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Anthony F.
Anthony F., Engineer
Category: Electronic Musical Instruments
Satisfied Customers: 9830
Experience:  Amplifier and keyboard repair.
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Hi there! My B3 tone generator spools up when I engage the

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Hi there! My B3 tone generator spools up when I engage the start switch but will not maintain RPM when the run switch is engaged. Additionally, I do not get any response what so ever from the motors in the Leslie, and I am not getting any warm and glowing tubes on the AO-28 or the Leslie amp. The run lamp does not illuminate either. What do ya suppose is wrong?

Sounds like you have an open fuse or an open primary winding in the powerr trasformer
replace with the same fuse not bigger
if it blows again you have an issue with your final tubes
replace them

if you have a spare replace it but only after you look for an open fuse

it could also be an open filamnet in a tube as they are wired in series and if one opens the others may not light

 

Customer: replied 3 years ago.
Thank you sir. I have the schematic for the AO-28 in front of me. I don't see a fuse anywhere. Can you pull your schematic out and tell me which component is the fuse? Am I missing something? On visual inspection, there is no "user replaceable" fuse visible anywhere on the AO-28 that I can see. If a fuse exists, i guess it's internal.... meaning that I must desolder and replace it.
look in the power supply to the organ
the power comes from the B3 power supply
Do you have a meter?
T7 Transformer is the power supply
make sure the ORGAN is feeding te transformer primary with power
then we can check for secondary volatges including filament
the problem may be further back in the organ
Customer: replied 3 years ago.
Yes, I have a meter. But the synchronous run motor is "before" T7. The way I read the schematic, the synchronous motor should run even if the entire AO-28 was absent. I have no power downstream of the run switch. Seems to me that the run switch has failed. Agree?
the motor is bad or the whole unit would be dead
if the switch failed
no downstream power to anything except the starting motor?
unless thats what you got?
Customer: replied 3 years ago.
Yes, correct. Everything is dead after the start motor. Nothing at all happens when the run switch is engaged.
sounds like the switch is the issue then
but you can test it
you have a meter and the schematic
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