Accuphase A-48S

@imhififan 

Would it be possible to convert the A-48S from 100V to 230V given that it has a soft start #716-0962-01 requiring a replacement transformer?

Could you advise what the wiring changes would be to the transformer to convert the primary winding to 230V

Thanks, Andy

@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.

Thanks @imhififan 

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

Also, 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.

Not being experienced, how would I go about finding a replacement transformer?

Thanks in advance for any help you can give.

Cheers, Andy

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.

Thank you. Makes sense. I was going off the specs on the NMD website which says that the transformer is a 3 pin input 4 pin output.

https://www.nmd-trans.co.jp/p2_PinTypePowerTransformaer.html

HTP-35-12 transformer.

Looks like there are a lot of transformers available that will fit this package format from various manufacturers with a good selection of output voltages.

I'll continue to use my amps with a step down transformer for the moment, but think I will have a look at converting to 230V sometime in the next few months as it sure would be more convenient.

Has anyone measured the output voltages from the transformer, do you know?

Cheers, Andy