Help Convert Rotel Amp 220v to 110v? SEE PICS

[ted777ted]

Hi Guys, wondering if you could give me a hand here. I picked up an old Rotel RA-820 stereo integrated amp second hand. Unfortunately for me in the USA, it's wired for 240v mains. The instruction manual mentions that this amp ships with different voltages for different destinations. Can anyone take a look at at the pics and tell me if it is possible to wire the PT for 120v lines?


HERE IS THE LINK TO THE PICTURES
http://members.cox.net/ted007ted/jbl/rotel.html

The blue and white wires are the primary side of the transformer. No markings on the unit or the transformer as to what the taps are. I tried googling Bando but did not come up with anything. Also there is no switch on the back to select voltages. I know I could buy a step up transformer, but the idea of changing the wiring is much more attractive. I searched this forum and read all the posts I could find, but no luck. Any advice is grately appreciated.

Many Thanks,
Ted

[bocka]

If you are carefully you can measure the primary voltage taps with a multimeter in the AC range as the transformer acts as an autotransformer. Connect it to the 110V mains and measure where 55V appears. Resolder the main wire to that transformer pad.

[ted777ted]

Thanks very much for your help. It makes sense and I will break out the multimeter tonight and give it a shot tonight.

[young_pup]

Hi,

Did you manage to do it? I found the bando website:

http://www.bandohk.com/en

I'm trying to rewire an accuphase e307 from 100v to 240V!

Richard

[ted777ted]

Richard, I was able to convert the amp, listening to it now. You can not use the same method because you don't want to apply 240v at the 120v tap. Assuming that your transformer has multiple taps so it can be used at 120v, you can try this. Turn the unit OFF. With a decent multimeter, measure the resistance between the nuetral tap and the hot taps on the transformer's primary side (the side that connects to the wall socket). You should see resistance double as you go along the taps on the transformer. Then simply resolder the wire to the doubled resistance.

[young_pup]

Hi Ted

Thing is i can't plug the unit in can i? What happens if i plug a 110V unit into a 230V supply?

I'll get a multimeter and try what you said...so its not the little clips that need moving its the wires coming from the switch? Normally you move the little clips around on the busbar...see my post Accuphase E307 for photos.

Will try some things out today!

Richard

[bocka]

What happens if i plug a 110V unit into a 230V supply?

Probably the main fuse will blow. But additional damage is not uncommon. In this way never plug a 110V unit into 230V supply. Only the other way round will not result in a damage of the unit.

[young_pup]

Hi again

probably going to buy a step down transformer and try to rewire it that way!

its quite difficult...one mistake at 240V and its all over

Richard

[djQUAN]

you could plug it in a 110V outlet and measure where the 240V appears in the transformer taps and solder it there. basically the same method.

[young_pup]

Thats exactly what I'm going to try!!!!!!!

Many thanks!!!!!!!!!

I hope to reply back with my progress! If you check the photos on my post 'Accuphase E307 rewire' you can see the options!

Richard