Help me add a switch !

hey, Im using a 3amp toggle switch and I would say anythg around there should be ok.

Also rockers needs bigger holes than toggles and it might be hard to drill or cut on the back panel.

Hmm...

Well, first of all, that whole IEC socket should be covered for safety (the metal running flat from the live pin to the fuse will is live).

And the ground pin (top centre) should be connected to the metal chassis for safety.

Adding a switch should be easy, but be VERY careful when working with mains voltages.

Always double and triple check your work before plugging anything into the wall.

A simple rocker switch will do fine. You should choose a SPST (Single Post, Single Throw; it will have two tabs on the back), or a SPDT (Single Post, Double Throw; it will have three tabs on the back) if you can't get a SPST. When looking for a switch, just make sure it's rated for mains voltages, the amperage will be fine, the CKKIII won't be drawing anywhere near a whole amp.

It should be placed on the live AC line (the brown/black wires in the photo), between the IEC socket and the CKKIII.

A wire should be soldered from the IEC socket where the black/brown wires are currently to the outer-most tab of the switch, then the brown/black wires to the inner-most tab of the switch.

The tabs you use on the switch are important with a SPDT switch because when the switch is in its 'off' position, the centre tab is actually connected to the opposite outer tab. If the IEC socket is connected to the centre tab then the free tab in the switch will actually be live; with the IEC socket connected to an outer tab, this is not the case.

All connections must be insulated with heatshrink, make sure there's nothing touchable that may have mains voltage in it.

Hope that all makes sense.

Yes, in terms of installation, toggles will be easier because they generally only need a 6mm hole drilled, whereas rockers can need 12mm.
 

Quote:

Originally Posted by tamu 

hey, Im using a 3amp toggle switch and I would say anythg around there should be ok.

Also rockers needs bigger holes than toggles and it might be hard to drill or cut on the back panel.

You'll want to install the switch in series with the purple and black wires coming out of the lower (the one after the fuse) tab.  This means the wiring scheme will be: tab after fuse (what the black and purple wires are currently connected to) -> some wire -> switch -> black and purple wires.  This way if the switch is off you don't have continuity, and if it's on you do therefore being a power switch.  Keep in mind the purple and black wire are acting as effectively one single wire.  Anything you do to one, you need to do to the other.

Hope this helps.

Edit: Elliot explained the same thing better than me already...

you dont have to ground and the wiring looks correct.

if your gonna ground the amp make sure you check the amb instructions. there was somethg about it

Edit: if your not gonna open the casis again then leave the covering part alone too.. if you want to go on anyway, then you can buy covers for the iec input.

and it has to go to trafo/toroidal not pcb

Yep but again its gonna be a mission to put the switch on.. it might be much easier if its plastic or wood panels that your gonna be putting it on but if its AL then its hard to cut the correct hole for it.

glad I could help. enjoy diy-ing your amp

Quote:

Originally Posted by tamu 

you dont have to ground and the wiring looks correct.

 

if your gonna ground the amp make sure you check the amb instructions. there was somethg about it

 

Edit: if your not gonna open the casis again then leave the covering part alone too.. if you want to go on anyway, then you can buy covers for the iec input.

 

and it has to go to trafo/toroidal not pcb

The IEC ground should be connected to the chassis since it is metal. It's a safety feature in case anything inside shorts at any time in the future for whatever reason. The diagram on the "Wiring & ground" page at http://www.amb.org/audio/ck2/ shows the IEC ground connected to the chassis, as well as the PCB ground.

Also, covering the live contacts is a good idea, regardless if you think you'll be opening up the chassis in the future or not. It might be sold to someone who does open it up and isn't so cautious.

As tamu said, you can get PVC sheaths for IEC sockets. Or you could cover it well with electrical tape which I have done in some cases (flat over the exposed metal, then around the IEC to hold that flat bit in place).

I'd always err on the side of caution, especially when it comes to mains power. One slip up is all it takes to do some serious damage.

That switch is fine, but it's going to be a pain to cut a square hole in that metal chassis. A small round toggle switch would be easier.

Diagram looks good 

Quote:

Originally Posted by tamu 

you dont have to ground

Yeah, you do, if you want to live a long and healthy life. Sure, something bad probably won't happen, but if it does, you could instantly be exposed to wall voltage. It's also a legal requirement in most places (that exposed metal be grounded) - whether or not the law applies to DIY products isn't terribly clear, but it's a good idea to follow it to keep yourself safe. You can always use a ground loop breaker if you're worried about introducing noise.

As far as covering the live exposed parts of the IEC socket - again, it may not be completely necessary, but considering it only takes a couple minutes and could potentially save someone's life, why wouldn't you?

Don't run around telling people it's ok to ignore safety protocol when working with potentially lethal voltages.

Quote:

Originally Posted by Dojomoto 

 I know the star ground on the PCB has a bolt going to the chasis already, and I have never encountered a shock by touching the chasis, so I figured although it seemed strange no ground wire was on the IEC that it was safely grounded another method.

If nothing is connected to the main IEC ground, it's not technically safe. Connecting the internal (signal/PSU) ground to the chassis is not the same as earth ground, if the chassis is not connected to earth ground. You wouldn't get a shock unless anything failed, and if you did get shocked you may not be alive to worry about it. As it stands (by what you've described), if somehow the hot wire were to come in contact with the chassis, it would energize the chassis and would not have a direct connection to earth ground. There would be a good resistance between the supply voltage and the supply ground, allowing the chassis to maintain a potentially lethal voltage because there may not be enough amperage to blow the fuse. If the chassis had been connected to earth ground, the hot wire would have a direct (low-resistance) return path, causing a high amperage current which would blow the amp's fuse or your home's circuit breaker, ensuring that the chassis did not remain energized for long.

I don't mean to be all doomsday and preachy about this, but when you're dealing with something potentially lethal, it's best to take every feasible safety precaution.

Ground loop isn't usually a huge problem (and easily taken care of with a few components if needed). I'm in the process of building a gainclone right now so I've been doing a lot of research into the power supply, grounding, safety, etc - hence where all this came from.

I don't mean to belittle the work of the builder (it does look well built), but if you're already in there it makes sense to do everything you can. Good luck!