MOTU Traveler Mic I/P schematic/layout?

[ricardo]

Does anyone have a schematic or service info for a MOTU Traveler microphone input stage?

I bought one in 2007 and almost immediately, 2, then 3 channels started to have loadsa noise. I sent it back to MOTU from Oz and got it back after 3 mths. Exactly 12mths after that, 1 channel went noisy the same way.

The Oz distributors told me there was a large batch with the same problem. Big backlog of main PCBs to be changed for exactly this fault.

But my experience suggests they haven't sorted the problem out.

MOTU themselves don't give out any info and deny there is any problem. It is possible the Traveler was designed outside MOTU and they have no one in house who understands the problem.

From what I can see, it's likely to be something simple like leaky P48V caps or protection diodes. But I need at least a schematic and preferably a layout before I start digging. SMD and multi-layer difficult for my old eyes.

It's a pity as, when its working, the Traveler is superb. I would have been proud if my Jurassic Calrec efforts had the same performance.

It seems to use a custom programmable TI chip, maybe based on PGA2500.

Excuse me if this is the wrong place to post.

[mediatechnology]

From what I can see, it's likely to be something simple like leaky P48V caps or protection diodes.

Does it do it with phantom off? The P48V caps would be a good place to look.

Did they use 1N4148 (in SMT) protection diodes? That would also be a good condidate. Depending on where they placed the diodes it could do it with phantom on or off.

[ricardo]

The noise is there with or w/o P48V.

My problem is identifying the protection diodes & i/p caps.

I would replace them with 1n4004 & nice Al. electrolytics.

Need a BIG magnifying glass I think.

[mediatechnology]

Send us a pic?

The TI app for the PGA2500 IIRC showed whimpy protection diodes to the rails which do become leaky (if not shorted or ohmic) after faults. MOTU may have followed the app right out of the book.