kevin999

I have a Wahoo Kickr with a damaged circuit board. Only one part is damaged and I could replace it if I knew the part number, but the markings on the part (that tell you the part number) were also damaged. If I had a hi-res picture of the circuit board from a working unit, I could recover the part number, buy it and repair the circuit board. Of course, I realize one would have to disassemble their unit sufficiently to access the circuit board to take a picture. But it is just a few fasteners that use standard hand tools. The picture would need to be clear enough to read all of the markings on the specific part. The part in question is marked Q1 in white text on the circuit board. Any help is much appreciated. Thank you.

steelbikeguy

if you have a picture, maybe you could PM it to me and I could post it? I'm kinda curious myself.

In general, though, parts are so small that there is very little marking on them. Generally, there are 3 characters on SOT-23 components that are typical of transistors. Here's a shot of the circuit board from a B&M Eyc light....




Steve in Peoria

kevin999

Hi Steve,

Apparently I can't do PMs yet until I get more posts. Thanks for your effort. My circuit board is different than the one you shared. Once my account gets to 10 posts (allowing me to post pictures and PM folks), I will update this thread so you can see what I am talking about.

Kevin

unterhausen

if the picture is online (flickr, etc) leave a visitor message on my profile with the link and I'll post it

steelbikeguy

maybe a link to the photo? (I'm not familiar with what is allowed for new members....)
Or just keep chatting until you get to 10 messages... So how's the weather?
or discuss how you have decided that a transistor is bad?

Steve in Peoria

unterhausen

if he has a link and saw my post, we will get the picture posted for him.

kevin999

I can't even post a URL until I have more posts.

kevin999

So I am trying to get more posts.

kevin999

The weather in northern california was been super wet and rainy. Now, after the clock-change, our local race ride starting up again.

kevin999

But the WAZE apps are re-routing freeway traffic onto our country roads. So we have to change our route.

kevin999

To add a bit more information, the trainer is the normal KICKR model from 2016.

steelbikeguy

isn't "wet" somewhat normal for northern California? I've only been in the area once, though, and that was in the summer. Very nice!

Steve in Peoria
(not a very wet winter/spring so far, which is fine with me)

steelbikeguy

A couple of decades ago, I lived in the St. Louis area. Traffic was mostly on the interstates, and could be fairly miserable if you were going in the wrong direction at the wrong time of day.
I was down there recently and went for a ride on my old favorite roads in the afternoon... and it was a mess! Traffic had migrated onto these formerly pleasant roads and turned them into slow moving parking lots. Another reason that I'm glad that I left there. (but there is still some fine bike riding in the outer St. Louis areas, especially out west)

Steve in Peoria
(very much enjoying riding in the low traffic in Peoria as well as the vast expanses of rural areas surrounding it)

kevin999

Okay, back at it. I could only make 5 posts in 24 hours.

Yeah, "wet" is supposed to be the norm in Northern California this time of year. But it increasingly seems like there is no norm any more. 5 out of the last 6 years have been drought years, but then this February was one of the wettest Februaries on record.

kevin999

Sorry to hear that the traffic apps have messed up the nice quite roads in other places. It really is disappointing.

kevin999

Last post of my probation.

kevin999

Okay, at long last. Here is the picture of the circuit board. The part in question is bottom middle, labelled Q1, with the red box drawn around it.

unterhausen

I probably have the same trainer, can you take a picture of what I have to take off? Looks like that might be part of the braking circuit, which suggests a power transistor

steelbikeguy

well, I can see why you thought Q1 might be bad!
what the heck happened to it, though? There's no sign of overheating, which is usually why chunks of the package get blown off.

Based on what I can see of the circuit board traces, my first thought was that Q1 was used to prevent reverse application of power from the connector on the right. However, the source and drain should be connected opposite of what they are, so that idea is out.

The next (last?) idea is that it might be a N channel mosfet (or npn transistor) switching a high side load. I think the diode, D1, is meant to be a freewheeling diode to handle inductive kickback. That load would be whatever hooks up to the two-pin connector on the left......



so what connects to that??
Whatever it is, that should be the only part that isn't working.

and just out of curiosity.... what does this gadget do? There's almost nothing on it other than the bluetooth radio mondule.
edit: the internet tells me that this is for an indoor trainer, so I'm guessing that the "brake" is somehow controlling an eddy current brake that acts as the drag for the trainer. It's probably an inductive load, and probably pwm'ed, so the flyback (or freewheeling) diode is important. It might be important for the mosfet to have a low Rds to avoid overheating, in the event that it is carrying much current.

anyway... my guess is that this is a N channel mosfet from On Semi (formerly part of Motorola). The code on the package is mostly just telling when and where it was made. The actual device info is probably on the part of the package that's missing.
Here's a datasheet for a somewhat similar mosfet from On Semi..
https://www.onsemi.com/pub/Collateral/NTD3055-150-D.PDF
The package is a D-PAK, and any logic level N channel mosfet is probably okay.

Anyway.. that's my guess. Looking forward to finding out what I overlooked.

Steve in Peoria

patmcb12

Hi Kevin. What made you think that you were having a circuit board problem?
I recently bought a very lightly used 2018 Kickr. Brought it home and plugged it in and accidentally plugged in my old trainer’s plug into it. It produced the tiniest spark. I then plugged in the chord that came with it and it won’t turn on at all. Could this have caused it? The people I bought it from swore there was nothing wrong with it but said they would refund me the money if I couldn’t figure it out. Did some searching but couldn’t find people with the same problem.

thanks
Patrick

gsa103

Look at the voltages on the power supply. If the old trainer had a 24V power supply and the Kickr uses 12V that could definitely fry the circuit board.

unterhausen

He didn't even answer after I offered to take my trainer apart to find out what that part is, so I doubt he will come back and answer any more questions.

mjb1970a

Good evening.

mjb1970a

I’m searching for advice on a 2019 kickr core and realise that if i want to ask and questions I’ll need to make a few posts first.

mjb1970a

my question will be about fixing the PCB fault But also about how to open the kickr up. I’ve got some of the casing off but I can’t work out how to get into the PCB. Any tips appreciated