Broken transformer on Carlsbro GRX7

[OrganiK]

Re: Broken transformer on Carlsbro GRX7

Thanks for all the help! much appreciated

[budm]

Re: Broken transformer on Carlsbro GRX7

Yes you can, just wire them up with correct phase.

[OrganiK]

Re: Broken transformer on Carlsbro GRX7

You don't need 2 secondaries, you need a center tapped secondary

I know but can't i make one with a a center tap with a transformer that has 2 identical secondary windings?

[budm]

Re: Broken transformer on Carlsbro GRX7

you don't need 2 secondaries, you need a center tapped secondary

+1

[R_J]

Re: Broken transformer on Carlsbro GRX7

You don't need 2 secondaries, you need a center tapped secondary

[OrganiK]

Re: Broken transformer on Carlsbro GRX7

+ and - 70v for that amp .....https://music-electronics-forum.com/...ad.php?t=19136

Nice one, so then i would need a transformer that has 2 secondarys with an output of about 50Vac each correct?

[petehall347]

Re: Broken transformer on Carlsbro GRX7

+ and - 70v for that amp .....https://music-electronics-forum.com/...ad.php?t=19136

[OrganiK]

Re: Broken transformer on Carlsbro GRX7

You should try and find out what the voltage should be, if that is not the original transformer, 43vac is meaningless. What is the voltage on the main caps?
If the 43vac is correct you would have 60 vdc across the + of one capacitor and the - of the other, so about 30 volts across each capacitor to ground.
This must be the way they are using the transformer.

The second picture is how it is normally done, so maybe the customer broke the center tap wire completely off the transformer?

The caps are rated at 80VDC so its a bit high for 30 right? but maybe since its old school they like to over engineer stuff a lot, dunno.

If it was 43Vac on either side it would give about 56Vdc for each cap that makes more sence for the 80VDC on the caps. we also know that its a 150W x2 amp at 2omh so that would need a voltage of about 17Vac = 24.5Vp so that fits better with it being 43Vac total.

Thanks a lot for you time and patients by the way

[R_J]

Re: Broken transformer on Carlsbro GRX7

You should try and find out what the voltage should be, if that is not the original transformer, 43vac is meaningless. What is the voltage on the main caps?
If the 43vac is correct you would have 60 vdc across the + of one capacitor and the - of the other, so about 30 volts across each capacitor to ground.
This must be the way they are using the transformer.

The second picture is how it is normally done, so maybe the customer broke the center tap wire completely off the transformer?

[OrganiK]

Re: Broken transformer on Carlsbro GRX7

I see two wires had spade connectors on them, I am guessing they connected to the power switch originally, What about the larger secondary wires, were they just floating around in the mixer and not connected to the bridge? too bad the customer played with it first, that's never a good sign. I wonder if this is the original transformer?

Non of the wires where connected, I put the connectors on them wire.

Yer I also wondered if someone had put a different transformer in it.

So where did you get the 43V on the secondary before? was it just a guess?

Edit: Sorry my bad i was just being stupid and could not read the sticker properly it says 43V 3 Amps on it...

and the caps are doble that, so could well be the right voltage. So do you think i should just try and fit a 2x 43V 150VA Transformer and cross my fingers? lol

[R_J]

Re: Broken transformer on Carlsbro GRX7

I see two wires had spade connectors on them, I am guessing they connected to the power switch originally, What about the larger secondary wires, were they just floating around in the mixer and not connected to the bridge? too bad the customer played with it first, that's never a good sign. I wonder if this is the original transformer?

[OrganiK]

Re: Broken transformer on Carlsbro GRX7

are those caps in parallel ?

no they are, there is one for each power rail

[OrganiK]

Re: Broken transformer on Carlsbro GRX7

would spike the secondary then blow the fuse most likely .

what from the inrush current? i though that only happend on caps or motors, im really not sure so please correct me if im rong

[OrganiK]

Re: Broken transformer on Carlsbro GRX7

I would guess blue and green are the secondary 43 volts, Brown and pink 240vac with the orange and (yellow/red???) connected together. and now the winding between the pink and orange is open. You could supply 120vac to brown and orange to see if you get 43vac for the secondary

yer that's what i thought, Still i recon you right about there should be a center tap on the secondary tho...

Havent got means of getting 120vac... i might be able to borrow an old building transformer, that should do right?.

Still dont quite understand why it would blow the fuse by putting more volts on it if there isn't any load on the secondary

[petehall347]

Re: Broken transformer on Carlsbro GRX7

would spike the secondary then blow the fuse most likely .

[OrganiK]

Re: Broken transformer on Carlsbro GRX7

The thinner wiring should be the primary, if it's got a dual 120VAC primary and putting 220V on one of course it would blow the fuse.

Even if there is no load on the secondary? would a single primary winding not have a high impedance when there is no current flowing though the secondary?

[petehall347]

Re: Broken transformer on Carlsbro GRX7

i would do the 120v also to find secondary voltage and further testing . been there done that .

[R_J]

Re: Broken transformer on Carlsbro GRX7

I would guess blue and green are the secondary 43 volts, Brown and pink 240vac with the orange and (yellow/red???) connected together. and now the winding between the pink and orange is open. You could supply 120vac to brown and orange to see if you get 43vac for the secondary

[petehall347]

Re: Broken transformer on Carlsbro GRX7

pic 2 post 5 should clear it up .spades go to bridge .

[petehall347]

Re: Broken transformer on Carlsbro GRX7

are those caps in parallel ?