step down transformer for US stereo

[gamb00ler]

I have a 120v surround sound system that we packed from USA with our household goods.

I brought it because I figured selling it and buying a replacement wouldn't be efficient and the 20' container had room (barely 😳).

 

It's time to set it up so I'm looking for advice on a transformer for 230V to 120V.

 

The amp specs. say 540W and the powered sub-woofer requires 135 for a total of around 700W.

 

I have found a transformer on Lazada rated @800W.

 

Should that be OK or should I leave a little more headroom and get a 1KW transformer?

Are there different types of transfomers available?  If so, what is the best type for a sound system?

 

[Crossy]

I'd give it a bit more room although I doubt you'll ever run anywhere near maximum output.

 

Does your unit specify only 100-120V on the rating plate? Many modern systems have universal "100-240V" power supplies.

[impulse]

Don't skimp on your transformer unless you enjoy a loud 50Hz hum.  I'm not going to claim to be an expert, and I offer no advice on what type of transformer to buy.  (Except that there's cheap ones and better, shielded ones)  But I had a horrible hum when I put a US stereo on a transformer in China, where the power is the same 220V, 50Hz.  Even worse when played loud and I suspect the transformer was clipping.

 

You may wanna go by Fortune Town in Bangkok or one of the other markets that sell high end audio equipment and get their advice.  Ban Mo electronics street market near Chinatown is another good place to look for sound equipment.

 

 

 

[gamb00ler]

1 hour ago, Crossy said:

I'd give it a bit more room although I doubt you'll ever run anywhere near maximum output.

 

Does your unit specify only 100-120V on the rating plate? Many modern systems have universal "100-240V" power supplies.

Sadly it's a North American model with no ability to select the input voltage.  The amp and sub-woofer are the only 120V items we brought over.

 

Maybe I'll just borrow the stepsons sound bar to see if that's enough improvement over the small and back-facing TV speakers.

[RayWright]

A mate of mine was in the Frank Zappa Road-Crew when he toured AUS back in 1976. His warm-up routine included playing along to various pre-recorded guitar licks &  solo's he had on cassette tape for his USA 'Getto Blaster' which he use to plug into the Australian mains. However Australia was 220V, the Blaster was 110V.

His comment was, "no problem, I'll just play faster".

 

[bluejets]

11 hours ago, gamb00ler said:

Sadly it's a North American model with no ability to select the input voltage. 

 

That may be however, if you look on the model details sticker/plate there might be allowance for "automatic" range of input voltages.

Especially if the power supply is smps as most from the last 15 -20 years would be.

Name plate would show input as example 110-220v ac.

 

Failing that, get a new unit....cost and availability of a decent step down transformer would make it impractical.

[gamb00ler]

8 hours ago, bluejets said:

That may be however, if you look on the model details sticker/plate there might be allowance for "automatic" range of input voltages.

Especially if the power supply is smps as most from the last 15 -20 years would be.

Thanks for your post.

 

I thoroughly checked the unit's capabilities before deciding to bring it over from US.  I don't think I messed it up.

 

[Crossy]

It's worth popping the lid off, it may well have the dual-voltage transformer anyway.

 

[gamb00ler]

Just now, Crossy said:

It's worth popping the lid off, it may well have the dual-voltage transformer anyway.

I should be able to manage that!  

[Crossy]

10 minutes ago, gamb00ler said:

I should be able to manage that!  

 

Post decent photos.

 

[gamb00ler]

4 minutes ago, Crossy said:

 

Post decent photos.

 

 

[gamb00ler]

There is a label on the side of the power supply but it appears to only give the part number.  It looks to be easy to replace the power supply.  Maybe I can just buy the power supply part that they use in the model sold for Asia.

[impulse]

I don't know how far the OP wants to take this, but if it were me, I'd take the unit down to Ban Mo electronic street market near Chinatown and I'd bet someone can rejigger the power supply to take 220/50. 

 

I'm always amazed when I wander down a new alleyway there and see someone rewinding a cheap fan motor or resoldering components on stereo circuit boards.  One of the things I love about Thailand, where labor is cheap enough to actually fix stuff instead of binning it.

For something at that complexity level, it would be good to bring a Thai speaking friend to translate.  And let them negotiate, they've been haggling prices since they learned to talk.

 

Edit:   Caveat... Ban Mo isn't for everyone, but anyone with an interest in DIY, especially electronics and "maker" stuff, it's like a toy store.  But it may take time to find exactly what you want.  Especially if it's in the bowels of the buildings surrounded by the street market.  I love the place.

 

[gamb00ler]

1 minute ago, impulse said:

I don't know how far the OP wants to take this, but if it were me, I'd take the unit down to Ban Mo electronic street market near Chinatown

I live in Chiang Mai and my efforts to find somebody that even seems to have a clue how to fix it have so far yielded nothing.

[impulse]

Just now, gamb00ler said:

I live in Chiang Mai and my efforts to find somebody that even seems to have a clue how to fix it have so far yielded nothing.

Que Bumero.  (that's Spanglish).  I would hope there's a similar market in Chiang Mai, and someone may come along and chime in.

 

[OneMoreFarang]

23 hours ago, gamb00ler said:

The amp specs. say 540W and the powered sub-woofer requires 135 for a total of around 700W.

 

I have found a transformer on Lazada rated @800W.

 

Should that be OK or should I leave a little more headroom and get a 1KW transformer?

If you don't play full power than you will come nowhere near the max of 700W. Likely you won't even use 100W most of the time.

800W should do the job but it never hurts to have some more headroom. 

[OneMoreFarang]

As far as I know Americans us 60Hz and in Thailand we have 50Hz.

It seems for some equipment that is not a big deal, and for others it's a problem.

 

AC Voltage conversion with the same frequency (Hz) is easy and relative cheap.

AC Voltage conversion with frequency conversion is a lot more complicated and expensive to do - if done right and with lots of power. 

[gamb00ler]

I thought all the internal circuitry of an audio amplifier uses DC power.  If that is correct the frequency of the input AC should not matter.

 

But.... I know so little about electronic things, that my opinion is of little value, even to me.

 

 

[gargamon]

47 minutes ago, OneMoreFarang said:

800W should do the job but it never hurts to have some more headroom. 

Yes it does. A transformer will consume electricity even if it's doesn't have anything connected to the transformed side. The larger the transformer, the more electricity it will consume. 

[Crossy]

1 hour ago, gamb00ler said:

There is a label on the side of the power supply but it appears to only give the part number.  It looks to be easy to replace the power supply.  Maybe I can just buy the power supply part that they use in the model sold for Asia.

 

If you can get that as a spare part that would be ideal.

 

[Fruit Trader]

The Onkyo SR-606 rev-04 schematic shows voltage selection.

 

[dddave]

23 hours ago, gamb00ler said:

Maybe I'll just borrow the stepsons sound bar to see if that's enough improvement over the small and back-facing TV speakers

An excellent alternative are Edifier "active" speakers, sold locally on Lazada.com.  These are "powered" bookshelf size speakers, that is, they have their own built-in amplifier and require no outside amp or pre-amp.  I use 1280 DBs on my bedroom TV and R2000DBs on my living room TV.  Excellent sound.  many YouTube videos about them.  
https://www.lazada.co.th/catalog/?q=Edifier+speakers&_keyori=ss&from=input&spm=a2o4m.home-th.search.go.11257f6dMqsgFs

[lopburi3]

Another factor to consider - if they made this special for US market the built in transformer(s) would be the reason (cheaper to make 60Hz than 50Hz) so even if you use pre-transformer the built in transformer(s) may overheat.

[Prubangboy]

On 11/6/2023 at 4:50 PM, impulse said:

I had a horrible hum when I put a US stereo on a transformer in China, where the power is the same 220V, 50Hz.  Even worse when played loud and I suspect the transformer was clipping.

 

 

 

 

 

This happened to me too. I tried 3 diff transformers, no luck. I also tried a power line conditioner with the transformers -in vain.

[Fruit Trader]

40 minutes ago, Fruit Trader said:

The Onkyo SR-606 rev-04 schematic shows voltage selection.

 

 

Update I forgot to mention -

 

There is a chance your receiver contains the dual voltage transformer but has the voltage selector omitted for the US market. An electronics repair shop can check if your transformer is dual voltage but hard linked at 120V.

 

[bluejets]

On 11/7/2023 at 5:31 PM, gamb00ler said:

I don't think I messed it up.

No, you have it correct.

Now as the label shows, better if you come from Asia Pacific.............

 

Anyhow, something to consider, given the input power is a conventional transformer (must be old unit)...consider as I have done in the past in a squeeze.

Some will complain like a stck pig, however..........I have in the past used a triac style dimmer of appropriate VA rating on transformer primary to control output.

Note that this will NOT work on smps units.

Given the output of your device is transformer / rectifier smooth to DC, perhaps no problem.

It might, given the fact that it is phase control, perhaps create noisy environment for an audio amp.

 

Try it at your own risk though as you would not have any control/monitoring equipment available or the knowledge to do it.

 

Then again you could also series up a 550W incandescent bulb...........shock horror.....

 

If it was me, I'd cut my losses and simply chuck it and buy a new unit to be honest.

[gamb00ler]

6 hours ago, bluejets said:

If it was me, I'd cut my losses and simply chuck it and buy a new unit to be honest.

For the cost of my time (I'm retired, so == 0) and a few electrons... I'm trying to connect with Onkyo Thailand via Facebook.

 

Hopefully they can point me to a place to order parts such as a power supply for the Asian model of my receiver.