uk transformers

[cigarboxblues]

I was wondering please,poss another silly newb question but,  if you can tell me quite a straight awnswer to a question guys.
as some of you may know i bought a amp chassis ,now it all went ok worked and so on.
so next thing is iam wanting to use the chassis and 2 transformers ,they are based on 4/5 watt.
now iam wanting to go ahead and do a project,but well im sat looking at schametics and well projects.
and well they all seem to be based around the american transformers. ive seen a nice looking project
for beginners over on ax84 obviously id need to go up on chassis.or well then theirs the champ.
and so on and well i feel ive learnt a bit today going through the amp ,but now well i would like to
convert ,or well have ago thanks chaps 

[JayB]

As long as they got the proper primaries for the wall voltage over there, you should be fine. If not, you will have to find the transformers.

[Dave]

The big difference between American transformers and Brittish ones is only going to be the line voltage they are designed to receive.

Better said, a Brittish transformer will be set up to receive 220 volts on the primary side and will give X on the secondaries.

If X is equal to whatever American amp you want to build, then you're all set.

Dave

[cigarboxblues]

many thanks guys ,that clarifys that for me anyway .
cant be to over cautious i suppose but easier on the mind knowing thankyou 

[Shrapnel]

Just for the record, Cigar, Output transformers won't matter a bit, just as long as input and output impedances are the same. (And provided you don't have the garbage Dagnall turned into before they closed up shop, permanently.)

[cigarboxblues]

yes i beleive so ,they are matching pair.
dagnell i think i might have to do a little research on that one ,is that the manufacturer lol,
sorry i cant say iam overly clued up on some terms yet .
one thing i noticed from the power tranny is it has 2 power switchings via a old fuse.
then fed to the on off switch knob i intend changing to a toggle switch.
and well iam assuming that only the side its switched to via this fuse is in use.
this leading me to the fact or thinking the other isnt required in the on of switch circuit.
i think iam learning more daily lol ,not doing much else.
think ive found a hobby to test the old brain matter now lol 

[FYL]

The big difference between American transformers and Brittish ones is only going to be the line voltage they are designed to receive.

There's an even bigger one: US PT's are designed for 60 Hz, UK models for 50 Hz. If the core isn't properly sized, the PT will vibrate, hum and overheat. You need at leat 12% more lams for 50 Hz, heavier, bulkier, more expensive.

[cigarboxblues]

hmm i really am fighting an up hill battle to think ,i can pull a little amp of aint i.
suppose a kits the only way ,paint by numbers i think ,or back to school but at my age i think not.
back to the books 

[Dave]

No, if those are UK transformers and you are in the UK, then you are perfectly fine.

FYL,

I think I'd rather have a transformer do a little shaking than to zap my 6V6's with 800VDC. Maybe I'm crazy, but I'm going to stick by my statement that the big problem is the primaries.

Either problem keeps us from operating an American transformer is UK or vice versa.

Dave

[HotBluePlates]

one thing i noticed from the power tranny is it has 2 power switchings via a old fuse.
then fed to the on off switch knob i intend changing to a toggle switch.
and well iam assuming that only the side its switched to via this fuse is in use.
this leading me to the fact or thinking the other isnt required in the on of switch circuit.

I'm not exactly sure what you're describing.

However, it sounds a lot like the way Marshall wires their power switch. So your power cord has a hot, a neutral and a ground. The hot and neutral are connected from mains to the power transformer primary, and supposedly the hot wire is the one that's "live". So a lot of older equipment and a lot of modern american stuff just has the switch on the hot wire.

The catch is that when the switch is closed, current flows through both wires. The real issue at hand is what happens when there is a failure. Assuming perfect wiring, if the fuse blows or the switch is opened, then the hot wire is disconnected and does not get farther into the amp than the fuse or switch. But if the outlet wiring is incorrect, the entire circuit from the wall through the power transformer to the "safe side" of the fuse or switch is now live. No current flows because there is not a complete circuit, but it presents a shock hazard.

Further, assuming wrong wiring and a failure that shorts from the power transformer primary to the chassis, on the "safe side" of the fuse and switch. Now the switch can be off, the fuse can be pulled, but the entire amp circuit is electrically powered, the entire PT primary circuit is completed, and the failure could result in shock, burnt parts, and in the worst-case, your house burning down and you dead.

I don't know that it is part of the EU electrical code, but it certainly seems required in the UK and EU to switch both sides of the mains cable to gaurantee safety. I have seen rare cases where both sides of the line were fused as well, to further remove chance.

[cigarboxblues]

yes iam realising my mistake in what i posted ,and since looking further at how it switching
on the tone control at how the power makes that circuit ,thankyou simon

[jhadhar65]

>I don't know that it is part of the EU electrical code, but it certainly seems required in the UK and EU to switch both sides of the mains cable to gaurantee safety. I have seen rare cases where both sides of the line were fused as well, to further remove chance.

I think switching hot/neutral is required if you're going to slap CE on there somewhere.  Regardless, that's how I do it on nearly every application anyway.  I skip it on some radios and stuff by just switching what should be the hot side, but I only do that when I need to use a switching scheme consistent with OEM for front panel aesthetics.  I always match those with a new polarized AC cord.

If you're replacing a switch anyway, get a double pole and be done with it for all the reasons HBP suggests.

[FYL]

Maybe I'm crazy, but I'm going to stick by my statement that the big problem is the primaries.

This isn't a problem: you should of course use the right iron with the right 240V primaries, but this isn't enough, the PT should be designed for 50 Hz operation.

[HotBluePlates]

Maybe I'm crazy, but I'm going to stick by my statement that the big problem is the primaries.

This isn't a problem: you should of course use the right iron with the right 240V primaries, but this isn't enough, the PT should be designed for 50 Hz operation.

Now, now girls... you're both pretty!! 

Each of you is on to the right thing; and if the end-user is not very tech-saavy, then the "easy solutions" we take for granted aren't obvious and won't be used, possibly resulting in a very expensive lesson.

You don't wanna just slap an american transformer in an amp intended for UK operation, but then again, there are transformers available by the same folks who make the american transformers that can swallow UK mains voltage and frequency.

If you're unsure, and an american part is specified, just ask on the forum here "what UK transformer for this circuit?" That'll take the guess-work out.

[Dave]

FYL is certainly pretty, but I am irresistorable.

Dave

[cigarboxblues]

yes i realise where i have overlooked the switching in the first instance
after i looked at the piece after i posted i see where it plays its part.
and well makes me think then is it nessarary to have a throw switch on or leave
as is on the pot.and sorry didnt mean to start a bad thread or post guys.
regards the transformers,im a sucker for junk and i get fiddling.
i know you cant make a silk purse out of a sows ear,and ive lots to learn in anycase. simon an thanks

[Dave]

Hey FYL,

Which is the bigger problem.........

The Fer Du Lance dangling from my rump........

or the fact that he is detoxing from a heroine addiction and is seazing violently?

Dave

[cigarboxblues]

also i havent mentioned i dont believe using an american transformer in the uk .
i asked if the uk ones i have will work on schametics that i come across.
iam not looking to cause a rift just genralised question .
iam not looking to make costly mistakes ,as in the reason for my post in the first instant.
and well i will leave it at that .and well iam sure as other have to do learn alone.
iam sure we all started somewhere really ,and well not all technical genius.
iam intrested in guitars and well hopefully 1 day i might build a tube amp thats all .
so no need to argue over the topic really .
ad as for saftey well i think thats why i asked the question to begin with. thanks anyway

[HotBluePlates]

Don't sweat it Simon. I'm sure everyone is alright...

[Dave]

We're just fooling around. No problem.

The snake thing was intended to be funny.

"A little good hearted disagreement can sometimes lead to collateral and more effective solutions" Dave 30 Apr 2010

Dave

[cigarboxblues]

lol no sweat pref not to get into a forum disagreement.
i will go with a uk kit with a paint by numbers
or stick with boring solid states an make do 

[Dave]

Never be content to make do. Yammering back and forth flips brain switches and answers questions.
This forum boasts a proud sense of brotherhood and there are no enemies here, except for FYL who is definately an imposter. 

Dave

[FYL]

You don't wanna just slap an american transformer in an amp intended for UK operation, but then again, there are transformers available by the same folks who make the american transformers that can swallow UK mains voltage and frequency.

I've seen many US-made export PT's designed for 60 Hz and 220/240V primaries. Small cores, M19 lams, crappy. But yes, there are many 50/60 Hz versions available from American manufacturers.

Here are two equivalent PT's from Hammond - 600V C.T. @ 115ma. 5V @ 2A, 6.3V @ 3A. The small one is a 272BX (117V/50 Hz), it's much larger bro a 372BX (world voltages, 50/60 Hz).

[JayB]

one thing i noticed from the power tranny is it has 2 power switchings via a old fuse.
then fed to the on off switch knob i intend changing to a toggle switch.
and well iam assuming that only the side its switched to via this fuse is in use.
this leading me to the fact or thinking the other isnt required in the on of switch circuit.

I'm not exactly sure what you're describing.

However, it sounds a lot like the way Marshall wires their power switch. So your power cord has a hot, a neutral and a ground. The hot and neutral are connected from mains to the power transformer primary, and supposedly the hot wire is the one that's "live". So a lot of older equipment and a lot of modern american stuff just has the switch on the hot wire.

The catch is that when the switch is closed, current flows through both wires. The real issue at hand is what happens when there is a failure. Assuming perfect wiring, if the fuse blows or the switch is opened, then the hot wire is disconnected and does not get farther into the amp than the fuse or switch. But if the outlet wiring is incorrect, the entire circuit from the wall through the power transformer to the "safe side" of the fuse or switch is now live. No current flows because there is not a complete circuit, but it presents a shock hazard.

Further, assuming wrong wiring and a failure that shorts from the power transformer primary to the chassis, on the "safe side" of the fuse and switch. Now the switch can be off, the fuse can be pulled, but the entire amp circuit is electrically powered, the entire PT primary circuit is completed, and the failure could result in shock, burnt parts, and in the worst-case, your house burning down and you dead.

I don't know that it is part of the EU electrical code, but it certainly seems required in the UK and EU to switch both sides of the mains cable to gaurantee safety. I have seen rare cases where both sides of the line were fused as well, to further remove chance.

I'm not a big residential or commercial electrician. If you measure that neutral side, there is voltage on it and I have measured 60V right now. My question is, where does that wire go?  

[FYL]

Which is the bigger problem.........

"Look Dave, I can see you're really upset about this. I honestly think you ought to sit down calmly, take a stress pill and think things over."

 

[FYL]

This forum boasts a proud sense of brotherhood and there are no enemies here, except for FYL who is definately an imposter. 

"I've just picked up a fault in the AE-35 unit."

[Dave]

Those last two posts really made me laugh.
All is forgiven.

Dave

[HotBluePlates]

I'm not a big residential or commercial electrician. If you measure that neutral side, there is voltage on it and I have measured 60V right now. My question is, where does that wire go?

I'm not an electrician either. I have done some (probably illegal) wiring work before, though.

The hot wire should be live. In theory, you should measure 120vac from this wire to the ground socket. The neutral should measure 0v to ground. It is bonded to ground at the breaker box.

However, there are a variety of reasons why neutral might not measure 0v to ground. I'm surprised you measure 60v, unless there's something going on that I don't know about (possible). Normally, it's more like a volt or 3, due to either wire resistance or a poor quality bond to ground.

There are some real electricians on here who can say for sure.

[PRR]

> If you measure that neutral side, there is voltage on it and I have measured 60V right now.

60V to where??

Use the wall-outlet U-ground pin as reference. (in the US/Canada) One slot will be near 120V. The other slot will be "near zero". Under 5V. In a well-wired house with no big loads running, often under 1V. If that's not what you got, consult an electrician!

Now go around to inside the amp. On some amps, if you disconnect the wall-ground, the chassis will float to half the supply voltage, around 60V. This is because there are two caps, from chassis to each power wire. The cap size is picked so that if you put your body across the 60V (please don't!), it loads-down the cap leakage and you do not get a fatal shock. Your meter is a much lighter load than your body and will show nearly the full 60V.

But this will not happen if the amp is properly grounded to the wall-outlet. Back in the '60s'/'70's I had to deal with gear that bled 60V shockage all over the stage. Such gear has not been legal in a long time.... not for "New", and anything "old" should be updated for your safety.