Modernising a vintage amp mains input

Guitarse

Not long ago I posted a thread about changing the input socket on my vintage Marshall, from the old fashioned round bulgin to a new IEC 'kettle' type. I ordered the new socket from the Tube Amp Dr, and it arrived yesterday. SO here goes:

I am pretty sure about which wires go where, but something inside me is sh*t scared of getting the wiring the wrong way round and damaging my beloved amp. Here's a few pics to try and explain myself:

This is the bulgin as it is at the moment, all working fine. So, it appears then, that the yellow wire is the Live, the lower black wire is the earth and, obviously the other black wire, to the left, in the middle, is neutral.....Hmmmmm...is it?

http://i1105.photobucket.com/albums/h344/alwoodcock/Mainsinputasitis_zps87801c82.jpg


These are the wires going to their components (yellow to one of the fuses, black to earth on the chassis)

http://i1105.photobucket.com/albums/h344/alwoodcock/Inputsocketwithfuseandearthconnected_zpsccc94857.jpg

Here's the new socket, laid alongside the old:

http://i1105.photobucket.com/albums/h344/alwoodcock/Inputwithnewascomparison_zps2d52d60a.jpg

So, am I correct about the Live Neutral and Earth wires? Once I'm confident, I can go ahead!


Thanks

Al

ICBM

Yes, that's correct. For the avoidance of doubt the earth wire is the one that goes to the chassis connection of the filter cap can directly below the socket.

I assume you know that you will have to file out the chassis to get it to fit. The screw holes match though, and it does completely cover the old hole, unlike the standard 'horizontal' IEC sockets.

Guitarse

Great! Thanks ICBM....Now, where did I put the soldering iron?

I'd rather file the plastic on the new socket to be honest (if that's practical?), but I'll deal with that when I get to it in a bit!

ICBM

Guitarse said:

I'd rather file the plastic on the new socket to be honest (if that's practical?)

No, absolutely not! Even if you could get away with it without the socket falling apart it would not be safe. (I doubt it anyway, there's quite a big difference in size.)

You *must not* modify mains sockets or other safety-critical components, period.

Guitarse

Okeydoke!

ecc83

Bit of a shame you do not seem to have a boot for that socket?

At least run some heatshrink up the wires. 

In general it does not matter which wire is live as far as the transformer is concerned but if  the wires are of standard colours, brown live, blue neutral, then these should be wired correctly. If in doubt, the fuse must be in the live side as must the mains switch if it is single pole.

N.B.If you ever intend to sell the modded amp you must get it PAT certified, be a good idea anyway.

Dave.

ICBM

The usual connection on these old Marshalls with only single-pole mains switches is that the live goes to the fuse holder and then the switch, and the neutral goes to the voltage selector.

In fact, while you're at it, it's best to hardwire the selector by moving the wire from the centre connection to the 240V connection. That not only makes the amp more reliable since the selector can't fall out and stop it working, but also stops someone accidentally setting the wrong voltage and frying it.

Oh and while you're at it as well, check the fuse values are correct. And that there's no tin foil/cigarette packet/guitar string ends down the fuse holders...!

Guitarse

I've already put small washers over the screws on the selectors to secure them, and the fuses and values are correct! I do believe there was a piece of tin foil shoved in one of the fuse holders though, many years ago, when I first got the amp! 

Guitarse

Job done! Nice and tidy.....was long overdue! Thanks again ICBM!!