Hi Russ

is a new PCB available?

Thank s

Hello, Russ
I have exactly the same problem as avr300.
Do you prefer first

http://www.twistedpearaudio.com...at-output.aspx#post18992

or the second solution to the ripple problem.

http://www.twistedpearaudio.com...at-output.aspx#post19010

Placid HD with ripple I have is about 6mVpp(low frequency) on 5.25V DC output, input ripple is about 400mV p-p and this one is for Buffalo III. Current used is about 520mA (about 60mA shunted). Trafo is PCB type HAHN 2x9V(but output is 2x11.7V) 2x15VA and I only using one trafo output for the Buffalo. The other is for a second Placid HD (5V DC) with much smaller current demand so it's not critical(maybe).

In the DAC box I have 4 trafos:
1) 2x9V (2x15VA) for 2XPlacidHD - Buffalo and Acko reclocker board
2) 2x15V (50VA) for Placid HDBP - IVY board
3) 2x9V (2x15VA) for DIYINHK tps4700 dual power supply - remaining power supplies for Acko reclocker board
4) 2x9V (2x8VA) for arduino board and one free output (for now)

This is a temporary box.

DAC box is earthed but I'm not sure should I connect power ground(s) to the same point(earth) and from which point because of many power supplies with grounds interconnected.
Arduino controller has isolated ground from the Buffalo by TI iso1540. Display used is Noritake VFD CU20045SCPB-W5J.

Regards.

I would start with just a larger trafo and see if it is enough. One half of a 15VA trafo for a Placid/Buffalo is too small.

Just substitute the CLD with a (calculated) resistor.

Just be aware that the current going through the LED will change when you adjust the Vout. It's not a problem for me, I don't adjust the Vout - it just sits there @+-15V ( and 5V2)

Don't rush upgrading the main caps. 10.000uF is more than enough. I just had the caps.

Edited by user Wednesday, February 5, 2014 5:54:46 PM(UTC)  | Reason: Not specified

Hi,

will every placid HD have benefit from bigger trafo, or it is just those that are affected because of config parameters (Vout, shunt current, ...)
I'm trying to find out an oscilloscope to measure this, but would upgrade trafo's anyway.

Would go with next change from your site:
1 pcs 2x9V (15VA) -> 1 pcs 2x9V (30V) [secondariness in parallel] for Buffalo III
1 pcs 2x15V (30VA) -> 2pcs 2x15v(30VA) or 1pcs 2x15V(50va) [secondariness in parallel] for Legato

Is this only change that you are recommending for current Placid HD (BP) until new version is available?

Thanks in advance

I've been busy lately so I only had time to try double the secondaries(no changes at all) and after that changed the main cap to 22000 which reduced the ripple on output down to about 2mVpp at least in lower frequency band.
Now I see that Russ redesigned the placid's so we will have a chance to try out complete solution.

Edited by user Wednesday, February 12, 2014 3:36:34 PM(UTC)  | Reason: Not specified

Hi:

Do the marking in red indicate connection points for the resistors and capacitors (including polarity) correctly?

Best regards,

Resistors have no polarity.

The cap on the negative side (- side) has to be turned 180 degrees.

Remember, when you're dealing with negative polarity, GND is "+" and output is "-". That's why you have mixed up orientation of those caps on the negative half side.

If I understand correctly - new Placids will have only a few parts changed compared to previous one?
I just got my placid kits recently and haven't started assembling them yet. Is there a chance I can somehow order new PCBs with a few new parts instead of whole kit once it's available?

That's not the way I read the question.

AlexT has an old kit (board and a bunch of components not yet mounted). Recently bought and not build yet.

He want to buy the new board, adopt the components from the old kit and add the remaining.


That's all comes down to the BOM of the new kit. Time will tell.