Pass ONO or XONO PCB???

[blue lander]

I decided to follow Ralph's schematics to build a Xono, but I'm basically doing it p2p since I'm cheap. I just finished one channel and nothing's working. I'm getting .300v across R53, but I get 1.1v across r67. I can't get any voltage across R28. The LED I'm using is from Radioshack, 2v 20ma. I get 1.7v across it.I must have miswired something, but I checked everything over several times. Any ideas what to check?

[blue lander]

Do'h, found the problem 30 seconds after I posted. Forgot to connect a leg of Q6. It's making music now.

edit: And now I've killed it again. Something started smelling after about 10 minutes, now the board is pretty much dead. The LED still comes on but I don't get that "thump" on the output I was getting before

[blue lander]

I've replaced q16, q17, and q6, the board's still dead. I get 1v across r67 and r53 and .35v across r28 and r27. Everything seems fine, but I don't get any output from the board. There isn't even a 'thump' on the scope on turnon any more. Anything else I should check?

[amhlee]

I have a only limited number of Ono Pcb left by my last project. Please contact me if interested.

[blue lander]

I managed to get my board up and running again. I'm getting quite a bit of buzzing, though. I'm using a pair of SMPS to get +/-30 volts, so they may be the culprit.

[amhlee]

Here is mine

[image]http://www.photo100fun.com/attachmen...G5pvMMcJE7.jpg[/image]

[h_a]

I'm getting quite a bit of buzzing

The Ono uses a cap-multiplier to filter the frontend voltage and the 2nd stage isn't that sensitive to power supply noise.

Also, depending on your make of the SMPS its noise should be outside of the audible range (40kHz or so).

So it might be worth to have a look at the grounding scheme first.

Hannes

[spzzzzkt]

If anyone is interested I've just listed a set of fully populated Stens Xono boards in the swapmeet forum.

R.Stens X-Ono boards populated - Melbourne AUS

thanks
Paul

[Marra]

Took the top off my Xono built with Ralf Stens pcb's to check the bias setting. I reset to 0.35v it had drifted a bit; when I checked the dc offset it was fluctuating wildly; +- 100mv plus on both sides of the 10uf output caps and could not be adjusted much with the trimmers. Is this something to be concered about? Any advice/pointers as to what to check would be much appreciated. TIA.

[blue lander]

Originally Posted by h_a

Also, depending on your make of the SMPS its noise should be outside of the audible range (40kHz or so).

So it might be worth to have a look at the grounding scheme first.

Hannes

You're right. I used a star grounding configuration and the buzz went away completely.

Behold the world's ugliest phono stage:

I've only completed one channel so far, MM only without the balanced part since I don't need it. For the chassis I used a steel case used to transport backup tapes. I'm going to drill holes for power and the RCA connectors over the weekend. It's bisected down the middle, I'm putting the unregulated power supply on one side and the xono boards and regulators on the other. The power supplies are two 400ma 48 volt SMPS's per channel. I have a ton of these laying around. I'll add another two for the second channel, and later when I build the MC stage I'll add a seperate SMPS and regulator for those as well. Ultimately I'm going to use Salas shunt regulators, but for now I'm just using LM317's to regulate down to +/- 30v.

One channel is only pulling about 30ma at 30 volts, so I have voltage and current to spare. Would it be worthwhile to use a capacitor or CRC network between the SMPS and the regulator to smooth out and stiffen the power supply?