Power supply wiring for Triad transformers

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Power supply wiring for Triad transformers

 

I have the Triad F-31X and F-40X transformers as well as a 110V Eurocord style power receptical with on-off switch and a fuse.  It has three wires coming from it, red and blue which are the Live and Neutral (not sure which is which) and yellow which is Ground.

 

Does anyone have a good diagram and/or a picture of how all this wires together?  Most of what I find online is for the Stancor transformers (which have different color wires) and/or is for a 2 wire power cord.

 

The F-31X has two black wires on one side and three wires on the other side, two red and one red w/ yellow stripe.  I'm assuming the F-31X 10VAC output is equivalent to the Stancor P-8380 in Apple's diagram.  And that the Triad red wires are same as Stancor brown wires. and Triad red w/ yellow is same as Stancor yellow.

 

The F-40X has two black wires on one side and three wires on the other side, two green and one green w/ yellow stripe.  I'm assuming the F-40X 26.8V output is equivalent to the Stancor P-8667.   And that the Triad green wires are same as Stancor green wires. and Triad green w/ yellow is same as Stancor yellow.

 

The motherboard connector has 6 pins.

 

Looking at the Stancord diagrams, I am assuming that the black wires on the transformers go to the Line and Neutral from the power receptical and that the outputs are the colored wires.

 

The F-31X red outputs go to motherboard connector pins 1 & 2 and the red w/ yellow is not used.

The F-40X green outputs go to motherboard connector pins 3 & 4 and the green w/yellow goes to pin 5.

 

The black (ground) wire from the power receptical goes to pin 6 on the motherboard connector.  And pin 5 & 6 on the motherboard connector are also tied together?

 

It's the grounding part I'm not really sure about.  Apple's diagram looks like ti was designed for a 2 wire power cord and I'd prefer, even if it isn't as period correct, to use a 3 prong cord.

 

 

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Measurement

You might want to change the colors on the receptacle just to avoid future confusion. NEMA standard colors are Black for live, White for neutral, and Green  for ground, although the IEC standard of Brown for live, Blue for neutral, and Green-Yellow striped for ground is also commonly seen and easily interpreted. There are mnemonics for remembering these colors, but as they're not necessarily "P.C." these days, I leave it up to you.

If you can't find the primary and secondaries on a mains power transformer, just use your multimeter to check resistance between pairs of wires. The primary and secondary will have infinite resistance between them, and reading between both primary wires will have a higher resistance than between both secondary wires (as the transformer is being used to step down voltage, the primary has more turns). When reading a center-tapped (C.T.) secondary, the center tap is at the center point of a resistor divider with equal resistance legs.

The general scheme for power input wiring is that the live wire from the receptacle goes to a fuse, then the main switch, then an insulated multiple to connect to the primary side of the power supplies. In your case with all linear supplies, that is the primary of each of the transformers. The neutral wire from the receptacle is not normally fused or switched, which is why many appliances carry warnings not to defeat the polarization of the line cord. It goes from the receptacle directly to an insulated multiple, and then again to the other side of both transformers' primaries. The ground wire from the receptacle is connected first to the chassis, and then to any metal panels or shields which must be earthed. A wooden box computer doesn't provide any metal chassis to connect to, but you could wire it to the steel lugs of the transformers and the shield of the cassette in/out ports.

An insulated multiple is a device for connecting multiple wires together while avoiding shorts to other circuits. The simplest is just a wirenut or Wago connector, and there are many other forms such as the terminal strips sold by Phoenix Contact.

When working on primary side voltages, don't assume, measure. Then check your instruments and measure again.

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The datasheets for the Triad transformers ...

... are preferred over measurements. The measurement techniques outlined in the previous post #2 are useful for unknown transformers, though.

 

The datasheets of these Triad transformers can be downloaded from the distributors (Mouser or Digikey being the most likely) --- for most of the components they sell, there is a little botton "Datasheet" on the page for the component. Just klick on it and get the datasheet !

 

About the jack for the line cable - I have noticed that US cables and EU cables may have swapped "hot" and "neutral" wires, at least for the cables I have cut open. It did not dig further into that, it could have been a manufacturing fault ("Made in China", of course).

 

So what I would recommend to you is to plug in your US cable into that jack and find out, by ohmmeter (not connected to the line voltage !!!) where the "hot" wire goes. And then, if possible, swap the colors of the wires from the jack accordingly, to meet US standards.

 

- Uncle Bernie

 

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I think I got the colors for

I think I got the colors for the two Triad transformers wrong above...

 

F-31X is green - green/yellow - green on the outputs

F-40X is red - red/yellow - red

 

 

 

 

 

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Triad wiring

Hi,

Take a look at post 26 of the 'Jumping In' thread where I posted photos of the correct wiring of the Triad transformers. Unfortunately the primary wiring there is just a jumble of black wires, but the secondary wiring is pretty clear. Not clear in the photo, but the center tap of the green transformer (striped green wire) is not to be connected to anything. It is insulated with a bit of heat shrink tubing.

Regards,

Jeff M.

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jmmh wrote:Hi,Take a look at
jmmh wrote:

Hi,

Take a look at post 26 of the 'Jumping In' thread where I posted photos of the correct wiring of the Triad transformers. Unfortunately the primary wiring there is just a jumble of black wires, but the secondary wiring is pretty clear. Not clear in the photo, but the center tap of the green transformer (striped green wire) is not to be connected to anything. It is insulated with a bit

 

Thanks, I will go look for that again.

 

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Where are you and what mains

Where are you and what mains supply are you using ?

 

The apple manual shows a circuit with a single pole switch on one side of the mains supply and a fuse in the other. Now, depending on your mains supply, that may mean you still have a live circuit inside your A1 even with the switch off which just might hurt if you think you have sucessfully turned it off.

 

I use a double pole switch to isolate both mains feeds as I am using a 110V centre tapped transformer to supply my machine which means each supply cable is 55V AC above or below the 'earth'. If I had used 240V transformers, I could have used a single pole in the UK as the neutral is more often than not, at earth potential (provided we don't have a phase imbalance big enough to drive the neutral significantly above ground, but thats a whole different story :) )

 

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I am using a double pole

I'm in Texas with 115V power, and I am using a double pole switch, even though it is probably not "period correct".

 

 

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