Accuphase A-48S

@foolishman ,

Thanks for the photos, this time Accuphase is using a PCB instead of terminal block like before. Its connection method is still the same.

Looks like your friend already understands how these connectors work! Simply swap the positions of the black and yellow wires and swap the positions of the brown and orange wires to convert the power transformer primary winding from 100V to 120V.

On the #716-0962-01 board you will need to replace the small 100V transformer with a 120V one, or simply use a resistor to drop the input voltage.

IMHO, Accuphase products are certainly state of the art in terms of build and design, and if pricing was more affordable outside of Japan, I think more Accuphase enthusiasts would be able to enjoy it.

there's another way to convert to 120V, which is to swap the positions of the orange and yellow wires and swap the positions of the brown and black wires. Do you think it is OK?

Yes, both the 100V and 120V setups have the two primary windings in parallel, swapping the position of the orange and yellow wires and swapping the position of the brown and black wires should also work.

@andyf

Convert 100V to 230/240V, in addition to replacing the standby circuit transformer on #716-0962-01,

1. You will also need to find out which wires belong to which set of primary windings using an ohmmeter.

2. Remove jumpers J1 and J3 and install jumper on J2, change fuse on board #716-1364-01 from 10Amp to 5Amp.

just what would I install on J2, as it only has a single tab.

716-1374-01 is a soft start resistor board. Based on my previous experience, two sets of resistors are connected in parallel via J1 and J3 (100/120V setting), and two sets of resistors are connected in series via J2 (220/240V setting).

I believe that the standby circuit transformer has 3 pins on one side and 4 on the other. Does this suggest that it may be a center tap so can accommodate both 100V and 230V? It just needs wiring up differently.

Sorry I don’t have an A-48S in front of me, I just based it on the photo provided by @foolishman, if the transformer does have a multi-tap primary winding, that would make voltage conversion much easier!

Can you post front and back pictures of your #716-0962-01 board?

how would I go about finding a replacement transformer?

This is the real challenge! Measure the secondary winding voltage, transformer size and its pin spacing, search for 230V versions on Digikey, Mouser, etc.

@andyf 

Thank you for providing the transformer spec. Sorry, I don't know the output voltage of the transformer, maybe @foolishman  has measurements.

However, I remember there was a post from an old thread mentioned that the relay was a 18VDC relay, so I'm guessing the output voltage of the transformer is probably about 13.6 to 14V.

If you decide to convert the voltage to 230V, please post your findings and some pictures of the voltage conversion, I'm sure Audiogon forum members who want to do something similar will find your post helpful and appreciated.

I have some free time tonight, so let’s discuss some details on how to connect the transformer to 240V.

1. Remove all the six transformer primary winding wires from the circuit board.
2. Use a multimeter to perform a continuity test to confirm which wires belong to which primary winding.
3. Connect the transformer primary winding wires as shown below.