828 MkII Humming!

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Discussion related to installation, configuration and use of MOTU hardware such as MIDI interfaces, audio interfaces, etc. for Mac OSX
tombola
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Re: 828 MkII Humming!

Post by tombola »

Wanted to re-open this old post, because I found a fix for Motu 828 Mk 2 physical transformer hum that I hadn't seen anywhere else.

I had a unit that worked OK for many years, then suddenly developed an annoying physical hum. OK if it was in a rack somewhere, but very annoying when I moved it under my iMac, right 18" from my head.

I opened the unit, tightened/loosened the transformer screws, tried to squeeze glue into the transformers etc, nothing worked.

Then I spotted that C205 - a capacitor near the transformers - looked wonky and appeared to have leaked some fluid. It's a 330uf 63v Electrolytic capacitor.

I replaced that capacitor (it was pretty fiddly to desolder the old one, I ended up soldering the ground wire directly to the PCB trace) and immediately the hum is dramatically reduced.

[YouTube]http://www.youtube.com/watch?v=zVey-8ROmZY[/YouTube]
yapweiliang
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Re: 828 MkII Humming!

Post by yapweiliang »

Thank you for that - I will try one of these days. Can I ask - when you opened it - did it seem the hum was from capacitor or from transformer?

(or maybe I should get another one - now the backlight for the LCD display is gone as well)
tombola
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Re: 828 MkII Humming!

Post by tombola »

The buzz seemed to be from the transformer.
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bogmusic
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Re: 828 MkII Humming!

Post by bogmusic »

I just de-soldered and re-soldered the transformer in my motu 828 mk2. No noise at all now. None. It buzzed so much previously that it just put me off using it at all.

All I did was to pull the transformer away from the main board while de-soldering and resoldering the joints. It now sits about 1mm above the board and I repeat - there is no noise at all!

I dont know if re-soldering capacitor c205 was anything to do with it but one of the joints looked a bit dry so I re-soldered it anyway.

I am going to try the same thing on my 1224 next (slight buzz but nowhere near as bad as the 828 was.
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Re: 828 MkII Humming!

Post by mikehalloran »

My 828mkII sits approximately 18 inches from my face. Until reading this thread, I never noticed a hum or a buzz. After reading this thread I stood up and put my ear against the top of the case.

There is a slight buzz.
Sonufagun, mine does, too.

I checked my other rack gear. The MTP AV does not. Almost everything else does.

My 828mkII is the most noticeable rack mount as I can detect it from about 10" away if I know what to listen for. I do now...

Not as loud as my Mac or HDs, however.
DP 11.31; 828mkII FW, micro lite, M4, MTP/AV USB Firmware 2.0.1
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Re: 828 MkII Humming!

Post by dosuna11 »

Got my 828MK2 this summer back from MOTU repaired for bad input. Finally sat down tonight to do some work and the thing buzzes like crazy. Do they not check this stuff out when it leaves the repair facility? I have a serious project coming and more down time! I should have checked this out when I got it back. I am gong to try the fixes. :banghead: Any other ideas?
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Re: 828 MkII Humming!

Post by dosuna11 »

Started on the fix. Thanks MOTU for the stripped screw in the chassis.
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Re: 828 MkII Humming!

Post by dosuna11 »

Off to get a screw extractor. :surrender:
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Re: 828 MkII Humming! Fixed

Post by dosuna11 »

All is quiet now. Took the unit to where I teach and the electronics repairman and I took it apart. We had to drill out the stripped screw. His remark was who the... torqued these screws down. Upon opening it was apparent what was buzzing. The shielding around one of the transformers was vibrating. The fix was a plastic toothpick inserted between the windings and the shield. Worked like charm. It is 12 inches from my head and I can not her it. Here is a link to a pic of the fix.
http://www.davidosuna.com/html&swf/828fix.html
iMac 2.7Ghz quadcore i5 16 gig RAM DP 7.24 OS 10.6.8, iMac G5 2.1GHz 2.5 gig Ram DP 5.13 OS 10.4.11 MOTU 828 MK2, East West Platinum Plus, Miroslav Philharmonic, Komplete 5, Kontakt 2 Garritan Big Band, Mr Sax T, The Trumpet, DrumCore, Trilogy and Trillian, Ivory, MachFive, Ethno Instrument, Reason 4, SampleTank 2 Sampletron, Samplemoog, Melodyne Editor, Nomad plugins, Vintage Warmer, Ozone 4, Amplitube Jimi, Xgear and AmpegSVX.
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yapweiliang
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Re: 828 MkII Humming!

Post by yapweiliang »

Thank you for the picture. My unit's buzzing more subtle nevertheless definitely audible. Will try toothpick next time I open it up.
buenavista
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Re: 828 MkII Humming!

Post by buenavista »

Old thread but what the heck . . . I've had my 828 mkii for over a decade. It's always had a slight tolerable buzz/humm, but a few days ago it suddenly became much worse and intolerable. Great to see so many have had some success in curing the problem. I'll probably dig into it this weekend to see if I can fix it.
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Re: 828 MkII Humming!

Post by smcelyea »

buenavista wrote:Old thread but what the heck . . . I've had my 828 mkii for over a decade. It's always had a slight tolerable buzz/humm, but a few days ago it suddenly became much worse and intolerable. Great to see so many have had some success in curing the problem. I'll probably dig into it this weekend to see if I can fix it.


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smcelyea
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Re: 828 MkII Humming!

Post by smcelyea »

Apparently it needs the words .


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stubbsonic
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Re: 828 MkII Humming!

Post by stubbsonic »

I used google and found this at the top of the heap.

http://cdn-data.motu.com/manuals/firewi ... al_Mac.pdf
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buenavista
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Re: 828 MkII Humming!

Post by buenavista »

tombola wrote:Wanted to re-open this old post, because I found a fix for Motu 828 Mk 2 physical transformer hum that I hadn't seen anywhere else.

I had a unit that worked OK for many years, then suddenly developed an annoying physical hum. OK if it was in a rack somewhere, but very annoying when I moved it under my iMac, right 18" from my head.

I opened the unit, tightened/loosened the transformer screws, tried to squeeze glue into the transformers etc, nothing worked.

Then I spotted that C205 - a capacitor near the transformers - looked wonky and appeared to have leaked some fluid. It's a 330uf 63v Electrolytic capacitor.

I replaced that capacitor (it was pretty fiddly to desolder the old one, I ended up soldering the ground wire directly to the PCB trace) and immediately the hum is dramatically reduced.

[YouTube]http://www.youtube.com/watch?v=zVey-8ROmZY[/YouTube]
I finally dug into my 828mkii. I had three swollen caps, including c205 that tombola mentions. Replaced them all, and got the same results as tombola--dramatically reduced humm. Before the replacement the humm was intolerable, now it is hardly noticeable. I actually just ordered an an original traveler (bus powered or wal-wart)to replace the 828. Hoping for the same sound with absolutely zero noise.
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