this is a know issue of MiniBrute. When the Mod wheel controls the LFO amount, and is set to 0, moving the LFO Pitch amount will detune the machine. It could be indeed up to almost 1/2 semiton in the worst case. Every machine should have this behavior, but more or less noticeable.
When the Modwheel is used on the LFO, the LFO goes through a simple VCA that does have a DC output offset, even if the amount is 0.
Unfortunately, this offset is different on each machine. This is why their is a trimmer on the PCB that is supposed to reduce this problem.
But it turns out that the offset changes with temperature. So the trimmer has been set so that, at a classic 20°C to 25°C room temperature, after a 30 minutes warm-up, the de-pitch due to LFO amount should become smaller. At startup the detune should be worst than after a long enough warm up.
Can you please tell me what is the observed detune after a minimum 30 minutes warmup?
Mod wheel set to LFO, mod wheel position 0, measure pitch with LFO Pitch amount at center position, then measure pitch again with LFO Pitch amount set to max.
Let me know