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Discussion Starter #1
I have an old Yamaha Electone organ that I performed some surgery on to extract and build a midi foot pedal (it's great!).
But I noticed there's a nice little 40W speaker as well as presumably an amplifier in there somewhere that was previous used as the organ speaker as well as some nice vintage tweed. I was hoping I could extract those pieces into a new homemade cabinet and end up with a nice little portable keyboard amplifier, but am not sure where to start.

I've done quite a bit of googling, but haven't been able to track down anyone who has done something similar. Does anyone have any recommendations? If extracting the amplifier is too hard, i could also drop in a new one, but thought it would be great to re-use the original amplifier + speaker. Thanks!
 

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Got any pictures?

Shits not hard to do if you know how to do it but it can be difficult if you don't have any electronics skills. You have to track down where the audio signals go into the power section which should hopefully make themselves obvious by larger semiconductor chips on heat sinks. If it has many legged chips on a heat sink, you can look at the datasheet and find the input there. If the electronics designer helped you any, there may be text on the circuit board pointing this out. If you can find it, a buffered booster pedal can help interface the guitar to the amplifier.
 

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Discussion Starter #3
I’ve finally been able to get back to this project. Going to do a little searching to see if I can track down some circuit diagrams for this thing online. Attached is a shot of the segment of the board that I believe to be responsible for power disitribution and I assume also the amplifier?

273F16F3-49BD-48CD-97D0-B5063C8FAED2.jpeg

2AB0D2F1-C27B-43E2-A93D-D39CCA68B6BF.jpeg


Failing that, are there any recommended third party parts/amplifiers components I could use to just drive the speaker and solder on some time and volume pots? The end-goal is a simple piano amplifier.
 

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The board with the two power transitors bolted to a heatsink, and the two trimmers is clearly the power amplified, although if you could build a MIDI unit I assume you probably knew that already.

Would there happen to be a top octave divider chip in there by any chance?
 

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Do you know which Electone model it came out of?
I’m not exactly sure but looking at photos online it looked pretty similar to the B2-R sometime in the 70s I believe. Everything hand soldered and tiny string ties bundles of wire - almost no traces on this thing at all.
 

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Thanks. I might go this route instead. Can’t remember if the speakers or the amplifier should be bigger wattage, I think the speakers have to be less than the amplifier, correct?
Speakers should be bigger so they can handle the total power output.

If the speaker was less wattage, it would travel to far, possible ruining the spider and jumping out of the magnet if to great. The voice coil itself may get to hot and break or short as well.
 
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