Genelec 7060b transformer taps needed

[camarada78]

I have a Genelec 7060 subwoofer with a dead transformer (primary opened) and it would be very costly to get a new one from Genelec here in Rio. Are there any alternatives?

I dont know the taps, but It seems to be around 50v/0/50v and 15v/0/15v toroidal with 6(!) primary taps (for 115-240v and maybe something else. Anyone knows where to search for this part? i'm out of ideas. there is no schematic.

 

[NoisyIndividual]

I have one here and have just measured the secondaries unloaded.

It is 17.7v 0 17.7v
40.5v 0 40.5v.

So probably 15v / 35v or thereabouts.


This is actually a 7060A model.
I have just ordered a replacement power amp kit, since the STK modules are unobtanium, and Genelec upgraded to a TDA based board for the 7060B.
The kit comprises the power amp and heatsink/grille from a 7060B, so it looks like the power supply will be the same in both these versions.

 

[camarada78]

17+17 is what i thought since its using 7815/7915.

but 40v x 40v is a little less than i thought, the board is written +52v/-52v.

But that makes sense since its using a STK 433-130 which is rated for 44v ideal vcc voltage.

Maybe its maximum voltage on the board.

the circuit is very simple there, its mostly a linear rectifier, a STK 433-130 (which ebay is full of it) and another rectifier with 78/7915 regulators for 15+15.

 

[NoisyIndividual]

You cannot buy an STK433-130 on Ebay or anywhere else that isn't a fake.

It will blow up very shortly after you install it.

 

[camarada78]

interesting to know.

Would you happen to know why there are 6 taps on the primary to make the 220v instead of the traditional 3 ou 4?

 

[NoisyIndividual]

I have no idea, and it doesn't really matter since you won't be looking for the exact replacement.

Just get a toroid with the correct primary for your country.

 

[camarada78]

yea, here in Rio its 127v. So i would kill the 220v switch but it really doesnt matter. I think i'll order a 40+40/15+15 3a transformer and give it a go.

Thanks a lot for that info.

 

[NoisyIndividual]

40 0 40 is higher than the transformer I have here.
35 0 35 and 15 0 15 is more likely what they used.

 

[camarada78]

noted. thanks.

 

[NoisyIndividual]

Just got another unrelated 7060A in today.

Unloaded, these transformer secondaries are 18.1v 0 18.1v and 41.6v 0 41.6v.
Mains voltage is 245.5v at the moment, so this is at the upper limit of what's to be expected.

 

[camarada78]

Hello again, thanks a lot for your help.

we've managed to make it work with a new transformer following the original specs (the thermal fuse was blown), we put it with the original stk433 but it is distorting a lot. loud humming after 5-10 minutes working. unusable.

We narrow it down to the 433 and... we've installed these generic ebay stk 433 and none worked. not even a blowing up sound. dead silent. i wonder if these fakes have even the same pins.

What is this power amp module you got? is it straight from genelec?

 

[NoisyIndividual]

It is a "kit" supplied by Genelec comprising the Grille and amplifier PCB.

In the UK you can get them from HHB, UK distributor, but they are rather expensive.
"P/N 7060B-702 Amplifier Kit with Grille for 7060B" is what HHB call it.

It took several weeks to get mine.

 

[camarada78]

ok cool. genelec here in rio wont sell us spares. and they are charging around 750usd to fix this thing.

i wonder if I figure what the 10 pin (J5 connector) do i could use another entirely different amplifier. no schematics for this unit yet

 

[NoisyIndividual]

Its $450 - $500 US for the kit here retail, maybe Genelec Rio just fit the kit rather than sell you it.

 

[Motobias]

i have the same issue on a 7070a subwoofer.
would you expect an identical transformer with more current in there ?
i noticed that the driver is dual voice coil and there are two stk modules in there.

 

[Motobias]

since there was no answer so far i'll let you know what i found out.
first of all the output AC! voltage of the transformer doesn't translate to the same rectified and filtered dc voltage. if you measure with a proper rms meter on the unloaded transformer taps, you'll need to multiply that voltage by squareroot of 2 (1,41...something).
So 35V AC equals to roughly 50V DC rectified and filtered.

Based on the power rating of the sub that equals to twice a 7060 and looking at my amp module, i'm making the assumption that i'm dealing with two 433-130 modules.

the other rail(s) are based on the mentioned 78/7915 regulators that will take up to 30V

so a transformer up to 40v and 17V AC should be doing fine !

i recently got a harman kardong avr transformer gifted that might do the trick.

will do further measurements when i get back home.

I found this list of stk modules in case someone can reference

STK433-090-E STK433-100-E STK433-120-E STK433-130-E
Output 1 (10%/1kHz) 80W×2 channels 100W×2 channels 120W×2 channels 150W×2 channels
Output 2 (0.4%/20Hz to 20kHz) 50W×2 channels 60W×2 channels 80W×2 channels 100W×2 channels
Max. rated VCC (quiescent) ±54V ±57V ±65V ±71.5V
Max. rated VCC (6Ω) ±47V ±50V ±57V ±63V
Recommended operating VCC (6Ω) ±33V ±35V ±40V ±44V

 

[mihatsu]

since there was no answer so far i'll let you know what i found out.
first of all the output AC! voltage of the transformer doesn't translate to the same rectified and filtered dc voltage. if you measure with a proper rms meter on the unloaded transformer taps, you'll need to multiply that voltage by squareroot of 2 (1,41...something).
So 35V AC equals to roughly 50V DC rectified and filtered.

Based on the power rating of the sub that equals to twice a 7060 and looking at my amp module, i'm making the assumption that i'm dealing with two 433-130 modules.

the other rail(s) are based on the mentioned 78/7915 regulators that will take up to 30V

so a transformer up to 40v and 17V AC should be doing fine !

i recently got a harman kardong avr transformer gifted that might do the trick.

will do further measurements when i get back home.

I found this list of stk modules in case someone can reference

STK433-090-E STK433-100-E STK433-120-E STK433-130-E
Output 1 (10%/1kHz) 80W×2 channels 100W×2 channels 120W×2 channels 150W×2 channels
Output 2 (0.4%/20Hz to 20kHz) 50W×2 channels 60W×2 channels 80W×2 channels 100W×2 channels
Max. rated VCC (quiescent) ±54V ±57V ±65V ±71.5V
Max. rated VCC (6Ω) ±47V ±50V ±57V ±63V
Recommended operating VCC (6Ω) ±33V ±35V ±40V ±44V

My 7070a toroid failed as sell. Did you ever find the replacement toroid?

 

[NoisyIndividual]

This is a bit of a long shot, but the Genelec 1029A toroid transformer has a built in non resettable thermal fuse on the primary.
Possibly this is to ensure your house etc doesn't burn down should it fail slowly.

You might have a look to ensure your toroid isn't equipped with the same, which you could theoretically bypass, if you don't mind the risk of your house etc burning down.