

Master degree in EE here. It will almost certainly be fine to swap those batteries like that, I would be more cautious if it was some cheap Temu device but for a vintage Yamaha you’ll be fine.
One thing I will caution you about though, the synth almost certainly lacks under-voltage protection and could drain your 18650s below their minimum voltage. Make sure your cells have built-in protection or add some of your own.














Androcur is expensive but extremely effective. The general advice is you only need to take a quarter of a standard 50mg tablet per day instead of a whole tablet, but I found that once my T levels were suppressed, I could maintain an undetectable T level with only 12.5mg of Androcur per week. The 1mg of cypro in Climen might be enough for you to maintain low T levels, you’d just need to try and find out, but I would highly recommend taking Androcur for at least the first 3-6 months since that’s when most breast growth occurs and so has the highest chance to be impeded by high T levels.