How to connect Sowter 9145 to Bo Hansens DI PCB?

[Koba]

Hi,

I'm building a couple of DI boxes, using Bo Hansens 1975 design (ordered PCBs from Gustav). I need some advice about how I should connect the leads from the Sowter 9145 to the PCB. The tranny has eight leads (yellow, grey, pink, blue, red, brown, white and orange). On the PCB there is markings for pin 1, 2, 3, 4, 5, 6 and 8 for the Lundahl LL1538 (which is mounted to the PCB).

When I compare the data sheets from the LL1538 and the Sowter 9145 my guess is that this might be right:

Sowter 9145 lead to PCB number:

Yellow: 1
Grey:  2
Pink:3
Blue: 4
Red: 5
Brown: 6
Withe: not connected? (Why is there no number 7 on the PCB by the way? Yes, yes, I'm a neebie just trying to learn...
Orange: 8

Or am I wrong here?

PCB illustration: http://www.hansenaudio.se/silk%20V9.jpg 
Sowter 9145 data: http://www.sowter.co.uk/specs/9145.htm
LL1538 data: http://www.canford.co.uk/ProductResources/ig/2735.pdf

Any help is appreciated!

Thanks,
Koba     

 

[Bo Hansen]

Koba,

If I have understand Sowters data sheet, it must be connected as follows:
(configurated as 1:4 /300 ohm to 4,8 kohm)

Red to pcb-6
Orange to pcb-5
Brown and White connected together and isolated. (not connected to the pcb)

Yellow to pcb-1
Pink to pcb-4
Grey to pcb-2
Blue to pcb-3

Transformer case (and maybe if there is a cable to core ground) to pcb-8

Do not mount the transformer case/house in the metall box, it must be isolated.
Please read about this on www.hansenaudio.se/techpage.htm

--Bo

 

[Koba]

Hi Bo,

thanks for your quick reply! I'll go for your suggestion then. I have been checking your website out, lots of good information.
I'll be sure to isolate the transformer from the metal box. Hope it works and that I don't blow the 9145 up.

When you say transformer case to pin 8, do you mean that I should solder a wire from the transformer housing/body to pin 8?
Sorry for my neebie questions here, I hope this might be useful for other builders in the future. 

One more question by the way: I've noticed that you recommend a 3 mm LED. Would it be a problem to use a 5 mm LED?
Didn't see this before I ordered my parts.   

Again; thanks alot! 
Koba   

 

[Bo Hansen]

Koba,

Unless the transformer has an extra wire that is connected to the case and core, you need to solder or screw a cable on the transformer case and connect it to point 8 on the pcb.

5 mm LED is fine, as long as you choose red.
(the reason is the low voltage drop)

You can not destroy the transformer unless it is connected to any point on the PCB that contains dc-voltage.

Please, move this topic to the Drawing Board section and the main topic for "DI-box 1975",  so others can take part of our discussion.
http://www.groupdiy.com/index.php?topic=36569.0

--Bo

 

[Koba]

Thanks, Bo. How do I move the thread?

Still waiting for the PCBs and the trannys. I'm looking forward to getting the boxes together. I really don't know to expect from the 9145. But I hope it will add something to the signal passing through. Didn't fine that much about the sound/characteristics in the different trannys thats possible to use in the 1975 DI. I'll report back when I have put them together.

Thanks,
Koba

 

[Bo Hansen]

Koba,

I do not know myself how to move over one Topic to another section, I think it's the moderator who has to handle this.
Send a question to "Gyraf" which is one of the moderators for this forum.

--Bo

 

[Koba]

Hi there,

I have now received all the parts and put the box together. The lamp works when I turn on 48V, but I get no signal through the DI.
I have checked for soldering bridges, bad connections and so on and I cant find anything wrong.

There is also a black cable from the transformer. This image: http://i25.photobucket.com/albums/c95/fmoscowitz/9145.jpg says that it is 'electro static screen''. Should the black cable be connected to point 8 on the PCB?

Koba







bilde-5 by kobakobakoba, on Flickr