Hi
The attached is a power supply schematic of a Pioneer A-656 amp.
I am wiring it up for 240 volt operation.
Using pins 2 & 5 as the primary connections.
In the schematic it shows pin 4 , connected direct to neutral , with what appears to be a fuse ?
I have not seen this symbol before.
Any thoughts.
Thanks for listening.

View attachment 238193

 

My guess would be a transformer fusible link or thermal overload symbol meaning it should always be in the power circuit. I would suspect a move of the wire from 3 to 5 while leaving the other wire at 4 would be the proper way to go. Lots of Japanese equipment had tap provisions for 200VAC 50/60Hz operation on the power transformer that might not be on the English versions of the drawings.

 

Agree, thermal cutout. You can bypass it by connecting to pin 2. NOTE: This Is Dangerous.

ak

 

Typical voltage operation switching circuit.


The transformer protection stays in the circuit with other taps are switched.

 

Hi
The attached is a power supply schematic of a Pioneer A-656 amp.
I am wiring it up for 240 volt operation.
Using pins 2 & 5 as the primary connections.
In the schematic it shows pin 4 , connected direct to neutral , with what appears to be a fuse ?
I have not seen this symbol before.
Any thoughts.
Thanks for listening.

View attachment 238193
[/QUOT

My guess would be a transformer fusible link or thermal overload symbol meaning it should always be in the power circuit. I would suspect a move of the wire from 3 to 5 while leaving the other wire at 4 would be the proper way to go. Lots of Japanese equipment had tap provisions for 200VAC 50/60Hz operation on the power transformer that might not be on the English versions of the drawings.

View attachment 238194

Thanks for your reply , could not find that symbol (fuse in circle) , but make sense now.
As you say , i should connect neutral to pin 4 and active to pin 5.
Best regards.

 

Agree, thermal cutout. You can bypass it by connecting to pin 2. NOTE: This Is Dangerous.

ak

Thanks ak , ill be chicken and connect to pin 4.
Best regards.

 

Thanks ak , ill be chicken and connect to pin 4.

Agree.

On second thought, pin 2 might be intended as a test connection, to check the value of the cutout and the quality of its connections inside the transformer core.

ak