US 110v plug power lead mods

SunDevil

I have a US 110v on the way and it comes hard wired to a US 3 pin plug

I have a step down transformer and for other 110v amps with a male IEC connector on them, I just plug into that and I have an obvious white IEC lead connected to the transformer to avoid dramas.

The question is what to do with this new amp?

I don't want to fit a male IEC to the chassis or fit a UK plug and mis-connect in error, so I'm thinking the options are

1) Cut the plug lead to 1ft and fit a male IEC on the lead
2) replace the original lead to the switch with a new 1ft lead with male IEC plug
3) A better option...?

What would you fine gents recommend?

ICBM

Does your stepdown transformer not have a US socket on it? If not it would be best to get one with one.

Anything else and sooner or later you will probably plug the wrong thing into 240V...

SunDevil

..it does, but I'm not too mobile (back and neck), so I'm setup so the white ICE is 110v, the blacks are 240 and I don't need to get to the sockets, just to waist level.

I don't know if the new amp (Alessandro Doberman) has a multi tap PT on it, but either way, it will be much more practical to use the existing leads

ecc83

ICBM might have had a different experience but I had several instances of a 110V amp being plugged into 240V and the only casualty was a fuse. This was for VALVE amps and nothing smaller than a 20 watter. Solid state amps blew regulators.

So Baz, I think so long as your wiring scheme is safe and limited to YOUR place, go ahead. If the worst happens it is not like to cause final amplifier death.

Dave.

ICBM

ecc83 said:

ICBM might have had a different experience but I had several instances of a 110V amp being plugged into 240V and the only casualty was a fuse. This was for VALVE amps and nothing smaller than a 20 watter. Solid state amps blew regulators.

So Baz, I think so long as your wiring scheme is safe and limited to YOUR place, go ahead. If the worst happens it is not like to cause final amplifier death.

I've seen a few where the power transformer has died as well, even with the correct fuse value in. I wouldn't risk it.

SunDevil said:

..it does, but I'm not too mobile (back and neck), so I'm setup so the white ICE is 110v, the blacks are 240 and I don't need to get to the sockets, just to waist level.

I don't know if the new amp (Alessandro Doberman) has a multi tap PT on it, but either way, it will be much more practical to use the existing leads

In that case probably the best solution is to have the amp fitted with an IEC power socket. This is still risky if the amp ever goes out of the house though - since someone else could plug in a standard UK mains cable. This is exactly how one of the amps with a blown PT was done...

SunDevil

Thanks Gents, so I think I'll look to replace the whole power cord with a new one that has an IEC14 at the other end - that way I can always revert it should my needs change or I want to make it original to move on.

I've pasted a gut shot below - looks like the positive goes to the OT, the negative to the fuse and the earth has it's own grounding bolt - looks pretty straightforward, but anything I should be aware of?

http://i1381.photobucket.com/albums/ah232/SunDevilarker/Pedals 2017/Doberman01_zpsosqds8t5.jpg

Looking at the PT, it looks like it might be mutli-tap? ..if it is, is it just a case of reconnecting the mains wire to the OT to the correct lug?

Baz

ICBM

I can't see clearly enough - can you take a better pic of just the PT?

If not, make black the live and white the neutral, for correctly having the fuse on the live side. It looks like the 'death cap' is connected to the white, so that would also be safer, but it's best to remove it.

DJH83004

Can you post a close up of the Mains transformer to see what taps are available, if the neutral is going straight onto the fuse, then the live should go to the mains on / off switch and be nowhere near the OT (output transformer?) - the B+ (DC volts will connect to the centre tap of the OT primary winding, probably via the standby switch and separate fuse if one is fitted. 

SunDevil

Gents - thanks for the input - all makes sense

The amp is currently in transit to me (these are the seller's pics), so I can't improve upon these right now, but I'll take some better shots once I have it in front of me - hopefully some time next week and bump the thread

Cheers

Baz

ecc83

"I've seen a few where the power transformer has died as well, even with the correct fuse value in. I wouldn't risk it." Then I bow to your vastly greater experience IC! The only mains traff I had actually fail was in an A30 where the punter kept feeding it fuses all night because the GZ was arcing and blowing them. Eventually the HT winding gave out!

You cannot of course also rely on Joe P to fit the correct fuse rating! (PRESENT company of course excepted!)

Dave.

SunDevil

I had a brief conversation with Mr Alessandro yesterday - seems it's 120v or nuffink'

Amp is now in the UK and I should have it mid-week - more pics to follow when I do

ICBM

The real danger is with amps with a chassis IEC socket. It's very easy to just connect a UK power cable, plug in and turn on. Usually it will just blow the fuse - but not always.

Even I've done it . Amp on bench, US IEC cable connected to stepdown transformer, plugged it into the amp and turned on... or so I thought. Wrong cable! There was a UK one on the bench too, already plugged in at the mains. OK, I was careless and luckily it did just blow the fuse, but I can forgive others for making the same mistake. That's why I'm not a fan of using external stepdown transformers, if it can be avoided.

ecc83

Yes IC, it is easy to do and it was stuff 'kicking around the office' that got plugged in wrongly.

The OP's amp is a combo? Might be room for a dedicated auto- traff in there?

Dave.

SunDevil

Hi Dave

The Alessandro is a head, but I have my own colour coding system - white leads = US and Black UK, plus I have all the US stuff grouped together

So far, so good...!