Universal Audio 710 Schematics

Hi.
I have two UA 4-710D Units in for repair. They have a terrible hissing noise when phantom power is activated. I have tried to measure the phantom power rail, and it seems quiet enough. The hiss is not the same on all four channels.
Can any of you point me in the direction of the fault, or better yet provide the schematic /service manual for this unit?
Thanks in advance!
Best regards,
Christian

Have you contacted universal audio?

Yes, I wrote to them several weeks ago, but haven't got a reply yet, unfortunately.

Try calling them, it often helps with others, can't say for UA. Finding fault here would be hard.
I wounder how long device built with flet connectors lasts, this could cause problems here.
A few people mentioned problems with Molex connectors after a few years and i've seen burnt connections on Mate N Lok. Warm Audio is one example, i replaced several wires and soldered them directly. Can't remeber name the other connector which also isn't that durable. Interesting topic, more and more even simpler gear uses connections like this even for PSU with higher currents.

It's not the Molex that's the problem, but the quality of the specific connector.

I've been running mostly everything (bar mains) in Molex for >27years - never (ever!) had to repair a single one just yet.

But if you get poor match or poor quality, some half-made connection can quickly build up to a disaster even at modest current.

It's a problem if you try to save 0.01 cents on 1-cents-hardware - not an issue if you go with standard decent parts.

Jakob E.

HI Christian

Did you ever get this problem sorted?

I have exactly the same issue with a 4-710 D version... phantom switched on and NNNOOOIIISSSEEEE... 3rd time it has failed

Rob