Motu 896 original repair

[hexdiy]

Hey dear people,

 

as well as being a colleage of yours ( stage manager, LD, Board-op, video tech, sound operator, best boy electrician, you name it - most of us on the job around here are general practitioners), I am also a bit of an electronics repair hobbyist and vintage Apple Mac enthusiast from Flanders, Belgium. Have been reading over your shoulder for quite a few years now. Great forum, as I always tell our interns...

 

This week I acquired an old Motu 896 ( 1st gen 6-pin dual FireWire 400) very cheaply. The poor old bastard was not performing at all anymore under Windows with its former owner. So its former owner basically ditched the unit.

On my MacBook Pro , however, I have installed a genuine arsenal of all kinds of Motu drivers and software. Lo and behold:

 

This particular Motu 896 gets recognised upon startup, and seems to behave excellently (iTunes playback, Youtube playback, Spotify, Bandcamp and SoundCloud streaming as a signal source on input 1&2) for an hour or so. Afterwards, it drops out, simply freezes. Seems like it looses contact with the FireWire host computer. MOTU Audio Setup seems to confirm this.

After that interval, a hard reboot with host computer, signal source and FireWire connection still hot will get the unit online again, but this interval gets shorter & shorter until a reboot will no longer get it online.

The unit, however, does not seem overly hot to the touch.

My suspicion is that the Motu power supply has an extravagantly high ripple on the 5V line due to an ageing main capacitor that worsens with the PSU gradually heating up (haven't checked this yet with a scope, btw).

Any thoughts on this? Maybe even some schematics of this particular power supply?

My alternative suspicion rests on the resilience of the 6 physical FW 400 contacts within the Motu chassis. Some internet sources seem to suggest this much. Visual inspection with a magnifying glass seems to point in that direction also.

No dirt, no oxide, but the spring- load seems to have gone out of the contacts; in other words: the contacts seem poorly thin.

Any similar experiences, maybe?

Many thanks for your comments!