• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Converting 220v input (European) to 110v (US) input

M

Mark Skubal

New Member
Anyone know a good place to buy a small replacement power transformer so I can convert the input power to 110v ? I bought a Toshiba sy-335 preamp and a Toshiba st-335 tuner from a party in Europe; they use 220v input. Or possibility can the input just be retaped from 220 to 110 without changing it?
 
Register to hide this ad
you will need to look inside and see how many wires go into the transformer on the primary mains power side ..post some nice pictures ..
 
Failing that you can buy on Ebay a first class step up / step down external transformer, I bought a 500w one for my Yamaha CR-1020 as it was 110v only and here in Australia they have 240v. I toyed with the idea of swapping out the internal one but even if I found one from a parts unit it would have cost a lot. And with a tuner and preamp you could get away with half the size I bought.
 
a funny thing is with both these i just looked at owners manuals as couldn't find service ones .both state 120v .
do they say 240v on rear panel ?
 
I could be wrong but a 28vac CT should give around 39vdc after the bridge rectifier with a 7.6vac winding would do it looking at the schematic?

Even the 7.6vac winding would not be necessary if you swapped out the meter lamps for Led's?

toshiba_sc-335_stereo_amplifier_sch.pdf_1.png
 
Last edited:
BinaryMike said:
You need +/-39VDC, so the xfmr secondary has to be near 56VCT.
Click to expand...
Can you dumb this idea down a little? I'm a little familiar with a current transformer(a round transformer) are you saying instead of REPLACING the the existing 220v power transformer, I can add a CT to the circuit? Could you draw a diagram of this circuit with placement?
 
Mark Skubal said:
Can you dumb this idea down a little? I'm a little familiar with a current transformer(a round transformer) are you saying instead of REPLACING the the existing 220v power transformer, I can add a CT to the circuit? Could you draw a diagram of this circuit with placement?
Click to expand...
 
This 12 buck device from the bay will supply both the 5W preamp and the 9W tuner with the proper voltage.
http://www.ebay.com/itm/110V-120V-t...644903?hash=item20e20fe0e7:g:gLIAAOSwVFlT~u5b

I only looked at one cheap device. Lots of options.

If you go the route of the transformer, if there are AC outlets on the back of the units, don't use them unless the transformer can supply the power needed for the additional devices. The manuals are for US units on HFE and show convenience outlets but the high voltage units might not have that.
 
Mark Skubal said:
Can you dumb this idea down a little? I'm a little familiar with a current transformer(a round transformer) are you saying instead of REPLACING the the existing 220v power transformer, I can add a CT to the circuit? Could you draw a diagram of this circuit with placement?
Click to expand...

CT stands for Center Tap which is part of the transformer, you would replace the whole transformer with one that's 110v primary and is 56v CT with 28v, 0, 28v secondaries.

But this is working with mains voltages and can be dangerous and/or deadly, I would go with just buying a step up transformer and its plug and play.
 
HypnoToad said:
CT stands for Center Tap which is part of the transformer, you would replace the whole transformer with one that's 110v primary and is 56v CT with 28v, 0, 28v secondaries.

But this is working with mains voltages and can be dangerous and/or deadly, I would go with just buying a step up transformer and its plug and play.
Click to expand...
Thanks for the great input, I'm an electrician with experience working with transformers, just not engineering usable options. I'm getting a quote from "Pacific Transformer" Corp. For a 120/56vac ct transformer with an additional 6.7vac output for the meter light circuit. I'd like to pursue this cleaner option if practical money wise.
 
How about a picture of your preamp inside, not the web one. The picture from the web has the original transformer removed, and another one mounted inside. There is only one primary and one secondary on that unit.
Second, the schematic in post 7 is of the POWER AMP, not the tuner or preamp. So the transformer mentioned in posts 7, 8, and9 won't help you (unless you have the amp, also,)
Third - Since you have both tuner and preamp to convert, it seems a lot simpler to use a step-up transformer for AC for both both units.
Good luck.
 
sregor said:
Second, the schematic in post 7 is of the POWER AMP, not the tuner or preamp.
Click to expand...

Good eyes, didn't see that.

Here is that part of the schematic for the SY-330, just can't find the SY-335 and it's single winding probably round 15vac, but don't quote me.


Toshiba_zpsrccdxba8.png
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom