Phantom Power Issue

[silvershark]

Hi there

I'm new to the world of SSL desks and have just bought a cut down 24 channel 4000 Series desk. The desk is lovely and I am slowly learning all about it however
I am having some problems with the Phantom Power. The lights are on for all 4 voltages on the desk (i.e. 48v/+18V/+11v/-18v) but there is nothing getting to the mics - or at least I am not getting any signal through the desk.

I have checked using dynamics and powered condensers and they are fine but nothing with a standard phantom power condenser

Am I missing something - or is there a problem with the desk?

Thanks in advance for any assistance it's greatly appreciated

Cheers
Grant

[sintech]

On a standard E series, the Gain pot has a 48V switch combined, think it's down for 48V and Pull up for off (can't quite remember)

'Radio DK' E series, has no activation on the channel, but a global 48v switch on the Centre.

The G series the 48v button is where the 'Pad' is on the E series.

[silvershark]

Hi Sintech

Thanks for reply

It's a G-Series so has the 48V button

We've just done some more testing and it looks like although the 48v light is on there is no voltage coming through. Although there is a really nasty buzz when you plug a condenser in and bring up the fader

I am thinking that it may be a good idea to get a tech in for the day to check it over and also make sure everything else is ok. I've had a hell of a job with the DL wiring as well..

Thanks
Grant

[sintech]

Hi, if you have VU's you can borrow the 250v regulator card and pop it into the 48v position.  If the LED is on, some kind of voltage must be present, you can measure this at the patch bay.

[sintech]

Grant, out of interest who supplied your cut down G?

[silvershark]

Hi

I'll try that.

On the power supply there are five LEDs one for each of the following voltages;
+20/-20/+13/+48 and +250

All are lit except the 250 one. Does anyone know if this should be lit? I'm guessing it should and perhaps this may have something to do with he problems I'm having?

I bought the desk from another engineer in the same studio complex as I'm in but he got it from AES

Thanks
G

[sintech]

The 250v is just for consoles fitted with Plasma meters.

You should have a 250v on/off switch by that LED for a UK supply, apart from the Jap version (661J) it's hidden behind the removable front panel.

[silvershark]

Ok

I have VUs not plasmas but there is no switch beside this but I think the desk might have originated from Japan actually. Do you mean the power supply front panel?

Can anyone recommend any techs that are based in London area, I'm in SE London

Thanks

[sintech]

Yeah, the power supply front panel.

[silvershark]

Ok I'll check that out? Do you think the out be messing with the Phantom Power and causing the problems I'm experiencing

[sintech]

The 250v should be off for your console with VU meters.

If it’s 661J you won’t be able to “borrow” the 250v regulator as it’s a different arrangement to the standard supply.

The 48V regulator circuit is independent from all the other rails, so whatever that’s pumping out is fed via the 48v switch to the mic lines… so very passive in terms of the console end.

[sintech]

Jap 661 looks like this:



Standard version has this arrangement:

[silvershark]

That looks like it but I've left studio know so ill need to check if it is a 661

Thanks very much

[PelleG]

Check that you have ground connected to your mic panels. Phantom needs the ground.

[silvershark]

HI

Another question on this

I have checked everything and digging around the patchbay I have discovered that there is what appears to be an earth wire connected to input one on the Mic Lines on the patchbay. This is not connected to anything at the other end. Could this be causing the problem I am having? What should this be connected to?

Many thanks
G