Older Electra multi's

[epi0205]

I have a couple older Electra 515AC Pedal Power
multi pedals and was curious if I could/should
rewire the power leads for a 3 prong ground? At
present they have an old standard 2 prong source.

Also, What 9V leads am I looking for to use these
with multiple FX stomps? Is there specific pedal
9V leads/cables that I need to look into? Sorry to
be such a goofball, Just don't know much of
anything about this stuff...
Thanks for any help/advice.
Pic of the units;
http://i598.photobucket.com/albums/tt68/tgifntx/Electrapedaldriver2.jpg

[Ch0jin]

It's a little hard to say without inspecting the device, how old is it?

Generally speaking, if the case is plastic, it's likely it was designed to be double insulated making an earth connection unnecessary, but if it's so old the case is metal, then yes I would replace the mains cable with a three core and earth the case.

Regarding the 9V leads, it's a little hard to tell what kind of jacks they are from the picture, but I'm almost certain you'll need to "roll your own" as it were.

Step one would be get that bit on the left apart and see exactly what type of jack it is, I doubt it'd be anything so esoteric you couldn't buy plugs from your local electronics store or online. Failing that, if it's as old as it looks, those jacks won't be PCB mounted meaning it's likely you could swap them out with a different type if you desired. In any case the pedal end (assuming you want to power Boss type pedals or similar) is a 2.1mm DC power plug, also available from an electronics store or online.

Lastly, you're going to need to make sure when making up the new cables you get your polarity right for the pedals your powering. "Standard" (Boss, Ibanez, most boutiques as well) will be center ground. Be wary of old, or hand made fuzz's though that will be looking for 9V on that center pin. You'll waste 'em plugging a center ground supply into one of those.

Oh and I'm not ruling out the option of buying some pre-made cables, it's just that I make my own, so I'm not sure where to look to buy them. (also you'd still need to determine what type of jack is on the box on the right)

Anyway :)

[epi0205]

Ch0jin-
Thanks so much!!! Well... I'm not just real certain to their
age and yes sir, You'd be exactly right in that they are metal cases.
Sorry 'bout that... I should've dropped a little better pics in on this.
Here's a couple that may show it a little better...
http://i598.photobucket.com/albums/tt68/tgifntx/Electra515ACplugs.jpg
http://i598.photobucket.com/albums/tt68/tgifntx/Electra515ACinside.jpg

[Ch0jin]

OK cool, yeah the inside shot helps a bit.

With regard to earthing a new mains lead, I'd use the left hand side bolt holding the power transformer to the case. Remove both bolts and carefully move the transformer and PCB out the way so you can use a file/screwdriver/anything really, to expose some bare metal around the hole on the left hand side. You're trying to ensure you make a good electrical connection for the earth wire. From there you have a few options. The correct way to do it would be to use a solder lug like this (http://jaycar.com.au/productView.asp?ID=HP1350) and a star washer.

You'd solder the earth wire to the lug, then assemble with star washer against the case, then tag, then transformer and tighten. I have seen people just make a loop out of the earth wire and use that instead of a lug, but thats a bit of a hack although, done right, it'll work just the same.

For the DC cables, I was expecting to see a center pole inside the socket (have a look at any of your stomp box's to see what I mean) which would indicated it was a typical 2.1mm (Sorry, I'm Australian, I'm not sure what that is in imperial) socket. In other words, the same socket as your stomp box.

Based on your measurements though, my next best guess is that they are 3.5mm (1/8") mono or stereo audio sockets. Mono would be sensible as you obviously only need 2 connections for DC, but the extra unused tag on the sockets might indicate they used stereo sockets, or they could just be mono sockets with two "hot" tags. It's not that important though.

If I'm right, you should be able to plug in any 3.5mm audio (1/8") plug and it'll fit. First thing that comes to mind are a set of headphones. My first caution though. I wouldn't just plug my headphones in to check the fit without either discharging the filter caps or snipping the red wire. There's a chance that even unplugged, the caps might hold a residual charge, and I'd not like to jam 9VDC into my sensitive headphones. I have dozens of audio connectors lying about so I'd actually just use one of those to test the fit.

So if all that works out, you'll need 4 of these (http://jaycar.com.au/productView.asp?ID=PP0116) (or similar, you can go plastic for 1/4 of the cost, but the metal ones are of course more rugged) and then 4 of these (http://jaycar.com.au/productView.asp?ID=PP0531) (again, plastic versions also fine if you feel metal is overkill for your application)

Lastly you'll need a length of dual core cable of almost any type. For 9VDC you can use ribbon type cable or coaxial type cable with no drama. You're limitation will be the thickness. You'll want something thats going to physically fit inside the plugs. Cramming some thick heavy duty cable in there will not help at all electronically at 9VDC <1A, so go for physical properties rather than electrical. My old pedal setup used 1/8" mic cable and my new one uses 2 core ribbon cable and there's no difference.

So I think that probably covers the "how-to" so it's time to get all serious.

I hold a restricted electrical certification, meaning I'm trained to replace mains cables (amongst other things). To do so without certification in Australia is illegal as there is the obvious risk of electrocution. Now I'm assuming there are similar regulations where you are, but in practice I'm doubting your going to sue yourself if you either injure or kill yourself doing this, and it's a very simple procedure so I'm comfortable advising you on how to do it, but keep in mind that I'm publicly stating that I accept no responsibility for you getting hurt if you mess it up. Check and double check the power side of this project before turning it on.

Sorry to be so blunt, but mix up your power wires doing this, forget to unplug the power lead before de-soldering the cable and you'll get electrocuted.

On a happier note, as you seem to have two of these babies, you could probably even make one of them negative ground (standard) and one positive ground for all your boo-tique fuzz's if you liked. I'd need a better shot of the bottom of the PCB to confirm, but I'd say it'd be dead simple. All depends what your pedal board looks like.

I have 3 positive ground fuzz's, all Germaniums but I run all of them on batteries only so for me, I'd leave both power supplies as negative ground, but it's all up to you :)

[epi0205]

WOW!!!
I can only assume, Somewhere in the phraseology in your certification
it clearly states; Oh and by the way I AM A BADA$$! Incredible Ch0jin!!!

I will get just some of that busy putting together all the pieces called
for and will most certainly get a shot of the pcb prior to doing anything.
Let me first and foremost THANK YOU for your consciencious alerts and
concern for all of the what's/don'ts. I surely appreciate that!

As for my "pedal board"... Well sir... It is still in design stage as I want
to build it myself. The ol' minds eye is seein' a case when a person
opens/removes the lid it is in effect the pedal board..? Nothin' new or
different undoubtedly... Just semi-custom built for what I'm wanting.
In all reality, I would be using the "Barber" disto/gain - the "Morley"
wah - the "MXR" preamp and sustain pedals. Might consider the
"Rocktron" hush in the mix to..? Yes sir, I'm with you on leaving them
both as neg ground. Oh and too, You're on the money in the headphone
jack fitting.

Ch0jin, Thanks again! Top shelf podnah, TOP SHELF!!!
pcb pics;
http://i598.photobucket.com/albums/tt68/tgifntx/515ACpcbbottom.jpg
http://i598.photobucket.com/albums/tt68/tgifntx/515ACpcbtop.jpg

[Ch0jin]

Haha thanks Epi, I've learned a lot hanging out here so it's always great to be able to help out when I can.

Thanks for the PCB shot. Looks like a -real- basic circuit. Half wave rectifier into a 4 pin voltage regulator with that little trim pot being a voltage adjustment. One cap to smooth the input voltage and one to filter the 9V output. The resistor is just a current limiter for the LED.

Just one other note on the replacement power cable, I forgot to mention it because it's pretty basic, but just to be safe, I think I read somewhere ur in the USA, so your new cable will likely have a red wire, a black wire and a green wire. Alternatively it could be brown/blue and green w/yellow stripe (the standard in Europe and Oz). The red and black wires are active and neutral and as they carry your 110VAC, they replace the two black ones there now. In this design it matters not which one goes where. The green one is your ground that you'll connect to the case. Sorry if this is stating the obvious to you, but getting this wrong and connecting the red or black wires to the case is the worst possible thing you can do.....

Do you have access to a multimeter? It's good practice to double check your new power lead before turning it on by making sure you measure Open Circuit from Active to Earth and Neutral to Earth.

Also, given that the 9V line is not fused, (a little mod to consider would be an in-line fuse holder with say a 2A fuse in the 9V line. That'd stop a malfunctioning pedal from wrecking your power supply) double check you new 9V cables to make sure they measure OC from + to - before plugging them in for the first time. It can be fiddly work making the 9V cables and it's not hard to accidentally create a short, especially if you use the metal 2.1mm power plugs. Lastly using a multimeter is going to make it really easy to make sure you get your polarities correct too.

Well I think that about covers it, let us know how you get on :)

[epi0205]

Righteous my man!!!
Yes sir, I do have a multimeter and the inline fuse
is a GREAT piece of advice.:AOK I had to put out
a couple personal fires today... Sooooo, That ate
up most of the day here.:thwap I'm on it tho and
I'll get this going my way just right quick.

I genuinely THANK YOU for all of your help and
FANTASTIC insight on this. You betcha', I'll get
a follow up just as soon as I can.
Thanks so very much sir!!!