Electronic Repair

It looks like any old Wurlitzer 200 or 200A electric piano, but it’s actually very rare! It’s a Wurlitzer 200B! What makes it a “B”? Well, it runs on a battery! Two batteries, actually. Wurlitzer made these towards the end of the production line in the late 70s, early 80s, and they are completely bare bones and fully portable using a 240V battery (that looks like a mini cereal box!) and a 9V battery, or AC adaptor. The large battery powered the reed bar, and the low voltage powered the minimal preamp circuitry. There are no speakers and no vibrato. Just a main output, and headphones. The headphone volume is controlled where the Vibrato control usually lives. There is no power light. Out of the 88,000 Wurlitzer 200 series ever made, they only made about 300 of these.

I removed the original circuitry, but kept everything together. I replaced the circuits with a Borish Electronics 200B kit that runs on a 9V battery or AC adaptor, and doesn’t need the hard to find 240V battery. It could be reverted back easily, and I kept all of the original wiring intact. Other than the normal reed bar electronics (high voltage) the original preamp is just a single opamp and a few capacitors and resistors. I kept the original volume controls for main out and headphones to work with the new electronics. The headphone control is where the vibrato control normally lives on a 200 or 200A. For the headphones, I used a headphone amp circuit that runs on the same voltage, but I had to use a 1:1 transformer for its input because it can’t share the same ground as the other electronics.

This piano was purchased new in 1982 for a TV studio in Nashville, TN. It was hardly even used, and was stored most of the time. The 44 year old battery leaked all over causing rust and white powdery oxidation (that battery still measured 2 volts!). The action was about perfect already, and most of the reeds were still in tune. I ended up replacing two reeds, tuned a couple more, and adjusted the strike of two hammers. It definitely has the best action I’ve ever seen on a Wurlitzer!

Curley went over the rusted chrome legs with a disc sander. I washed all the key tops, the shell, removed rust from the metal trim and replaced the pinstripe tape. It cleaned up really nicely!

The new electronics are pretty inductive. I had a hard time minimizing the 60Hz and local NPR station making its way to the audio signal from the air. That involved some capacitors filtering high frequencies, shielded power leads, and then finally turning the inside of the shell into a Faraday cage with grounded foil tape. Finally, everything was quiet, except for the nice sound of the reeds.