Line 6 AX2 Power Transformer Hookup

[Lordbovary]

I recently received a dismantled Line 6 AX2 amp. I was able to get everything back together, but I am in desperate need of how to hook the circuit boards to the power transformer. There are something like 6 colored wires. I need to know where they hook onto the transformer. Help me Music Electronics Forum, you're my only hope.

[Enzo]

I'd have to guess there are high voltage winding with center tap for the power amps, and probaly a low voltage winding with cente tap for the preamp.

Are the primary wires still connected?

I'd power up the transformer and chart what wires make what voltage. I guess I'd use an ohm meter first to group the windings.

Once you know what is what there, look at the circuit board. it should be easy to spot the main rectifiers. The high voltage wires would go to the heftier rectifiers or bridge, and ultimately to the larger filter caps. Then the low voltage wires to the smaller rectifiers. The center taps would be grounded.

If you have something other than two center tapped windings, tell us what voltages there are.

[Lordbovary]

Thanks for the help so far. I have isolated the high voltage versus the low voltage side of the transformer, and which leads on the transformer are connected. Now I just need to trace the wires on the circuit boards. There are two boards. One with the A/C input and two wires and the other board containing five wires with the large capacitors and the other components. I assume the side of the transformer with the low resistance hooks to the high voltage A/C board, and the high resistance side of the transformer suppling the other board with the lower voltage. Once again, thanks again for the help and quick response, Enzo. I am in my first year of an Electronics Technology program and I thought this would be an excellent learning experience, but I am kinda flying blind.

[Enzo]

Why not show it to your instructor? This is an excellent example of a real world situation. When I train people I ALWAYS try to provide real world examples of the things we cover.

Are your saying there are six wires TOTAL coming from the transformer? or are there six wires for the circuitry PLUS the mains wires? That was the first post. Now you mention 2 wires and five wires. We really need to describe precisely what we have here or we don;t communicate.

I try to use the European term for the AC power from the wall, "mains." I grew up calling it the "AC Line," but that can confuse people when we also talk about line inputs, and in signals.

In any case, when i talked about high and low voltage, I was not referring to the mains or AC powerline. I was referring to more than one secondary voltage windings. one would be of higher voltage than the other. Neither would be up to 120v level though. So I don;t think in terms of high and low sides of a transformer. I think in temrs of primary and secondary sides. primary being the input side - connected to the mains, and secondary being the side connected to your circuitry.

Resistance of the winding is not a good indicator.A low voltage high current winding will usually have lower resistance than the 120v winding.

How many groups of wires are there? In other words, the primary wires would be one group. They would have continuity between them of some resistance. They would not have continuity at all to the other windings. SO some wires will show resistance to others, meaning they are part of a particular winding, but wires that show open to the other wires are not part of their winding. That will tell us how many windings you have.

[Lordbovary]

I believe there are seven windings altogether. On one side of the transformer there are 3, that is three different terminals, out of six, that all have continuity with each other, and when I apply power to the transformer, it seems one winding is about 27V, the second is 134V, and the last is 161V. That side of the transformer sits next to the main circuit board, where the A/C (main) comes from the wall. There are two wires coming from the main board colored white and brown.

On the other side of the transformer there are 4 windings. Two terminals make continuity with each other and they are at about 12V. Lastly there are 3 other terminals that make continuity with each other. Across the two on the outside, there is about 73V, and then each outside terminal paired with the middle terminal is about 38V a piece. That side of the transformer sits next to the circuit board with the large capacitors and rectifiers. There are five wires out of that circuit board colored orange, yellow, green, blue, and red.
So there are seven wires to hook to the transformer, and seven windings on the transformer.
Am I to believe the two wires on the main side can be hooked to the transformer to produce different a different total voltage, either 134V or 162V?
Once again, thanks.

[Enzo]

OK, terminology here. Winding and wire mean two different things.

A winding means a piece of wire wrapped around the transformer core a number of times. Two separate pieces of wire, not connected together, wrapped (or "wound") around the same transformer core would be two windings. Since every piece of wire has two ends, and winding on a transformer must then result in at least two wires coming out - the two ends of the winding wire. A winding could have "taps" or connections in mid-winding, and each tap would have its own wire coming out.

A transformer can be made with the winding-wire ends spliced to regular insulated wire, so vasrious color wires are stickijng out. or the ends of the winding-wires (which are enameled solid copper) can be brought out to a row of solder terminals.

Now then, your 12v and 73v do sound like the transformer secondaries. The center wire of the three is your center tap, and it will go to a ground connection. That leaves a pair of 38VAC wires for the power supply for the powr amp.

it sounds like you have the transformer with solder terminals, and your wires are connected already to the circuit boards. I have no idea which color wire goes where. You would have to look at the copper traces on the circuit board trailing off from where each colored wire is soldered on, and determine what it connects to.

The two 38v terminals would go to the large rectifiers that feed the largest filter caps. the two 12v connections would probably go to either a smaller set of rectifiers, or if there is a vacuum tube, conceivably direct to pins 4 and 5 of its socket.

Now so far, my suggestions are based on what I THINK you have, no guarantees.

The mains side will have more than one connection so it can be wired up for various power line voltages around the world.


And another terminology point. A wire or a point in a circuit or a terminal on a transformer - a single point does not have a voltage all its own, it only have a voltage with respect to something else. COnsider a 9v battery. You cannot say there is 9 volts on one of its terminals. You can only say there are 9 volts on a terminal with respect to the other terminal. SO a terminal on a transformer cannot have 134v on it, it can only have 134v compared to some other terminal. In other words, both ends of your meter connected to something, not just one.

When you apply 120VAC from the wall, we need to know what you connected it to, then we also need to know where you connected your meter to get the other readings