[CButterworth]

I have been building the AKSA 55 which I recieved in the mail from Hugh earlier this week. The instructions are excellent.  However, I have a couple of questions regarding the power supply toroids.

1a.  I have two toroids from Avel Lindberg - Y236504.  Each toroid has two primary windings.  Should I use both of the primary windings?

1b.  For the primary windings, there are four wires - blue, grey, violet and brown.  On the toroid, there are two small dashes next to the blue and the violet.  I would have taken these to represent negative rather than positive wires, although the power input will be AC.  OK, so if I use both primary windings, then should I connect the Brown and Grey to the "active" or "positive" side?  Is there a standard for IEC plugs?

2. On the secondary windings, there are four wires - Black, Red, Orange and Yellow.  The black and Orange wires have "0V" next to them, while the Red and Yellow say "25V/3.2A" next to them.  STUPID QUESTION - the Red and yellow go to the AC in on one module of the power supply don't they with the Black and Orange going to Star Earth?

3. Hugh's diagram shows a 220nF cap and a 100R 1W resistor going between the Active and Negative wires - this is obviously some kind of filter.  So, can the "Active" wires from each toroid (four in total) be wired with one arm of the Capacitor directly to the "Active side of the switch?  Can the Negative wires of the toroids be connected directly to one wire of the resistor and soldered to the Negative side of the switch?  The, I'd just join the free arm of the Cap with the free arm of the resistor?

I'll welcome and wait for any comments.  I am waiting for my chassis from Par-metal to arrive and want to mount all components (except for the gluing the power supply) into the chassis, prior to connecting the amp to electricity.

Thanks,
Charlie Butterworth

[AKSA]

Hi Charlie,

Thank you for your email.

1a.  I have two toroids from Avel Lindberg - Y236504.  Each toroid has two primary windings.  Should I use both of the primary windings?

Yes, absolutely.  They must be wired in parallel for 120Vac mains.  You need the Y23 series connection information available either on the documentation with the trafos or on their website here:
http://avellindberg.com/transformers/y23_range_connections.htm

1b. For the primary windings, there are four wires - blue, grey, violet and brown. On the toroid, there are two small dashes next to the blue and the violet. I would have taken these to represent negative rather than positive wires, although the power input will be AC. OK, so if I use both primary windings, then should I connect the Brown and Grey to the "active" or "positive" side? Is there a standard for IEC plugs?

Strictly, brown is ACTIVE while GREY is NEUTRAL.  However, a toroidal is essentially undiscriminating on polarity;  it matters not which is which, though there is an argument that the switch should be connected only on the ACTIVE wire.

STUPID QUESTION - the Red and yellow go to the AC in on one module of the power supply don't they with the Black and Orange going to Star Earth?

I'd best not answer this here because you need to satisfy yourself you are complying with the wiring diagram supplied by Avel Lindberg.  However, if there is any doubt, you'll find a section in the instructions in 'Identifying the Transformer Connections' on Page 35.  The technique given is long-winded, but failsafe. [/quote]

3. Hugh's diagram shows a 220nF cap and a 100R 1W resistor going between the Active and Negative wires - this is obviously some kind of filter. So, can the "Active" wires from each toroid (four in total) be wired with one arm of the Capacitor directly to the "Active side of the switch? Can the Negative wires of the toroids be connected directly to one wire of the resistor and soldered to the Negative side of the switch? The, I'd just join the free arm of the Cap with the free arm of the resistor?

This is a snubber, whose purpose is to lengthen the life of the mains switch by damping any arc produced by inductive kickback from the trafos at switch-off.  It's not essential, of course.

It appears between the switch and the transformers, between active wire (on the switched side is fine) to the neutral (NOT negative!) wire.

Be very careful you do not wire the switch ACROSS the active and neutral.  On first throwing the switch, you would have a direct short which would take out the entire house electrical system!!  I may well be misinterpreting things here, but words are not adequate.  Follow the circuit diagram.  The cap is in series with the resistor;  the top of the cap thus goes to the ACTIVE and the bottom of the resistor goes to the NEUTRAL.  These wires then continue on to the conjoined toroids.

Charlie, I hope this is clear enough;  email me privately if not.  This is IMPORTANT and you must not get it wrong.  I'm used to working with 240Vac where mistakes are draconian;  120Vac is much more forgiving.

Cheers,

Hugh