# Converting a dead smart trainer into a dumb trainer?

Have I understand correctly that you are trying to convert dead Wahoo Core to usable dumb trainer?

I would suggest to try using electromagnets before modifying unit for permanent magnets.

If trainer is Core, power supply for working core is 12V 5A PSU which delivers 60W of power and that is enough to make full resistance for that unit. Max power for Core is specified 1800W (not indicated what speed, sadly).
This following calculation is quick assumption that all PSU power capability is needed for full load. So if the target is to archive resistance for 700W load, then supplying electromagnets power of 700/1800*60W = 23,3W would send one to ball bark.
To get ca 23W power to electromagnets one needs to supply 7.5V with 3A rating.
Measuring resistance of electromagnet coils would help to focus calculation. Off cause there is option to start with lower voltage feed, like 5V / 2A which could provide 300W load.

Math aside, do you know how and were he would actually connect this PS to the trainer? Presumably you are talking about bypassing the PCB and going directly to the EM’s in one way or another?

Yes, bypass PCB and feed power to EM’s directly, there one connector with two wires feeding EM’s. Polarity don’t matter on this case.

FCC reports internal pictures can be found here: https://fccid.io/PADWF123/Internal-Photos/Internal-EUT-Photo-3850566

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If I was to bypass the board and use the electromagnet, I would want a remote control dial to adjust the resistance.

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There is plenty of DC-DC converters on Aliexpress under \$1, which could do the job. Like this:[https://ae01.alicdn.com/kf/HTB1bi6pUQvoK1RjSZFNq6AxMVXa5.jpg]

But before ordering one it would smart to verify what is actually needed / feasible. I would start by supplying 5V to EM’s and by riding verify load level achieved .

I’m not an electrical engineer. I can barely crimp connectors and solder. Explain like I am five.

To begin with, Is you trainer Wahoo Core?

Do internals look same as in FCC report pictures as on link I posted earlier?

Yes. Probably?

I mean I need to know exactly what components I would need to be able to adjust the output from minimal levels (resistance floor) to maximal resistance (1800 w).

If your original power supply is OK then all you need is adjustable DC-DC converter to replace your current PCB. But if you aim to full 1800W maximal resistance, there is danger of overheating EM’s.

If I were you I would just bypass PCB by connecting together wires from psu connector to EM connector and leave backdoor open to restore unit back to smart trainer. Just in case if suitable PCB-repairer/new PCB could be found.
Then I would use some PSU (or original PSU) and connect DC-DC conv between PSU and Trainer power supply connector.
Externally connections:
Mains power → PSU → DC-DC conv → Trainer power input.
Internally connections:
PCB power input connector → Bypass wires → PCB coil connector → EM’s.

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…is there some reason I can’t just hook the electromagnet straight to a light bulb or something?
I mean, a brake is basically a motor, is basically a generator… Hehe.

It is not a generator, it is eddy current brake.

Ineos (apparently) somehow used Kickrs to power Christmas lights in a video several years ago.

Bike racing team with skillful mechanics, there should be no problem to change flywheel with permanent magnets equipped one. At least to level for powering decorative fun lights.