Hi Russ/Brian,

Need help with an issue that has me stumped.
Some background: I have enjoyed a dual mono Buffalo II with IVY IIIs, MUX, Volumite, Placids and Placid BPs for some time. Recently I had an issue with the Volumite potentiometer and replaced the Volumite with a new one. When it was replaced I found that only the left DAC board will lock on and not the right. A check of the Tridents pointed to a bad 3.3V board. Ordered new sets of Tridents and AVCC modules for both boards and replaced all 8 on both DAC boards.

I just finished putting everything back together and the lock LED will not come on on both channels. Input voltage to both DAC boards is around 5.3 VDC. The lock LED on the MUX comes on. LEDs on all the Tridents, AVCC modules, Placid and Placid BP boards light up normally. Shunt current as measured on the both Placid boards (R3) is about 60mA. I have been using a Squeeze Touch with SPDIF cable. Any clues as to why the boards will no longer lock on to the signal?

Thanks for your suggestion avr300. Just now rechecked the position of 1.2v and 3.3v Tridents on both boards and they are correct. I got the new version of Tridents (v3) and AVCC module (v2.1) on the Buffalo II boards. Unless there are supposed to be any changes in the way they are installed, they are setup in the same position and oriented similarly to the older versions.

Any other thoughts?

Here are the voltage measurements from Tridents and AVCCs:

Left Board:
Module --> In/Gnd Out/Gnd
VDD (A) --> 5.21v 1.174v
VDD_XO (B) --> 5.21v 3.28v
DVCC (C) --> 5.2v 3.28v
AVCC Left --> 5.19v 3.46v
AVCC Right --> 5.19v 3.46v

Right Board:
Module --> In/Gnd Out/Gnd
VDD (A) --> 5.22v 1.179v
VDD_XO (B) --> 5.22v 3.27v
DVCC (C) --> 5.22v 3.29v
AVCC Left --> 5.21v 3.49v
AVCC Right --> 5.21v 3.48v

Edited by user Sunday, December 8, 2013 2:44:38 PM(UTC)  | Reason: Not specified

What I would do was to reduce complexity just for the test.

Go single dac, go single input (omit the mux), go spdif.

Even without firmware chip attached, this configuration is able to play spdif input (beware, 100% volume @output)

Test each dac this way.

You don't need to break the whole thing apart.

Just disconnect the volumite at the Vcc (+ at the vol.board). It should be enough.

Feed each dac with spdif, nothing fancy, "air-wires" will do. Just to check if we can get the boards to lock.


Yes, always good to check with another source.

No, input voltage in range 5.2 to 5.5 is ok.

Are you 100% sure, that the tridents deliver their voltage to the dac board. I know, it's a long shot but it is the most obvious since it's the area that you have upgraded.

Are the tridents soldered to the dac or are they socketed ?

Not really. The numbers you have are spot on.

Something else is missing.

The only thing that comes up right now is polarity of the spdif signal ?? hot to hot and gnd to gnd.

Really need this DAC to work... any other suggestions?

Brian, if so, pls. post the fault and solution here. It's rather interesting.

I have your boards and have set up a test rig, but of course the battery in my meter is dead, so basic tests will have to wait until tonight.