Bo Hansen DI layout

[ruffrecords]

Be sure to get the gold or selective gold versions. The tin is not that good for low voltages. The Molex crimp tool is 638112200. Use the "B" slot.

The only problem with that is how incredibly expensive the Molex tool is. Not justifiable for most DIY users.

Fortunately lower cost ones are available:

RVFM HT-225D Ratchet Action Crimp Tool Ht225d

Cheers

Ian

 

[lele_sakko]

And today my DI starts to make some weird noise..
and i've not moved from yesterday from my desk..
it has some ground noise, intermittent, from the XLR out, and from the parallel out..
The connections are right, the pin 1 of XLR is attached to the chassis, che chassis ground on PCB is connected there too, the jacks are insulated from the box..
the weird thing is that i've used on live for about 3hours, and at home, without any weird noise o problem, and this morning starts that noise..
i try to attach an audio file here..
any thoughts? thank everyone!

 

[Potato Cakes]

Recheck your solder joints. I've had pieces of gear work for a period of time then start having problems and it turned out to be a cold solder joint.

 

[lele_sakko]

thanks, unfortunatly that time isn't a cold solder joint..
i've passed all them and the problem is still there..
voltage are right, and the DI works, but with that weird noise..
Maybe a damaged transformer? i have two pins on the secondary that sounds with tester in continuity mode.. non 2 and 3, a can't remember if 1 and 2 ore 3 and 4..

 

[Potato Cakes]

I would then change out the active components. You can start by replacing both transistors.

 

[lele_sakko]

I would then change out the active components. You can start by replacing both transistors.

Yes, i’ve thinked that too.. next move will be diodes..
I’ve Made an order from eBay for the transistors, in my city there arn’t Electronics shops, so now i can only wait..

 

[Potato Cakes]

You would be best served ordering from a notable electronics distributor. There are a lot of fake parts on ebay.

 

[lele_sakko]

You would be best served ordering from a notable electronics distributor. There are a lot of fake parts on ebay.

Yes, i know, but time for shipping and costs are bigger.. i’ll try if that work with the 10 couple of transistors i’ve brought..

 

[lele_sakko]

Thanks to everyone!
I’ve replaced the two trannies and the weird noises are gone!
Here is my Bo Hansen DI!

 

[Newmarket]

Yes, i know, but time for shipping and costs are bigger.. i’ll try if that work with the 10 couple of transistors i’ve brought..

Yes. It can be very difficult now with few actual outlets and minimum order values or high shopping costs. In UK COC can be okay if you make an order for approx 20 Euro IIRC. Or places selling bits for guitar pedal DIY although stock is not comprehensive and source of components is more difficult to verify.
Bring back the Maplin catalogue

 

[Ricardus]

Thanks to everyone!
I’ve replaced the two trannies and the weird noises are gone!
Here is my Bo Hansen DI!
View attachment 108964

Looks good. Where did you get the enclosure?

 

[egroys]

I just finished a pair of these (one LL1538 and one OEP A262A3E).
They both work but my voltages are wildly different to the spec on Bo's page (save for Lundahl at 6.8k):

The OEP:
6.8k junction=+42.8v DC
3.9k BC560 junction= +39.9v DC

The Lundahl:
6.8k junction= +23.7 DC
3.9k BC560 junction= +8.4v DC

Please advise!

 

[lele_sakko]

Looks good. Where did you get the enclosure?

if i can remember from a shop called Modushop here in italy..

Otherway, my DI starts again to make that weird noises.. i've tried to replace the transistors again, same story.
I've tried to replace the electrolytics condensers, and also the 100nf near the diodes, and the problem is still there..
i can only suppose i have a problem with the transformer..

 

[Bo Hansen]

Hi egroys.

The OEP version is not function at all, because the high voltage in the 6,8k junction, is due to the electronics not drawing any current, you have obviously done something wrong, with any component or transistor that is in the wrong place or any component leg that is poorly soldered.
If you use an LED, it is important that you turn it in the right direction, if you do not use an LED, then there must be a wire link in the holes marked LED.

The Lundhal version have ok voltage in the 6,8k junction, but wrong operating point in one of the transistors.

What kind of transistors are you using, are they in the right place, are the pins in the right direction.
Do you have the right values for the resistors, and are they in the right place.

Are you using our real circuit board from Volker Meyer, or from someone else who illegally sells their own version of the circuit board.

Can you show photo of your assembled circuit boards.

--Bo

 

[Bo Hansen]

if i can remember from a shop called Modushop here in italy..

Otherway, my DI starts again to make that weird noises.. i've tried to replace the transistors again, same story.
I've tried to replace the electrolytics condensers, and also the 100nf near the diodes, and the problem is still there..
i can only suppose i have a problem with the transformer..

lele_sakko,

I can't open your previous attachment sound file, so I can't hear what kind of noise you have.

But it seems that the DI box works otherwise except for the noise that comes and goes.
When the noise comes, is something connected to the instrument input, or is the jack short-circuited with its internal break function ?

I assume you are using a metal casing/box and not plastic.

What is the Di-box XLR connected to, and is the Phantom poweing from ?

Can the noise/disturbance come from outside the DI-box, from something in the room you are in, have you tried whether the disturbance occurs in another room or not ?

Can you show a picture of what the DI box looks like on the inside.

--Bo

 

[egroys]

Hi egroys.

The OEP version is not function at all, because the high voltage in the 6,8k junction, is due to the electronics not drawing any current, you have obviously done something wrong, with any component or transistor that is in the wrong place or any component leg that is poorly soldered.
If you use an LED, it is important that you turn it in the right direction, if you do not use an LED, then there must be a wire link in the holes marked LED.

The Lundhal version have ok voltage in the 6,8k junction, but wrong operating point in one of the transistors.

What kind of transistors are you using, are they in the right place, are the pins in the right direction.
Do you have the right values for the resistors, and are they in the right place.

Are you using our real circuit board from Volker Meyer, or from someone else who illegally sells their own version of the circuit board.

Can you show photo of your assembled circuit boards.

--Bo

Edit: I figured out the issue with the OEP but can’t seem to find the issue with the Lundahl. On to changing transistors

I am indeed using Volkers boards, Fairchild BC550B, and OnSemi BC557B so the pinout is the same as printed on the board. I may try an OnSemi BC547B in lieu of the 550C
I will triple check resistors but I am 99% certain they are all correct.
I am using an LED and it is lighting up when it receives phantom power.
I am getting continuity beeps on all traces but will triple check this--unfortunately the boards had several pads that tore out when I was clipping leads, more than I have ever experienced.

 

[lele_sakko]

lele_sakko,

I can't open your previous attachment sound file, so I can't hear what kind of noise you have.

But it seems that the DI box works otherwise except for the noise that comes and goes.
When the noise comes, is something connected to the instrument input, or is the jack short-circuited with its internal break function ?

I assume you are using a metal casing/box and not plastic.

What is the Di-box XLR connected to, and is the Phantom poweing from ?

Can the noise/disturbance come from outside the DI-box, from something in the room you are in, have you tried whether the disturbance occurs in another room or not ?

Can you show a picture of what the DI box looks like on the inside.

--Bo

Hi Bo, thanks for your reply!
Well, the noise is still there also without anything connected to the DI, and it have a shorted input jack.. I am using a metal case, the DI is connected to a Focusrite 2i2 and the phantom comes from the audio interface..
the noise comes from the DI, i’ve tested that in many places and with different phantom power sources but the noise was still there..
The ground was correct, the pin 1 ok xlr connects to the chassis, with the chassis cable from the pcb..
the strangest thing is that the DI worked well, i’ve played a live with that, the sound guy tells me that i have the better bass sound ever, i’ve used at home to play, and a day without the di was used or moved it starts that noise..
I attach you the sound and some pics i have right now..

 

[Murdock]

Edit: I figured out the issue with the OEP but can’t seem to find the issue with the Lundahl. On to changing transistors

I am indeed using Volkers boards, Fairchild BC550B, and OnSemi BC557B so the pinout is the same as printed on the board. I may try an OnSemi BC547B in lieu of the 550C
I will triple check resistors but I am 99% certain they are all correct.
I am using an LED and it is lighting up when it receives phantom power.
I am getting continuity beeps on all traces but will triple check this--unfortunately the boards had several pads that tore out when I was clipping leads, more than I have ever experienced.View attachment 109104View attachment 109105

It looks like the electrolytic capacitor next to the Lundahl transformer is installed with the wrong polarity...

 

[Bo Hansen]

Hi Bo, thanks for your reply!
Well, the noise is still there also without anything connected to the DI, and it have a shorted input jack.. I am using a metal case, the DI is connected to a Focusrite 2i2 and the phantom comes from the audio interface..
the noise comes from the DI, i’ve tested that in many places and with different phantom power sources but the noise was still there..
The ground was correct, the pin 1 ok xlr connects to the chassis, with the chassis cable from the pcb..
the strangest thing is that the DI worked well, i’ve played a live with that, the sound guy tells me that i have the better bass sound ever, i’ve used at home to play, and a day without the di was used or moved it starts that noise..
I attach you the sound and some pics i have right now..

lele-sakko,

You have a reversed electrolyte, the one closest to the BC550 transistor. this is the 10uF electrolyte for the BC550 bias/operating point.
Replace this and turn the new right, don't use the old one.

--Bo

 

[Bo Hansen]

Edit: I figured out the issue with the OEP but can’t seem to find the issue with the Lundahl. On to changing transistors

I am indeed using Volkers boards, Fairchild BC550B, and OnSemi BC557B so the pinout is the same as printed on the board. I may try an OnSemi BC547B in lieu of the 550C
I will triple check resistors but I am 99% certain they are all correct.
I am using an LED and it is lighting up when it receives phantom power.
I am getting continuity beeps on all traces but will triple check this--unfortunately the boards had several pads that tore out when I was clipping leads, more than I have ever experienced.View attachment 109104View attachment 109105

egroys,

Start by measuring across one of the two 100k bias/working point divider resistors, (closest to the base of the first transistor) both should be approximately +12 volts across each other.
If you do not have this, the half operating point voltage will not be correct on either the first or the second transistor.
If this is the case then check that these resistors are indeed 100k and that the 10uF electrolyte is ok.

But if this bias voltage is correct, then you should also get approximately +12v across the first transistor's emitter resistor of 100k, if you don't get this, change the transistor and check the 100k resistor as well.

If the first transistor emitter voltage is correct, then measure the voltage across the second transistor emitter resistor 3k9 which should also be around +12v, if it is not this, then change the transistor and check the 3k9 resistor.

PS! all +12 volt measuring points consider that the supply voltage above the 100uF is +24 volts, if it is not this, shall instead all "12v voltages" should be about half of the existing supply voltage.

--Bo