Another "can I use this transformer?" thread

[rodolfo]

silver1omo see you inbox please

 

[AudioSan]

this is a 4x21V + 2x15V transformer. two and two sec. are internaly wired in series.
then you get 2x42V and a midpoint betwin the sec. where you get 2x21V
black is sentertap. the blue-black wires are the midpoint betwin those 2 sec. red-black wires are 2 sec in series

 

[silver1omo]

Thanks AudioSan, that was my guess, and really needed confirmation

 

[silver1omo]

this is a 4x21V + 2x15V transformer. two and two sec. are internaly wired in series.
then you get 2x42V and a midpoint betwin the sec. where you get 2x21V
black is sentertap. the blue-black wires are the midpoint betwin those 2 sec. red-black wires are 2 sec in series

What do you think of separating the secondaries to get 2x 21v-0-21v?

 

[gootee]

What do you think of separating the secondaries to get 2x 21v-0-21v?

It looks like maybe it was made for that.

What does the PCB tell you about that?

And what does it tell you about current capacities?

 

[silver1omo]

It looks like maybe it was made for that.

What does the PCB tell you about that?

And what does it tell you about current capacities?

I no longer have the amp PCB... The AC PCB has a 4A fuse (T4AL250) and the amp PCB had a couple of 5A fuses (T5AL250).

 

[AudioSan]

What do you think of separating the secondaries to get 2x 21v-0-21v?

no. that will require opening up the transformer and cut the winding at the centertap and split it in two.

 

[silver1omo]

no. that will require opening up the transformer and cut the winding at the centertap and split it in two.

I took a close look, won't need to cut the winding, just de-solder a pair of wires.

 

[AudioSan]

okei. so there is 4 sec. solderd togheter on terminals on the bottom of the transformer?
in that case, it's all good

 

[silver1omo]

One red, one blue (pair of wires) and one side of the black (pair of wires) are a yellowish emmanel wire the other red, blue (pair of wires) and side of the black (pair of wires) are redish emmanel wire.So it looks like it does have 4 secs and can be split to 2 center tapped 21/0/21.

 

[AudioSan]

to check that. you can massure resistance from red to red. and from red to the solder point you think is the centertap solder(there you think you can desolder it). and see if the resistance is half of the resistance from red to red.

 

[tinitus]

I have the same issue now
trying to remove a 120-220-240V mains selector switch
tricky, but with 3 voltages and only 4 wires I reckon it have to be one wire with taps

will try and see what happens if I remove a wire from the switch

 

[TonyTecson]

I just realized that the PCB has markings on the mains.
Blue 0v
Brown 110v
Orange 240v
White 220v
Red 127v

So I'm guessing it is a multi-tap. I'll make a dim bulb tester and see what I get.

Thanks guys.

did you test with the leads disconnected to the board? if that is the case then the primary is easy, just use the blue and the orange wire and you're done...

 

[tinitus]

ok, before cutting I measured 450ohm at 240V mains switch
after cutting the blue wire from selector, still measure 450ohm
and 220V is gone from selector
seem fine so far

 

[tinitus]

checking secondary voltage, and still 19-0-19V
cutting the red wire, and measure 450ohm on main switch
power on and voltage check
and still measure 19-0-19V

 

[TonyTecson]

good job....

 

[tinitus]

thanks
not so easy to find nice small trafos these days