / iFit / Nordic Track and they told me that the console is no longer available for purchase.
Also, my threadmill is no more under warranty. However, they sent me a micro SD card but it did not work. (Screen stays black)

I'm considering to plug an Arduino or a Raspberry Pi to the 10 ribbon cable.
Otherwise I'm considering to buy an generic console/controller (ex: https://www.aliexpress.com/item/1005001523947945.html)

I find it disturbing that the console does not work for more than 5 years.
 

dafa_123

Nov 14, 2021
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If only the display is dead, I think that I have found the one they used. It appears to be a Logic Technologies LT161010-2NH. https://www.mouser.com/datasheet/2/...apacitive-touch-display-800x480-v-1770786.pdf. My problem is that I have no power coming out of the PMIC except for LDO1. I replaced the PMIC but I have the same issue. Either the screen must be working in order for the PMIC to provide power to the other components or some other component as failed and is necessary to activate the PMIC. I am not knowledgeable enough with how a PMIC works to be sure.
 
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dafa_123

Nov 14, 2021
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Turns out the PMIC is working but the LCD looks dead. The LCD model on my treadmill is AT070TN92 V.X. I will order one from Ebay and see if it fixes the issue.
 

ssinfod

Dec 22, 2021
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Dec 22, 2021
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Hello dafa_123,

Here are more information about my display controller (console).

On the back, it says:
ICON Part No.: 349765
POWER SOURCE: DC 12V 2A
POWER CONSUMPTION: 24W
MODEL NO.: 349765
FCC ID: OMC339918

Regarding the LCD, I see the following number on the metal casing at the back of the LCD:
INN070DP26V1 ZM70129A 140929 ROHS
MF-ZC70062NN-03F

I will also try to do some power verification on the PCB.
I will keep you posted.
 

sreelectronic

Mar 8, 2023
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Mar 8, 2023
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I have the same issue with Nordictrack t series with no display but 12v is in the back of the lcd, I found a mosfet in the lower controller called JCT425i that is failed but I couldn't find any replacement, I'm not sure if the problem related to that part or it's related to lcd controller, this controller also has reset key socket that I'm not sure needs to be connect or not for turning on the lcd, anyhow I don't know where should I start troubleshooting, thanks for anyone could help me to identify the issue. Thanks
 

zman

Jun 5, 2023
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Hello dafa_123,

Did you ever resolve the controller board problem? I have the same model control board that you mentioned and mine quit functioning also. It seems the MAX8698 is only supplying power on LDO1 just as you confirmed. I have the datasheet and it shows there is a power enable pin and a power on pin, both inputs to the IC. One or both pins may need to be activated in order for the other power supplies to output. However I don't know what normally drives those inputs. There could be some external signals required.
 

dafa_123

Nov 14, 2021
9
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Nov 14, 2021
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Hello dafa_123,

Did you ever resolve the controller board problem? I have the same model control board that you mentioned and mine quit functioning also. It seems the MAX8698 is only supplying power on LDO1 just as you confirmed. I have the datasheet and it shows there is a power enable pin and a power on pin, both inputs to the IC. One or both pins may need to be activated in order for the other power supplies to output. However I don't know what normally drives those inputs. There could be some external signals required.
Unfortunately no. I replaced the treadmill with a cheaper model with less electronics. I did not find anyway to replace only the board. I would have needed to buy a complete console which was more that the price of a used treadmill.
 
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