@leecc73

Thanks for the photos.

I think the brown and blue cables are "live and neutral" come from the AC mains IEC socket, the small transformer is connected to it via a resettable fuse (F1), and the K4 is connected to the front panel power switch.

When the front panel power switch engaged, RELAY1 energized and close the contacts to power the main transformer.

I believe Accuphase made three versions of this board for 100V, 120V and 220/240V mains. If you want to convert to different mains voltage, a new board or install a small transformer with correct primary winding for the applied voltage is needed.

Thanks for the analysis, do you know what kind of miniature transformer is it?

If i turn it on with higher voltage, will it burn? or the fuse will gone.

or i just simply not able to turn on?

what is see the red wire kind of link (by pass) from this board and go over to the next board which allow for the main transformer to have the voltage change.

i remove the board out.

Here what i understand, K2 input (brown) will switch to K1 (red) after relay turn on once power button press in and direct the current to sec board .

Relay is 18VDC power by transformer (from K2) thru smd Z622.

Im not sure what is z622? , i assume its rectifier to supply 18VDC to relay. or any double voltage will damage the z622?

Sorry, I don’t know what kind of miniature transformer is it. Measure the size, lead spacing and the output voltage and see if you can find a replacement for 230V.

If i turn it on with higher voltage, will it burn? or the fuse will gone.

or i just simply not able to turn on?

The fuse (F1) will trip open circuit if connected to higher voltage, it will reset itself when that voltage removed. So it’s unable to turn on at all!

what is see the red wire kind of link (by pass) from this board and go over to the next board which allow for the main transformer to have the voltage change.

You can remove F1 ( just to be safe) and bypass the RELAY1’s contacts to allow the main transformer to have voltage change. However, the front power switch will be bypassed as well! You also need to check where is K3 connected to and see if it can work without power supply to this board.

Relay is 18VDC power by transformer (from K2) thru smd Z622.

Im not sure what is z622? , i assume its rectifier to supply 18VDC to relay.

I believe D3 (Z622) is a full bridge rectifier.

BTW, perhaps you can try remove F1 and add a small transformer with 120V primary in series to the existing transformer primary winding to make it work for 220V mains.

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.

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.