[fajimr]

hi all

After sitting in its box for the last 4 months, my AKSA 55N+ has finally been freed by this DIY numpty... after reading and re-re-re-reading the construction manual, I've felt pretty good about installing the resistors, capacitors and am now getting to the good stuff...  

so I am reading ahead (again...), thinking about the testing phase and I start to get all nervous ... Assembling the power supply unit seems straightforward... got the Piltron transfos.. a DIMM (which I played with checking out resistor values- it took me a while to realize I couldn't measure them sitting on the table... I even spent some time on the internet wondering how to test my DIMM to make sure it was working correctly  a chassis even... but now I have very little idea about how to:

1)  wire up the transfo to the power supply (yeah I know there are some directions and a schematic and I can probably figure out that part.. no photos though!!!!).  

2) wire up the transfo to an electrical outlet.  again there is some description but no photos!!  

3) deal with things like discharging the capacitors with a light bulb... I can't even imagine how I would tackle this although I imagine that many on this list would love to see me try

Bill Eckle's website is helpful http://www.wmeckle.com/AKSA/Case.htm

but I was wondering if anyone out there has some photos of this part of the construction/testing...  I've spent a few hours searching old threads and couldn't find anything.

or maybe I'm just being a bit premature about all this and once everything is assembled and ready to go it will become apparent.  

as always, I'd appreciate any comments or insights you have... It's been a great experience so far

[AKSA]

Hi Jim,

Try this one:

IDENTIFYING POWER TRANSFORMER WIRES

It is possible that there is no documentation for the transformers you have acquired for your AKSA 55W amplifier, and as a result the wire coding is unknown.  The following procedure should solve the problem.  Please proceed as follows.

When measuring AC, use the AC mode on the DMM, and when measuring DC, use the DC mode.  Do not mix the two; measuring AC on a DC mode and vice versa will give strange readings.

You need to make three terminations of four secondary wires.   One single wire is AC1 input on the power supply PCB, while the other single wire is AC2 input.  These go to the two spade connectors on the AC input of one side of the rectifier board. The other two wires, the third termination, are connected together and hooked to Star Earth.

1.  Identify the two windings. Each has two wires, a start and a finish.
2.  Connect the primary of transformer with insulated wire to a mains outlet. Take great care to do this properly, as some transformer have dual windings on the primaries for universal use. Generally the color coding is blue and brown (active), but codes do vary around the world.
3.  Make sure all secondary outputs are accessible with the DMM probe.
4.  Find one secondary winding, and measure on AC mode from start to finish. Should be around 25Vac, plus or minus for or five volts, depending on your local grid voltage. It varies according to area and time of day.
Make the measurements for the other winding; they should be identical, with up to one volt difference.
5.  Now, connect one wire of each of the two windings together. Put one probe of the DMM on this joined wire, which will be Star Earth.
6.  Now, measure from the two conjoined wires to the other two wires, let's call them AC1 and AC2. Each should measure 25Vac as before with respect to the two joined wires.
7.  Measure from AC1 to AC2. If you have the wiring correct, this voltage should be 50Vac, plus or minus around 5 volts AC. If it is only 1 or 2 volts, then you have the wiring wrong, so swap ONE of the conjoined wires for the other wire of the SAME winding, then measure again. This time you should have the 50Vac required.
8.  Once you have identified the correct wiring regime, hook the two conjoined wires to star earth permanently, and AC1 and AC2 to the two AC tabs on the power supply.  Be sure to connect to ONE of the TWO power supplies on the pcwer supply PCB, viz. don't interlink between power supplies from the same transformer. One transformer links to one power supply, say PS #1, and the other power supply/transformer becomes PS #2.


The trafo manufacturer should have made it clear which are primary and which are secondary leads, but unfortunately most use differing color codes on the secondaries.  The technique above will work fine, and to connect the trafo to the mains is no problem once you know the primary leads, which you can 'hot' wire if you use insulation tape for testing.

Cheers,

Hugh

[PSP]

Hi Jim,
I have built three 55's, all of them using Plitron transformers.

Tonight I will look at the color scheme Plitron uses and take some pictures that I can send you.  When you look at the pictures and compare them to Plitron's schematic, all will be clear.  If not, all you have to do is ask.  

I don't have a website set up, and I like to take high resolution pictures so you can study them for detail.  The AC gallery specifies low resolution pictures, so I'll have to e-mail them to you.  PM me with your e-mail address.

Have you decided on a chassis, power switch, etc?

Peter

[fajimr]

thanks Hugh... I did happen to read this a few times in the instructions...  
It's just things like

 "2. Connect the primary of transformer with insulated wire to a mains outlet."

how do I do something like this? Do I wire it up to my IEC power inlet?  If so which connection do I attache the wire to?  Like I said, quoting someone else here, I am a true DIY Numpty.  If anyone knows of a place to learn about this, let me know and I would be happy to go there.  I do have a couple of books on electrical circuits and testing with a DIMM but nothing which shows you how to do this wiring thing.    

Remember you are talking to someone here who, when assembling the PCBs, sorted all the resistors using an Dimm, then read each step, checked the photo with a magnifying glass, went back and read the step, looked at the PCB, rechecked the resistor values with a DIMM, soldered, checked each solder with a magnifying glass.....  Now when you add electricity to the formula, I become more careful  

hopefully I'll make it out the other side without too much head damage     I am having fun... really

Peter- thanks, I've PM'd you.

[AKSA]

OK Jim,

My apologies, didn't realise.......

Locate the primary of the transformer;  there will be two wires, one usually blue (neutral) and the other usually brown (active).

On the power cord, there will be three wires, blue, brown and green.  Green is earth, and can be connected to chassis, or, if you are just testing trafos in isolation, leave unconnected.

The other wires, blue and brown, can be connected to the primary of the trafo.  You can simply wind these wires together with your fingers, but they MUST be insulated with proper tape to keep safe once connected (and plugged in!).

Now, after checking all the secondary wires are accessible and not connected to each other, plug in the power cord and switch on.

At this point you can test with your DMM on AC 1000Vac according the instructions given in my earlier post.

This will enable you to identify the various wires on the secondaries.

Don't hesitate to ask if you have difficulties, Jim.  This stuff is safety related, and a mistake might take out the house wiring - or worse......

Cheers,

Hugh

[fajimr]

thanks Hugh.. this is exactly the stuff I need.  And it is starting to make some sense to me...  but I really don't trust myself at this point

as I hold my trafo in my hand there are 8 wires: a set of black/brown (set meaning they come out of the trafo together with a black sheath), another set of white/orange, then 4 individual wires: red, yellow, blue, grey.

The on the side it says:
INPUT: 2X 115 VAC  BLK/WHT     BRN/ORN
Output: 2 X 25 VAC  RED/YEL      BLU/GRY

the schematics don't make much sense except that is looks like if I wire it one way I get 115 (BLK + BRN/ WHT + ORN?) and the other way 230 (WHT + BRN?).  Of course the options for Type A primary, single secondary, and dual secondaries are beyond me.  here is a link to the Plitron schematic from the website  (www.plitron.com).



At least at this point I think I can start testing... but first I need to finish my PCB and power supply boards...

[AKSA]

Jim,

That's it!  The primary connection for 115Vac mains is the left one;  black to brown for active, and orange to white for neutral.

When you are ready to connect the secondaries, let me know and I will assist!

Cheers,

Hugh

[PSP]

Jim,
As Hugh has said, the diagram you have posted is correct for the primaries:  

combine black and brown--> neutral
combine white and orange--> hot[/list:u]For the secondaries, you want another portion of the Plitron diagram that does not appear in the small section that you posted above.  The correct choice is in the "Dual Secondaries" part of the diagram, specifically the "Center Tap" diagram.  That specifies:
Red-->AKSA power supply pcb AC spade
Gray-->AKSA power supply pcb AC spade
Combine Yellow and Blue-->AKSA power supply pcb Single Point Ground.[/list:u]I have built four AKSA amps using Plitron xfmrs, and this has never caused any smoke in the basement!

Good luck,
Peter

[fajimr]

thanks Peter and double thanks for the e-mail and detailed photos.. am I the only one who has ever asked about this??

next comes the power supply and then testing... I am feeling better though

and just in case anyone is wondering... here is the schematic for the secondaries:  

Jim,

The correct wiring schema is CENTER TAP;  with the center tap becoming STAR EARTH.    Cheers, Hugh