Hi there,
there has already been a discussion on that, but with not satisfying result.

Does anyone know for sure the differences between Tonka and Galaxy PCBs (on 7200.10 drives in my case)?
I have a drop dead Tonka in the workshop (no terminal output, yet the crucial voltages for the controller are ok) with a rather hot but not burned Smooth chip. Needless to say that it does not spin, but fortunately there are no fatal voltages on the preamp pins.
If anyone has tried it: would it be enough to swap the Flash ROM from the Tonka to the Galaxy board, or does the MCU also contain adaptive data/firmware? Its a 100404226 in case of the Galaxies.

Here's the answer: it does not work. With the Flash ROM transferred it still identifies itself as Galaxy and the complains about a wrong YUMA chip.
I've found that the core voltage to the MCU ist actually missing, where a working HDD shows 1.3volts, the Tonka drive has 0.00. I've traced the circuit back to a pin of the Smooth chip which should drive this Vcore stepdown, but it doesn't. So I'm now preheating the rework station and swap the smooth.