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Motu 828-mkii power supply
Old 3rd July 2013
  #1
Lives for gear
 
Entrainer's Avatar
 
🎧 10 years
Motu 828-mkii power supply

I've got a MOTU 828-MKII that I use for sequencing my modular synths.
(control voltage because it's DC coupled)

The unit is shutting off after 5-10 minutes, just a complete power down.
I'd send it back to MOTU for "repair", but I've had the Black Lion Audio
convertor modifications done to the unit. Apparently, MOTU doesn't repair
the 828MKII you send in, they swap it for another refurbished one and put
yours on the shelf to be fixed at a later date. Either way, mine is
"unauthorized" and heretical due to BLA mods.

I had the BLA technician take a look, and they are nearly positive it's the
power supply. It's just old and needs to be replaced. But they don't
offer any service on the units themselves or have the parts.

Anyone have any recommendations or know any reputable techs with
access to those parts?

THX-
Old 3rd July 2013
  #2
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2N1305's Avatar
 
🎧 10 years
What are "those parts"? Being made, or at least designed in the USA, these should be common parts... 78xx, LMyy, diodes, transistors... etc.

so basically you had an unauthorized repair and MOTU will not warrant it?
Old 3rd July 2013 | Show parent
  #3
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Entrainer's Avatar
 
🎧 10 years
Quote:
Originally Posted by 2N1305 ➡️
What are "those parts"? Being made, or at least designed in the USA, these should be common parts... 78xx, LMyy, diodes, transistors... etc.

so basically you had an unauthorized repair and MOTU will not warrant it?
Well, it's out of warranty completely.

The "issue" is I had an upgrade done to the unit (BLA conversion upgrade).
If I send it to MOTU with $, they just swap it out for another refurb, so I'd
lose the custom upgrade. That's even if they'd accept it at all.

"Those parts" yeah, that's the question I don't know the answer to and
why I'm humbly asking for information or help. I'm going to unrack it and
take a look, but from what I've gathered, it's an internal power supply that
needs to be replaced.

I guess what I need to find out is if the power supply is custom MOTU
designed or a 3rd party all-in-one that is replaceable. And if the power supply
is custom designed by MOTU, do they sell the part to techs?
Old 4th July 2013 | Show parent
  #4
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2N1305's Avatar
 
🎧 10 years
Quote:
Originally Posted by Entrainer ➡️
Well, it's out of warranty completely.

The "issue" is I had an upgrade done to the unit (BLA conversion upgrade).
If I send it to MOTU with $, they just swap it out for another refurb, so I'd
lose the custom upgrade. That's even if they'd accept it at all.
I understand now.

Quote:
Originally Posted by Entrainer ➡️
"Those parts" yeah, that's the question I don't know the answer to and
why I'm humbly asking for information or help. I'm going to unrack it and
take a look, but from what I've gathered, it's an internal power supply that
needs to be replaced.

I guess what I need to find out is if the power supply is custom MOTU
designed or a 3rd party all-in-one that is replaceable. And if the power supply
is custom designed by MOTU, do they sell the part to techs?
Well, you'd have to ask MOTU whether they sell to particulars. But you might not need to do that, at least not until you've discovered what the the problem is, and to do this, as you pointed out, you must take it apart.

I for one, believe this can be very simple because power supplies usually are pretty simple, unless they're switching, and I don't think the 828 would have had an internal switching supply. Come to think of it, there is a 120V IEC plug that goes right in the back if the unit?
Old 4th July 2013
  #5
Lives for gear
 
2N1305's Avatar
 
🎧 10 years
By the way, I totally dig your avatar, "Dude"...

Well, you know, that's just like, your opinion, man.
Old 4th July 2013
  #6
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LeeYoo's Avatar
 
🎧 10 years
Could be this.
MOTUNATION • View topic - For those with dead 828MK IIs
Reflow the LM1117 with fresh solder and try, before you replace.
Leo..
Old 6th July 2013 | Show parent
  #7
Lives for gear
 
Entrainer's Avatar
 
🎧 10 years
Quote:
Originally Posted by 2N1305 ➡️
Come to think of it, there is a 120V IEC plug that goes right in the back if the unit?
Yep. I tried to open it up and got stuck without the proper size allen wrench.
I had all the larger and smaller ones but not the ONE I needed.
I'll have to go buy a new one.

However, I did find this image online of the 828 MKII insides



Quote:
Originally Posted by 2N1305 ➡️
By the way, I totally dig your avatar, "Dude"...
Thanks!

Quote:
Originally Posted by LeeYoo ➡️
Could be this.
MOTUNATION • View topic - For those with dead 828MK IIs
Reflow the LM1117 with fresh solder and try, before you replace.
Leo..
That looks like it could be related, thanks.
Old 6th July 2013
  #8
Lives for gear
 
🎧 15 years
Hi
How long do you have to wait before it will come back on again?
It could be a supply regulator overheating which automatically shut down until cool.
Loosen the lid and power it until it shuts off then UNPLUG THE MAINS CABLE and quickly feel for hot parts, LM317/117 regulators or typically anything in the supply department.
There appear to be 2 'regulators' (or could simply be transistors I can't see from the picture) that have no heatsink. If this is the case in your unit I would be suspicious of them. There appears to be a rectangular 'pad' on the circuit board where a surface mount version of the device that is currently 'standing' may be intended to be 'soldered' so that the board copper acts as a heatsink.
It may be the BLA 'mod' actually pulls a little more current than the original unit which itself may be 'marginal'.
You could also try running it lid off (fingers out) with a fan blowing it cool and see if it stays on.
Happy hunting.
Matt S
Old 6th July 2013
  #9
Lives for gear
 
LeeYoo's Avatar
 
🎧 10 years
The regulators are just above the left hand transformer.
The circuit board is discoloured there, indicating too much heat over time.
I would say this is a desigh flaw (or inbuilt obsolescence).
Reflowing that hot part (flat on the board) with fresh solder might fix it.
Check for bulging caps in that area as well...
If it was my unit, I would solder a small strip of copper or something to the top tab of the hot part and and bend it up, to give proper cooling.
Leo..

P.S. Opening this unit is very easy. Two screws on the top lid....
Somewhere in this post you can find a detailed document of how to open the unit further.
MOTU 828 mkII USB crackle
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