i need tech help!! ( with schematics!!! )

In my opinion, if you're inexpirienced enough to not be able to read the schematics, it would probably be a good idea to have a qualified amp technician do the work for you. Better safe than sorry, you know.

 

Didn't we go through all this? Your amps power transformer has one 120V winding for its primary. To run this amp on 240V you need to replace the power transformer or use a 240/120V 1000VA step down transformer. There is nothing else to do! I doesn't matter how many threads you start on this same subject the answer remains the same.

Paul

 

+1

Not only is there the knowledge to read a schematic, soldering and all electronics work is a practiced skill. You would need a lot of practice to learn how to perform quality electronics work, tin component/wire leads, how to select solder, flux, inspect and clean your work when finished, all that jazz.

 

If you look at the file 350X.pdf. Down at the bottom left you will clearly see the AC wiring with a transformer connected labeled 100-120V transformer p/n 560007-120. Underneath you will see the alternate transformer labeled 220-240V Transformer P/N 560007-230. In order for your amp to operate on 220-240V you need to buy from SWR a transformer part number 560007-230. As you have been told time and time again that is your ONLY option.

Paul

P.S. Nobody that I saw called you stupid! Misguided yes - you bought an amp from the States that is not operable in your part of the world. I feel for you I truly do but no one can help you further. That SWR told you the transformer was tapped is unforgivable however we've all read of similar customer support foul ups.

If the transformer is a toroid you might be able to buy a replacement locally that would do the job. You will need to know the required voltages and currents involved in order to get a suitable match. This I fear is beyond your capabilities.

 

+1 I'd let a compete tech handle any amp surgery (working on equipment which uses lethal voltages) because my life is worth more than a repair bill--and so is the OP's!

OP, a good 110 VAC jolt will put you on your a$$--or worse.

A 220 VAC jolt will fry your a$$, period!

Please take your amp and its schematics to someone who can do the desired work safely.

--------

A side note: This recurrent voltage conversion issue which some TB members experience with the amps that they buy, can be avoided by selecting gear which supports international voltages--as a growing number of modern rigs do.

 

I don't know if the schematic can be trusted 100%. There is something fishy about the polarity of the bridge . If the OP knows what he's doing it's also possible to figure out if the transformer is multi tapped on the primary. There should obviously be multiple leads or connections on the primary side that he can check with a multimeter for continuity and resistance. They might look something like http://www.hammondmfg.com/5CHook.htm

If those don't exist then the transformer is not multi tapped. If they exist, then the schematics are no help either whatsoever since they show non-multi tapped transformers. The only way is to test it with a multimeter and then to do a disconnected voltage check on the secondary after rewiring to use the high voltage tap. It's also not too hard for an experienced tech to figure out the required replacement transformer since we know that the DC rails are 75 volts on each side and the power rating would usually be limited by the size of the original transformer. It's possible to get a higher current (larger) transformer as long as it will fit and the cooling system can handle the higher current capability.

 

To the OP: It seems to me that if SWR says the transformer is multitapped, then they should be able to provide you with the part number and specs for that particular transformer. Their techs should also be able to give you specific wiring instructions via email or fax.

Looking at a schematic which may or may not be specific to your particular amp, without seeing your amp, makes it difficult and probably unwise for us to advise you on rewiring your transformer.

 

Hi.

What Paul said. + whatever amount You find reasonable.

The shematics they sent You don't support that possibility.

Please don't make me kick myself for saying this, but if You take a pic of the transformer, from the primary side lugs, we can determine whether the PT is actually multi-tapped (which I doubt very much BTW).

Also, the serial number of the transformer will most probably tell what it actually is, but there's a 99% probability that it's the p/n 560007-120 and You're SOL.

None. The main one (350X.pdf) shows the 2 alternative (NON multi tapped) transformers like quite a few techs have already said.

Having the shematics and the bias procedure for a specific amp is always good, but there's a reason companies don't usually hand that information out freely. This instance is one of them.

Not really, if they included a "no distribution" note with the shematics. If they did, theoretically they can sue Your ass for distributing them. Fortunately not a likely scenario though.

And just for the record, I don't think You're stupid and I guess no-one else does either. You're actually very wise to ask before you act.

The fact that I agree with the other posters about this being well over Your head still remains the same though.

120V kicks like a small pony, painful but You'll most probably live.
240V kicks like a stallion, it hits You in the right spot or thereabouts and You're DEAD.

Regards
Sam

 

So you final;y followed the advice you were given! I'm pleased - sorry it couldn't work out the way you wanted.

Take care...
paul

 

I'm amazed none of us geniuses thought to have him use a step-down converter external to the amp?

I think his last post said that he did get it to work, just via a different route, technically.

 

Actually, Bassman paul suggested that ages ago.

The thing is, SWR seems to deny that, and claim that it can be done with no added parts.

The simplest thing to do is to count wires from the power transformer. Even better would be a picture.

If it has 5 wires, it's single voltage per schematic. If it has 7 wires, it may well be dual voltage.

The SWR schematic is totally unreliable......... I see one definite error (check hint above) and the power transformer thing may be bogus anymore, the schematic is dated 6 years ago. Most companies ditched the single voltage deal a long time ago, although some still have it for their cheapest units.

 

I must have missed Paul's suggestion when I first read through this thread when it first was posted. Sorry Paul! Definitely a good suggestion.

 

Hi everyone,

With the risk of looking like an idiot, I got a replacement tranny for my redhead. So I am converting to 240V from my old 120V us one. Now this tranny is for sure a multi-tap. Has six wires at the primary. I assume I just put the two 120V in series to make 240V and float the to 100V taps?

With the secondary there are taps for the board, filament etc. Now as they are AC I was assuming which way round the green and green wires for the filament goes doesn't matter? Same with the two violet wires, red etc?

May end up getting a pro to do this but it seems pretty simple compared to the electronics stuff I do, just I have never handled power transformers before.

Thanks in advance,

O.

 

If you are not sure get someone who does know to do it for you. In general your statements are correct however you are dealing with mains voltages here and your local electrical codes may need to be addressed. You could make your amp dangerous to use. Remember you have to change the power fuse to one half the size of the 120V one.

Paul

 

Thanks Paul,

will go and find an amptech I think. A bit embarrassing with a PhD in electronic engineering but like you say, mains is another game altogether,

Oliver.

 

I can read music pretty good too, but I wouldn't take a gig subbing for a symphony player!