Have Buffalo III with the latest generation Tridents, Placid HD. IVY III, Placid HDBP and TP purchased Lindberg Transformers. Using TP Toslink board direct into the Buffalo III. Placid HD has 5.25 output voltage and 50 Ma. Shunt voltage. Placid HDBP has 15 + and – output voltage and 50 Ma shunt voltage.

Experiencing high AVCC module output voltage on one side of AVCC Module.
QP 3 & QP1 measure 4.37V . QP2 & QP2 measure 3.5V. . D1 has faint glow D2 is normal

The Buffalo III produces great sound in both channels.

Have had the same experience with three new AVCC Modules. It’s obvious something is killing my AVCC Modules.

Per Russ White’s previous advice on this forum, I set up a 3.3 power supply and measured 14 and 16 mills draw into the two AVCC out headers (22 & 7 on page 3 of Buffalo III Application Guide) with no AVCC Module on header. 14 Ma on the side that measures 4.37 MA.
In an e-mail question to Brian, he asked: What is the Placid's output voltage with no load?

Result: Placid HD and Placid HDBP output voltages remain the same when Buffalo III and IVY III are not connected to power supplies.

Brian advised - If you want to measure output voltage offset of IVY III, short +IN and -IN the GND.
Result: Sorting I_IN_L.1, I_IN_L.2 and I_IN_L.3 on the IVY III board (and on the right side) I measured .546V and .246V across the IVY III single ended terminals. I also tried a 1K resistor between the IVY headers and measured no voltage on both IVY III SE terminals.

Photos are: 1.) AVCC Module with measured voltage indicated. 2.) Top of Buffalo III board. 3.) Back of Buffalo III board 4.) Top of IVY III board. 5.) Back of IVY III board.

Seeking experienced Buffalo III trouble shooting advice for solution to this problem.

I have replaced the AVCC model’s LMP7732MA and the two NPN transistors on the problem side of the AVCC module. I lifted the Buffalo III up off the headers – isolating the Buffalo from the IVY III. I have light on both D1 and D2 and 3.45 volts at the output on both sides of the AVCC module (thanks for the suggestion Brian).

I’m going to assume the IVY III is not right and the cause of the high voltage on the LMP7723MA and failure of the NPN transistors. I would like to understand what is not right with the IVY III and repair the IVY III. My first guess is if I replace IC1 and IC2 and IC5 I will have addressed the likely suspects. Could the solution to preventing another blown AVCC module be this simple?

Replaced IC1, IC2 and IC5 on the IVY III. Problem is solved. Buffalo III is flying straight and true.