my 2408mk3 freaks out when i turn on my DM24

[kkarney]

i've got: a MOTU 2408mk3 with two TDIF connections (A & B) and an ADAT (C) . these are connected to a Tascam DM24. i use Sonar Pro 6. i sync it all w/ an Apogee Big Ben. (i also have a Presonus Digimax, but this problem occurs whether or not it's plugged in.)

i have happily used this setup for about 3 years (give or take a year). about 10 months ago, i started to have an intermittent issue with the TDIF meters (A & B) on the 2408mk coming on (erratically) when there was no signal going in or out. in Sonar, those channels that are "freaking out" are totally pinned, making recording impossible on them.

i would reboot and start everything up again and it would usually be fine. (i'd say the freakage happened about 30% of the time, but always went away after a reboot/power cycle or two.)

as time goes on, the problem has gotten worse and worse. at this point, i have the issue 100% of the time. if i wait long enough after powering on, it will sometimes go away for a little while, but always comes back after a few minutes. i am now unable to record on any of the TDIF channels (thereby making live band recording impossible).

this phenomenon goes away immediately when i power off the DM24 (and comes back when i power it on). of course, i can't record when the DM24 is off (since i use it for the 16 XLR inputs and monitoring). so it's definitely related to the DM24 somehow...

i have tried swapping TDIF cables (and even ADAT even though that bank seems OK); swapping BNC cables (word clock); reseating the PC424; changing the sync settings so that the DM24 is the master; also tried making the 2408mk3 master; updated firmware on the DM24. nothing seems to help.

the thing that really puzzles me is how this issue just got steadily worse and worse rather than happening all of a sudden.

does anybody have any ideas? this is killing me.

[Malcolm Boyce]

If you haven't already, strip things back to a single TDIF connection between the two devices. If you have swapped each of the TDIF outputs of the DM24, around with all three TDIF inputs of the MOTU with the same results no matter the settings, the next easy step in troubleshooting is to check either the DM24 with another device that accepts TDIF, and/or the MOTU with another device that sends TDIF.

A gradual loss of stability over time indicates something likely wrong hardware wise, as opposed to a settings issue.

Do you have the Lightpipe connection made and active to and from the DM24 and MOTU? Does it work in both directions? This would indicate to me that both devices are synced properly. That would lead you to it being a problem with the TDIF interface(s).

[kkarney]

thanks for your reply!

yes, i've tried a single TDIF with the same results... and it's fine with the ADAT only (i do have ADAT going both in and out).. so it sure does look like a TDIF hardware problem.

now i've gotta try to find somebody with a TDIF device...

a couple things i forgot to mention in my original post:

-- this issue only seems to affect input (from DM24 to MOTU to Sonar). output (e.g. mixing) seems to be unaffected. i use 8 channels of TDIF for my mixing busses.

-- sometimes when it is at maximum freakage the ADAT inputs also freak out (though they stop when i unplug the TDIFs). much of the time, though, the ADAT inputs are OK... the TDIF inputs are very rarely all OK, and that only lasts for a few minutes before they're back to pinning again.

do you have any clues what kind of hardware issue we'd be talking about here? i notice some posts on the Tascam DM24 forum that mention bad capacitors (accompanied by horror stories of trying to replace them). i'm a computer geek, but soldering has never been my forte...

thanks again for the reply.

[kkarney]

it looks like i've got a bad PSU on my DM24, so that (hopefully) is the source of my woes...