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

Discussion in 'Amps and Cabs [BG]' started by JazzMarius, Jul 22, 2009.

  1. hy guys. well, i want to convert my SWR 350x from 110V to 220V and after a bunch of emails and A GREAT SUPPORT from the guys from SWR/FENDER i got all the info i need, just that i don't know how to read it.

    that's where i need your help.

    they say this transformer is multitaped and they gave me the schematics to "switch the wires" to give me 220V.

    i have this schematics and i can't read them. i mean, i can but i can't understand them. can u guys explain me how to do it? ( e.g: red wire goes there, green , there )

    i can take pictures too.

    here u have the schematics, but i don't know wich one is the one with the conversion.

    i think is a lot of good info that u could also use for yourself.

    this schematics are SWR's property but since THEY GAVE THEM TO ME!!!! they are mine now :)

    wait for your help!



  2. RickenBoogie


    Jul 22, 2007
    Dallas, TX
    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.
  3. BassmanPaul

    BassmanPaul Inactive

    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.

  4. Hookus


    Oct 2, 2005
    Austin, TX

    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.
  5. they wrote me that I DO NOT NEED A NEW TRANSFORMER!! they say i just need to swich the wires, because it's a multitape transformer!!!!!

    i am not that stupid you know?

    i do know how to read schematics, but not that good at it. i studied electronic some time ago. i am very good at soldering and electronic stuff, just need a lil help here!!!

    i apreciate for your help but in the other thread i didn't know that the tranny was multitape so, that is A DIFFERENT subject.

    i need help! i do not need "u can't do anything" kind of advices.
  6. BassmanPaul

    BassmanPaul Inactive

    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.


    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.
  7. MIJ-VI

    MIJ-VI Inactive Supporting Member

    Jan 12, 2009
    +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.
  8. WingKL


    May 12, 2007
    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.
  9. 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.
  10. 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.

  11. wow! i forgot this thread!

    well, a very wise reply Sam.

    seems like the amp is working fine right now. no noise, no issue at all! i really don't know what happened!it must be a divine miracle!

    well, my amp is fully working right now and it sounds great! grind, deep, full! very funk-like.

    they didn't include "no distribution" in the emails, so that saves my ass i believe :D!

    i use the amp with a step down converter and, problem solved!

    thanks for ur support and replies!!
  12. BassmanPaul

    BassmanPaul Inactive

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

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

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    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.
  15. 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.
  16. like i told paul, i always had a step down converter.i wanted to convert it to 220 cause people of SWR told me that is possible an easy to do. i asked them for the transformer and the people of "mercury transformers" (Patrick Selfridge is such a gread guy!!!) sayd that SWR won't let them sell that transformer.
    i emailed again SWR and they told me it's multi-tape, they gave me the schematics ( in wich i didn't see what Ed Treat was telling me ). so, end of story.

    my problem was a noise ( i uploaded a clip ) that is gone now.

    so thanks for ALL your support and help and kindness!!
  17. diamondgeeza


    Oct 15, 2009
    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,

  18. BassmanPaul

    BassmanPaul Inactive

    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.

  19. diamondgeeza


    Oct 15, 2009
    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,

  20. :rollno::rollno:

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