drafty

thanks
been in contact with them already. he thinks it is the optical eye..? and can fix it for 99 pounds plus parts (10 pound). i am a bit hesitant because it might not be the problem and than costs will be too high for what the kickr is worth (getting a replacement and just thought i get the old one going and give it to a mate)
thanks again for all your help and feedback you are a wealth of knowledge

unterhausen

He may have meant that the optical sensor smoked the processor. I think that's probably true. The sensor itself usually isn't bad. I expect that the magnet generates a charge that discharges through that circuit.

Since rogers2000 seems to do repair for income, I expect his charges would be about the same.

LouMan69

I was wondering if someone could help me. I have purchased a NRF52832 and a j-link programmer linked in this forum from AliExpress. I have managed to dump the contents from the gem2 module on my kickr successful. However I cannot get j-link to detect my new module. I have tried connecting the programmer directly to the module and also tried using the kickr board to supply power to it but no luck. I have tested all connections and they have no shorts. Is there something I am missing for connecting the unit up?

unterhausen

So you got a module from aliexpress or one of the Gem2 modules?

Just went looking, they moved the store https://npe.fit/collections/oem-solutions

LouMan69

I bought a module from Aliexpress I believe it’s dead so I’ve got another one from Amazon.

JustCope

Hi there. I have a KICKR v3 2017. It only works when I bend the power supply cable up at an acute angle where it enters the KICKR and tape it like that, but would like to get it repaired. I have used the power block and male connector from my wife's KICKR and that makes no difference, so it seems to me that the problem must likely be a loose connection to the circuit board. I have a local electronics guy who will look at it for me, but I just wanted to check whether the only way to access the PCB is by essentially completely disassembling the KICKR, removing the flywheel etc.

Many thanks
Justin

unterhausen

It's unlikely to be the circuit board, it's probably the cable inside the strain relief or at the kickr side external connector.

I was in a state of disbelief that they would make me take the whole thing apart, but it's true; the whole thing has to come apart. The good thing for troubleshooting is that it flashes some leds when it wakes up.

JustCope

Thanks a lot for your reply - I was, however, hoping that you would tell me there is an easier way...

unterhausen

Not that I was going to tell you anything similar, but I just noticed your username

I'm hoping to get a kickr to test repaired boards with, and I was hoping I could open a port in the housing so I wouldn't have to disassemble it for every board I worked on. But I can't see how to get to the sensor, which hard wired on a significant number of kickrs.

unterhausen

thanks for your post. How did you determine it was the sensor, and what part number did you use to replace it?

I think testing the sensor before replacing the microcontroller makes sense, but it seems like the weakest link is the input port

unterhausen

Thank you for your post, that's very helpful. Google does a good job with translation nowadays, your post reads fine.

PDF warning:
https://www.letex.com.tw/page/produc...d.ashx?num=479

So far I didn't find a source for the chip

unterhausen

I would love to know where you sourced the sensor or a suitable substitute. On edit: looks like Mouser lists 3 subs, none of which they stock. the EAITRCA7,IN-P4634ATHIRPT,ITR8307TR8.

I guess I'll look again when I'm feeling better, everyone at our house is sick with RSV right now.

Sambo_Cycles

Hi Rogers2000 are you interested in having a look at my PCB board?
From what I can tell with the mustimeter the U3 is receiving voltage but not sending it out.

unterhausen

digikey has the IN-P4634ATHIRPT in stock
https://www.digikey.com/en/products/...HIRPT/16964339

Info about tvs diodes. Seems like it would be a good idea for wahoo to add them to the sensor board
https://resources.altium.com/p/esd-p...ics-tvs-diodes

unterhausen

Here are my notes about reading and programming the module. Thanks to everyone who posted them
I run the jlink program in windows using the command window. Best to start in a directory where you can store the binaries, because jlink commander doesn't seem to be too path-friendly

Start the program:
c:\Program Files\SEGGER\JLink_V794>jlink

Jlink commander commands to read data:

J-Link>connect

Please specify device / core. <Default>: NRF52832_XXAA

Device>

Please specify target interface:

J) JTAG (Default)

S) SWD

T) cJTAG

TIF>swd

Specify target interface speed [kHz]. <Default>: 4000 kHz note: just hit enter, default is fine

Speed>

Device "NRF52832_XXAA" selected.

Read Firmware:

J-Link>savebin binary_firmware_1.bin 0x0 0x80000

Opening binary file for writing... [binary_firmware_1.bin]

Read UICR (configuration):

J-Link>savebin binary_UICR_1.bin 0x10001000 0x1000

Opening binary file for writing... [binary_UICR_1.bin]
To program:

J-Link>connect

Should see “cortex m4 identified” at the end of a number of lines.

Good practice once connected:

J-Link>erase

Write UICR

J-Link>loadfile binary_UICR_1.bin 0x10001000

Firmware proper:

J-Link>loadfile binary_firmware_1.bin 0x0

Test without cycling power.

J-Link>reset

J-Link>go
Leds should start blinking

unterhausen

Doing some reverse engineering. I'm pretty sure I have the connectors identified correctly. The speed connector appears to be a JST ZH 3 pin. These are widely available online, at pre-wired at Amazon for example. The wire is 120mm long. The power and brake connectors appear to be a JST VH connector. Wire connector is VHR-2N. Digikey has substitutes, doesn’t carry JST brand in stock.

vilaemail

I broke my kickr by plugging in wrong power supply. I've desoldered GEM2 module from PCB and connected the minimum pins (gnd, vcc, swdio and swclk) but it is taking in >1A of current and when connecting JLink it can't download the binary from the MCU. I already have replacement MCU board but don't have what to flash it with.

Can someone send me their kickr firmware binary? @unterhausen maybe? I've tried contacting rogers2000 via email, but with no luck.

Any help is appreciated. Thanks!

dup

Hi @SixOnine, the one I managed to fix with aluminum tape was a 2014 version. Does yours power up and register in the app?

unterhausen

I think SixOnine has the one with a code wheel on the outside, on the main flywheel that holds the cassette. I suppose it's possible theirs just needs to be cleaned, that was an issue for a while.

The newer trainers still have a black and white code wheel, but it's inside the mag flywheel (for lack of a better term). That seems to be a big issue with the newer ones, I'll post a picture of the code wheel from one later. It almost looks like it has been in a microwave. I assume that's from static discharge. I almost wonder if the code wheel reaches a point where the black and white parts look the same to the sensor. When they announced a fix for this problem in 2018, they said the earliest ones had a static discharge problem, but it seems a lot less likely to be an issue with that external code wheel. I have seen a couple of reports of kickrs with intermittent power readings. I am wondering if that's because the connector to the sensor gets flakey.

Travis F

Hello all,

I just registered to give a BIG thanks to everyone sharing their knowledge in this post. My 2018 Kickr stopped transmitting speed, cadence, and power data around the middle of January. After much research I landed on this thread. After reaching out to Wahoo and getting no real help other than an offer for a 20% discount on a new unit, I decided to purchase some parts and try to repair myself. I sourced the IR sensor from Digi-key and sourced the GEM2 module from North Pole Engineering (thankful they sell these to non-OEMs).

I successfully replaced the IR sensor, extracted the firmware from the GEM2 module, replaced the GEM2 module and loaded the firmware to the new module. I don't think this would have been possible without the knowledge sharing in this thread.

I am not certain what caused the failure but when I replaced the IR sensor I found a lot of tiny metal shaving all over the three wire contacts on the board. Further investigation lead me to find that a new cassette I had installed had a bit of wobble to it due to not seating completely. I believe that the misaligned cassette and a new chain meshing created these small metal shavings. I am assuming that the magnets drew the metal in and when de-energized drop these shavings on the IR board.

Thanks again ALL!
Travis

maksim1987

Friends, hello! I bought a new Gem2 chip, but I can’t get the firmware from the old chip because it’s short-circuited and it’s generally impossible to get information. Can you download the firmware for GEM-2? I was refused official support.

unterhausen

I hope someday to figure out how to reverse engineer the serial number in the firmware, but until that day I'm somewhat reluctant to share firmware.

I think I linked the people that repair boards somewhere in this thread, they have said they have firmware.

sampech97

Hey I stumbled upon this thread and had a question... I recently bought a used kickr core that wasn't showing power, speed, cadence in the app except when jumping the connection at the IR sensor. The voltage going into the sensor is 3.3V but only 0.63 is going out and leading to the GEM2 module. My question was whether or not you think only the sensor need replacing or whether the GEM2 chip also needs to be replaced? The Kickr did update to the newest firmware successfully but when I contacted Wahoo they said it was a hardware issue and since it's out of warranty they won't replace it.

unterhausen

That doesn't sound right, and the sensor costs $1 and is relatively easy to replace.

cudasbroknkickr

Hey rogers i'd like to see if I can get my buddies kickr repaired also. Would that be possible? Thanks