828mk3 internal trimpot?

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Discussion related to installation, configuration and use of MOTU hardware such as MIDI interfaces, audio interfaces, etc. for Mac OSX
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WesEdit
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828mk3 internal trimpot?

Post by WesEdit »

Hi everybody !

Yesterday my Motu 828 mk3 hybrid went in fire :oops: , so I opened it and seen a burnt capacitor in the power section... The stock one is a 33uf 400V, but someone told me that it isn't risky to replace it with a 47uf 350V (that I got atm) should I do it?

Also, I seen inside the soundcard a mysterious white trimpot. Does someone know its function?
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Phil O
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Re: 828mk3 internal trimpot?

Post by Phil O »

Simply replacing a damaged component is not necessarily the smart thing to do. One must ask themselves, "What caused the failure of said component in the first place?" Often times the cause of the damage (that you see) is elsewhere in the circuit. For example, if that's the filter cap in a simple rectifier circuit, I'd check the diodes before powering up with a new cap in place or you could fry that one as well. That's just one example. There are many other things that could have gone wrong. :?

I would never try to troubleshoot something like that without a detailed schematic.

Phil
DP 11.23, 2020 M1 Mac Mini [9,1] (16 Gig RAM), Mac Pro 3GHz 8 core [6,1] (16 Gig RAM), OS 14.3.1/11.6.2, Lynx Aurora (n) 8tb, MOTU 8pre-es, MOTU M6, MOTU 828, Apogee Rosetta 800, UAD-2 Satellite, a truckload of outboard gear and plug-ins, and a partridge in a pear tree.
WesEdit
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Joined: Fri Feb 05, 2016 7:00 am
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Re: 828mk3 internal trimpot?

Post by WesEdit »

Thanks for your answer, yea I don't know where the problem comes from, but I seen on internet people had the same issue with the same capacitor apparently they just changed it...
I finally replaced the 33uf 400V cap with a 47uf 350V and also an other cap which swelled a bit. It seems to work great at the moment. My 828 is a second hand, bought it 2 years ago and the previous owner had it since 3 years.

I tried to find a replacement card for power section, in vain.. However someone on a forum found a way to buy one. Any ideas where I can get that?

I don't think Imma call Motu cause no guarantee, and paying thousands euros for replacing caps (if it's only that)... meh :)
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terrybritton
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Re: 828mk3 internal trimpot?

Post by terrybritton »

Call MOTU and ask about their $99 replacement offer. Out-of-Warranty is what that is for. I had a second hand 828 mk3 hybrid they replaced for me, with a warranty on the replacement. Hard to beat!

Terry
Computer: Sweetwater CS400v7 Intel Core i7-10700K CPU @ 3.80GHz | 64Gigs RAM | Windows 11 Pro x64 |
MOTU 828 mk3 hybrid

DAWs & Live: MOTU Digital Performer 11.31 | Cantabile Performer 4
Keyboard Synths: Kawai K5000s, Korg Wavestation
Controllers: NI Komplete Kontrol S-88 Mk3 & S-49 Mk2; Maschine Mk3 & JAM;
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Tutorials: https://youtube.com/@CreatorsMediaTools
WesEdit
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Re: 828mk3 internal trimpot?

Post by WesEdit »

That sounds interesting thanks for the advice, I'll check this.

For that matter do you know about that trimpot inside? this is getting me curious :o
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terrybritton
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Re: 828mk3 internal trimpot?

Post by terrybritton »

WesEdit wrote:That sounds interesting thanks for the advice, I'll check this.

For that matter do you know about that trimpot inside? this is getting me curious :o
It may be a bias setting - see if anyone at MOTU support knows (call first).

I would not touch it without a schematic and test equipment. You cannot "guess at" bias settings and such, or go by listening.

Terry
Computer: Sweetwater CS400v7 Intel Core i7-10700K CPU @ 3.80GHz | 64Gigs RAM | Windows 11 Pro x64 |
MOTU 828 mk3 hybrid

DAWs & Live: MOTU Digital Performer 11.31 | Cantabile Performer 4
Keyboard Synths: Kawai K5000s, Korg Wavestation
Controllers: NI Komplete Kontrol S-88 Mk3 & S-49 Mk2; Maschine Mk3 & JAM;
Akai MPK249 & 225, Alesis QX49, Behringer BCF2000 & FCB1010
Rack Modules: Ensoniq ESQm, Yamaha TX81Z, Wavestation SR

Tutorials: https://youtube.com/@CreatorsMediaTools
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