Replacing damaged Centertap

[Scaprara]

All-
Need some help. I picked up an powered Subwoofer used. Upon getting home I couldn't get any power. I open it up to find that's the center tap output is cut at a point where I can't even repair. Anyone know what kind of specs to look for? I'm confused by the 3 wire output.

I've looked for 22v center taps with 1.5a output but struggling to find 3 wire output.

 

[Diver300]

You can use a transformer with two 12 V outputs which you would wire in series.

As you are in the USA, I am assuming you only need the 120 V input, and this transformer could be used:-
https://www.mouser.co.uk/ProductDetail/Hammond-Manufacturing/166L22?qs=KLj0QfLrw0GT7dgUl6CqVQ==

That is a slightly higher current rating than the original, so I might be a bit larger. You may find that all off the shelf transformers are slightly larger or slightly less power than the one you have. It is rated at 33 VA, which isn't common. 22 V isn't common either. You may have to change the transformer mounting position if the replacement is a bit larger.

 

[rjenkinsgb]

The transformer label says "22Vx2" 1.5A

A 24V dual winding type may be more appropriate, 60 - 80VA rating?

 

[Nigel Goodwin]

All-
Need some help. I picked up an powered Subwoofer used. Upon getting home I couldn't get any power. I open it up to find that's the center tap output is cut at a point where I can't even repair. Anyone know what kind of specs to look for? I'm confused by the 3 wire output.

I've looked for 22v center taps with 1.5a output but struggling to find 3 wire output.

Are you sure the transformer is 'faulty'? - obviously that can't be a 'fault', and if that's the problem, then it's deliberate sabotage.

More likely the transformer is been used as a single 44V winding, and the unused centre tap was cut off during production.

I presume you aware that many sub-woofers only turn ON when they receive a signal?, you often can't just plug them in and they work, they need a signal as well.

I'd certainly fault find before blindly replacing the transformer, which may not be faulty at all.

If the wire is cut off, is the wire still there?, if it was sabotaged then presumably the wire would still be in place, if it was removed during production, then the wire would never have been there.

Perhaps you could post a wider picture?, showing the transformer and board etc, and preferably not so blurred.

 

[Tony Stewart]

I can only see one of the three secondary wires in this

 

[rjenkinsgb]

It looks rather like the secondary wires have been cut flush with the coil former?
(Underside in the original photo).

 

[Scaprara]

rjenkinsgb you are correct. This is the issue. I have no access to these wires :-(
Nigel Goodwin I did test with everything connected and sending signal. My other sub works fine, this one is dead in the water as I can connect the output to the board.
Diver300 Thanks for the link. I don't know that I'll be able to leverage that one. The connector to the board made use of all 3 wires off the centertap(Red-Black-Red). Assuming I would need similar output from next transformer. Again, novice here, but assuming that black would be ground, and each red is a + 22V output?

 

[rjenkinsgb]

Dual wound 24V transformers are readily available.

They have two separate 0V--24V windings.

Just connect (usually) the middle two secondary terminals together, so 24V from one to 0V of the other, and that common point becomes the 0V "centre tap" of a 24-0-24 transformer, in effect.
The outputs are the first 0, and the last 24V pins.

Example:

 

[Scaprara]

rjenkinsgb Thanks so much! I'll see what I can find! I really appreciate the assist. Will post follow-up once completed

 

[Diver300]

https://www.farnell.com/datasheets/3160290.pdf

That is an example of a toroidal transformer where the connections are wires. One secondary has wires that are red and black, the other has wires that are grey and orange. It says that for a series connection you should joint black with grey. That connection becomes the centre tap, and the red and the orange are the two 24 V connections with opposite phases.

 

[Nigel Goodwin]

rjenkinsgb you are correct. This is the issue. I have no access to these wires :-(
Nigel Goodwin I did test with everything connected and sending signal. My other sub works fine, this one is dead in the water as I can connect the output to the board.
Diver300 Thanks for the link. I don't know that I'll be able to leverage that one. The connector to the board made use of all 3 wires off the centertap(Red-Black-Red). Assuming I would need similar output from next transformer. Again, novice here, but assuming that black would be ground, and each red is a + 22V output?

Why have the wires been cut? - was it a senseless act of sabotage?, or did the amplifier die, so the transformer was disables to prevent attempted use?.

 

[Lightium]

Just get a new transformer. Any reason not to?

 

[Scaprara]

rjenkinsgb Awesome! Thanks for the assist and additional info. Ordering one now and will follow up with results!