Nasty electric shock!

[Guy Pettigrew]

While plugging stuff in and out of my pre 3 the other day I got an enormous belt from the casing.

A check with a meter showed the case was at 350vDC. Ouch!

With 'phone guidance from a very knowledgeable friend we tracked it down to a detached 0v lead from the power supply circuit board to the back of the CliffCon connector.

Just though this was worth mentioning in case anyone else's pre 3 decides to bite them.

Guy

[bob orbell]

Hmm, a Pre III with a Cliffcon conector this must be quite rare. BOB

[pre65]

Originally Posted by bob orbell

Hmm, a Pre III with a Cliffcon conector this must be quite rare. BOB

Might be like calling a Dyson a Hoover ?

[Richard]

Yes Guy may get back to us as I've a vague idea he may have WAD2 set up upgraded to WD3. (WAD2 used Cliffcon connectors for the umbilicals and WD3 used Binder ones for anyone wondering what we're on about.)

Either way we get the gist that Pre case, which is connected to 0V rather than mains earth, went live. I would suggest anyone concerned about this checks the connections inside PSU Pre Phono and the umbilicals themselves as regular plugging and unplugging might cause pins to loosen or soldering to break. These connections reside alongside each other so must be firm and isolated.

Of course it's difficult to foresee all possible problems, and even a mains earth connection could become detached and connect itself to a nearbye live pin.

I wanted all my cases to be mains-earthed though and so used 5 pin Binders which fit in place of the 4 pin ones on WD3.

Simply, the extra pin is used for the cases' separate mains earths back to psu. 0V and all other circuitry is isolated within the case and floated off it with 100R. It might be possible for these umbilical mains earths to become detached but if the cases are configured to be connected to mains earth their earth posts can also be linked externally together and to power amp and TT etc. This would be a safeguard and also gives definite benefits in my system at least in finding the lowest noise earth connections.

For anyone considering a new build or modding theirs, I used Pin 3 throughout for mains earth so it could not be made incorrectly when a builder (me!) is trying to interpret the pin numbers from either side of the connector - at least mains earth would be correct. The other pins were kept the same order as original build.

There is a very good 5 core cable available from Farnell.

Details of build are here,

http://www.world-designs.co.uk/forum...t=binder+earth

Part numbers of plugs, sockets and cable here,

http://www.world-designs.co.uk/forum...t=binder+earth

[Guy Pettigrew]

As Richard says, I used to have a PSU II/Pre II combo which I upgraded to the III. What an incredible memory you have Richard!

So, no I wasn't in error when I said it has a Cliffcon connector.

In fact, I started with the venerable KLP1 line stage pre. The Pre III is built into the original KLP 1 casing because I like the look of it and the fascia gives me enough room to run separate volume controls for each channel. Effectively a balance control without using any extra components.

Sorry about the small picture, bit of a numpty at this sort of thing!



Guy