Is this a bad capacitor? RME Interface

[Darcy]

Hi everyone,

Would really appreciate anyone's input - music producer here with basic understanding in electronics. Would love to fix this myself if this is an easy one, would like to save the money for other things in life!

I have an RME 802 with 4 preamps at the front. When I turn on phantom for the 3rd one, I get a massive peak on the vu meter that slowly falls - see attachment. Does the same in the other phase direction when I turn it off. What does this look like to you? Is this the 48v DC blocking capacitor gone bad? Hoping it's an easy fix!

Thanks,

Darcy

P.S love this community! longtime lurker

 

[cyrano]

Looks like the cap is leaky, or one of the 6k8 resistors is shorted. Open the 802 and look at the caps near the mic input. If the one on channel 4 is bulging, it's bad. Has the 802 been in a hot rack?

It's easy to diagnose, maybe not so easy to fix. Unless you have experience soldering?

It's a multi-layer board with fine traces in there. No chance in finding a good tech with the right equipment?

I've stopped doing repair myself, because my eyes and hands no longer work as good as they used to. Besides, i'm only an amateur and doing SMD repairs would need an investment of around 1000€ (USB Microscope, soldering station, vacuum sucker... )

Since I found a very good tech literally around the corner, I'm not repairing anything complicated. Just cables and mics.

 

[Darcy]

Hi cyrano, thanks very much for taking the time to respond. Got it. I’ll open it up once I can and see if anything is bulging.

Yes, it has spent a bit of time in a hot rack, I also remember someone accidentally hot plugging it with phantom on?

And I don’t know of any techs in LA (anyways knows?) for this specific job, I called up the RME rep and they told me to send it across the country, which I’m a little hesitant to do if I can fix for $1 in parts. Maybe I can ask around and see if anyone knows one. It is LA after all.

Thanks again, if anyone has my more input that would be greatly appreciated

 

[cyrano]

I've "hot-plugged" mine a million times. No problem. I've seen however a few people who succeeded in plugging in the FW plug upside down. Immediate damage.

I've also seen at least two FW cards that supplied more than the allowed 30 VDC, resulting in slow death.

RME replaces either the PSU board (which is available separately) and/or the entire ADDA board, incl. plugs. It's a solid way of repairing, but not cheap. That is, for the FF800. I have no experience with the 802, I just assume it's more or less the same topology. The FF400 has just one board, as there isn't a built-in psu.

The job is simple for those who have the experience and a professional desoldering station. I did my first FF400 myself, without a desoldering station. Since then, I found an excellent tech just right around the corner, so I don't DIY it anymore. He's got a FF400 and a FF800 on the table atm. The 800 has ripped out FW ports (all of them) and the 400 simply needs a recap.

I don't know any techs in LA, but I'm sure someone else does.

 

[fragletrollet]

I changed some electrolytics on the psu-board on a FF800 some years back. The metering was going totally crazy, and would not connect to the computer + harsh digital noise. No real troubleshooting (wouldn't really know where to start, as the symptoms were so "all over the place" and hard to pinpoint. thought it was something wrong on the digital side), other than seeing that alot of people seemed to have problems with those exact caps (crappy psu I guess) ; was surprising to see it go from total havoc to completely well behaved by just switching out those few caps. My confidence has never been the same... ;=p

 

[cyrano]

The FF800's PSU is not made by RME. It's a fairly standard switching PSU. The only non-standard thing is it also supplies 48V for phantom power. You can get a new one from RME for a fairly moderate price. Of course, you can also recap it yourself.

We used to be a MOTU shop. Way back then, the local importer offered a fixed fee exchange repair. Fast and no surprises. When they stopped doing this, we started to look for alternatives, after a few hefty repair bills. There was already a FF400 in use and the tech who used it, liked it a lot. Since, we've bought an entire fleet (well, almost) of FF400s, a few FF800s and one Digiface USB.

When I compare repairability, the MOTUs aren't bad. The repair tech told me the failures are diverse. I like how these are built, but fault finding takes a lot more time. The RMEs seem to fail on two points: connectors, especially the FW connectors, and caps. Since these are easy and cheap to replace, we settled for RME. Caps only fail after spending ten years in a hot rack, or twenty years in a cool place. That's long enough for me.

When it comes to cost, RME beats MOTU, because they keep on supplying driver updates, even for very old stuff. MOTU doesn't, so they need to be replaced because of computer OS updates. And these are sometime needed because all software evolves.

 

[fragletrollet]

My Motu Midi XT has some of the worst software I've used. Ancient, cumbersome, unstable, very un-customizable and inflexible. But most importantly, unreliable.

If there is one thing that comes to mind when thinking about RME; it is that they have some of the most reliable, stable drivers and software I've ever used. I've used tons of different USB (and firewire, god forbid) interfaces over the years, and always felt scared before gigs that my interface/computer combo would hiccup on stage, or worse, crash altogether. My Babyface pro has never let me down, not even once. Not a super-fan of TotalMix (I'm so used to the SSL MX4 system I have at home, with completely customizable channel-strips that follow typical analog signal flow) but damn is it stable.

 

[cyrano]

I used to hate TotalMix, until I had to RTFM. Now, I'm a fan.

 

[Whoops]

I changed some electrolytics on the psu-board on a FF800 some years back.

In the FF800 PSU failling due to bad Lytic caps is quite common, most already had that problem or are having it at the moment. Recaping the PSU with new 105 degrees Lytic caps completely solves the problem
Replacing the complete PSU is expensive, changing the Lytic caps, recapping, is cheap and easy.

I don't think the same problem happens with the newer 802 unit,
I never seen until the present a 802 with a failled PSU, well but it's also a much newer unit...

 

[cyrano]

Depends on what you call expensive. 85€ for a small switched PSU isn't cheap, but it isn't really expensive either. Part number: 6308X

It's too soon for the 802 to fail. They've only been out since 2014. Cap trouble generally appears after 10 years or more if the unit has lived in a hot rack and after 20 years if used in a cool spot with ample airflow. We only have one 800 (and that one is in for a recap as we speak), but I can tell from the dozen or so FF400s we have. The oldest ones have been recapped, later ones are still in use despite being over ten years old. The 400s don't live in a rack, but the 800 did.

We had the same problem with the MOTUs, except that a few of them also had other trouble.