hello
I have a related issue like Henri in two differently configured BIII/Legato/sidecar/4xs/pdif based dac´s:
dac A:
when I hook up s/pdif sources to input 1 and 2 which are configured for consumer lvl
they both work fine if both sources are powered on
sources are 2 different consumer lvl players and swapping inputs changes nothing, so it´s not source related
if source is hooked up to 1 with open input 2, or souce 2 is powered off, signal doesn´t lock properly
same with 2 live and 1 open, or unpowered
if I remove cables from rca plug to pcb on 2, 1 works fine and vice versa
sidecar pcm selection is powered with separate switch feeding I2C header 3,3 vdc routed to "b" on sidecar
this works just fine, independant of s/pdif problem
ac gnd goes to chassis back aluplate and all other pcbs connectors etc are isolated from chassis aluplate
I´ll get back to dac B later

best
Leif

Edited by user Wednesday, April 11, 2012 6:44:14 AM(UTC)  | Reason: Not specified

That's exactly what I also want to know.
grts
Henri

There is nothing happening other than two guys with real full time jobs. We can't watch the forum all the time. :)

Each input into the SPDIF 4 is exactly the same. I would suspect there is likely a GND loop issue.

I would experiment as you are doing.

Some sources will not handle transformer coupling well, and you may want to bypass the transformer for those sources. To do that you must remove the transformer (so that you don't load the secondaries) and replace it with 2 wires going from the primary pads to the secondary pads.

Cheers!
Russ

Edited by user Friday, April 13, 2012 6:45:26 AM(UTC)  | Reason: Not specified

I don't honestly remember. I don't have one on hand at the moment to test.

hello B
you´ve got mail with pictures
best
Leif

ok will do
but the other dac is done like you say
the power connections are good , right?
best
Leif

The leads to the Exa seem very long as well,
Ed
(forget my former post, I see now you did it on purpose)

hello folks
re-positioned BIII and L3 straight behind s/pdif board so ribbon cable to sidecar is less than 2 inches and without twists or bends
sidecar is soldered straight on to BIII dig in header
I2S cables are much shorter
still same problem
single input to s/pdif 1 with open unconnected s/pdif 2=unstable lock, but if I gnd minus on input 1 to alu backplate which is hooked up to ac gnd, lock is stable
If I repeat procedure on input 2, no effect of minus to gnd
if both sources are hooked up to s/pdif 1&2 and both are powered , both lock perfectly
Leif

Yes, I use all 4 sources and they are typically all on at the same time. Did you try not using transformer coupling as suggested?

Make no difference for me whether any are off or on.

It really makes no sense that one being off would create issues. I am a bit baffled with that one.