Voltage conversion of Accuphase E-650

@leecc73

I think the fuse is non reset-able and able to withstand till 300v. here the model i find

Littelfuse 36911000000 369 T1A 300V Fuse micro fuse Time-Lag Radial Lead Square Fuse.

Thanks for the info, in that case, the fuse will blow if exceed its power rating. However, IMO, 1A fuse is too high and unable to protect this transformer.

The funny part is i was not able to measure any resistance after the fuse, meaning the 2 legs of the transformer, i suppose it have few milli ohms.

That’s weird! unless the primary winding is shorted (due to over voltage?), it should has more than 10 of ohms resistance for such a small transformer. I got reading of 24ohms on primary winding of a 24VA transformer and 36ohms on a 12VA transformer. You should measure it with the blue and brown cable disconnected to get accurate reading.

The Transformer is tiny 2VA, such of high resistance.

The brown and blue line is from same source, meaning hot wire.

Hello, I would like to request advice regarding changing the voltage of Accuphase A75 from its Japanese 100V model to 230V. While I have experience with voltage conversions, this is my first time working on an A75 model, so your assistance is greatly appreciated.

The basic modification plan involves rewiring the main transformer wires in parallel, replacing the fuse with an 8A slow-blow fuse, and changing the relay jumpers from J1 and J3 to J2. I intend to include circuit photos for reference. I have already measured the resistance allocation of the main transformer wires using an LCR meter.

https://drive.google.com/drive/folders/1jEZNpgb04ZSw6yBU3Tum0yNrq4RdXZ6P?usp=sharing

1. Orange - 120V Red - 100V Grey - 0V

2. Yellow - 120V Brown - 100V White - 0V

To achieve 230V, I believe I need to connect Orange to Grey and Yellow together in parallel, leaving White as it is. If you have any advice or suggestions, please share them. Thank you!!

@imhififan 

Just confirming that for the E-470, switching the voltage from 100V to 120V requires only moving the connectors from K3 to K5 and K4 to K6, with no change to the jumpers J1 and J3.

https://ibb.co/4fT3dys

https://ibb.co/WWfHVj6

@dbxdx5 

Yes, switch the voltage from 100V to 120V, leave jumpers J1 and J3 unchanged.

Thanks for confirming. Do you tweak the bias after doing a voltage conversion?

@dbxdx5 

While it is not necessary to bias the power amplifier after voltage conversion, I thought it would be a good idea to record the rail and bias voltages before conversion for future reference.