A new power supply for a Yamaha DX21

Look at this horrible “repair” job someone did to the power supply of this Yamaha DX21 (which broke again of course)

The main electrolytic capacitor has been replaced with just some other one, definitely not a low-ESR type, connected with quite long and thin leads and then glued into place somewhere in the case. The switching transistor is glued into place too and the traces leading to it are almost, but just not quite broken.Yamaha DX21 (3)

An additional power LED had been added, but instead of connecting it to the 5V rail, it is connected directly to 230V via an capacitive “led power supply”.

Yamaha DX21 (2)

Last but not least there is some strange sticky stuff all over the place, might be electrolyte from the capacitor, or some kind of glue that was used for something. It is hard to tell, it is an awful mess in there. Yamaha DX21 (1)

In cases like this instead of trying to fix the existing power supply it is better and cheaper to replace it with a new one.

Yamaha DX21 (4)



Sequential Tom power supply

This Sequential Tom needed a new power supply. It states to need 15V AC, but after a little bit of reverse engineering it turned out to actually need 2×7.5V AC. It is quite unlikely to find a wall adapter with 2×7.5V AC, so I had to build an own power supply. It is just a (fused) transformer in a case, and a plug attached to a cable that fits into the back of the Tom. Done 🙂

sequential tom (2)