Yeah. The two reservoir caps were rotated 180 º between Rev. 1.0 and 2.0 of the board to accommodate the pinout of the 6-pin Molex output connector on Rev. 2.0.
My money is on a solder bridge or a sketchy connection to the power transformer. Either a loose connection or a wrong connection. It could also be a weak solder joint, though I don't see an obvious suspect in the photos.
Tom
My money is on a solder bridge or a sketchy connection to the power transformer. Either a loose connection or a wrong connection. It could also be a weak solder joint, though I don't see an obvious suspect in the photos.
Tom
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Thanks for your input Tom, I will check solder carefully later.
The transformer connection is the same on V1 or V2? AC/0/0/AC?
Thanks
There's just enough room, you can see it marked on the board, even with the green terminal blocks in place. Peek down to see the board between the heatsink and the terminals.
Also, the instructions in the build manual that comes with the board have lots of detail about this.
Bracket: Board to heatsink ???
Hello,
I noticed from one of the links on Neurochrome website, to a slideshow of Poisedon's Voice build.
He uses a small "L Bracket" to mount the Mod-86 Board to heat-sink.
Does anyone happen to know where to find such a bracket? Is it a part available at Mouser for example?
My next Mod86 amp will be complete in the next couple of weeks, and I want to use that method instead of standoffs, at least on the heatsink side of the board. I think that lining everything up, drilling, tapping, etc before I solder LM3886 chip in place will be easier with the brackets.
(The attached photo is from Poseidon’s Voice – Neurochrome Modulus-86 Rev. 2.1 Build. Poseidons Voice Modulus 86 Slideshow by nycavsr2000 | Photobucket)
Hello,
I noticed from one of the links on Neurochrome website, to a slideshow of Poisedon's Voice build.
He uses a small "L Bracket" to mount the Mod-86 Board to heat-sink.
Does anyone happen to know where to find such a bracket? Is it a part available at Mouser for example?
My next Mod86 amp will be complete in the next couple of weeks, and I want to use that method instead of standoffs, at least on the heatsink side of the board. I think that lining everything up, drilling, tapping, etc before I solder LM3886 chip in place will be easier with the brackets.
(The attached photo is from Poseidon’s Voice – Neurochrome Modulus-86 Rev. 2.1 Build. Poseidons Voice Modulus 86 Slideshow by nycavsr2000 | Photobucket)
Attachments
The Keystone 4332 won't work with the MOD86. First off, it takes a #6 screw and the holes in the MOD86 board are sized for #4 (or M3).
The brackets shown above are not the Keystone 4332. I don't know what they are. Anand?
For the MOD86, you'll want brackets for use with M3/#4 screws. The distance from the mounting hole centre to the heat sink surface should be 0.219" (5.56 mm).
Tom
The brackets shown above are not the Keystone 4332. I don't know what they are. Anand?
For the MOD86, you'll want brackets for use with M3/#4 screws. The distance from the mounting hole centre to the heat sink surface should be 0.219" (5.56 mm).
Tom
I don't remember the part number but you are correct, the L-bracket I used was made for 4-40 screws.
There are a few listed here:
https://www.digikey.com/products/en/hardware-fasteners-accessories/mounting-brackets/574
https://www.sparkfun.com/products/10228
Somebody will have to double check on the measurements.
Best,
Anand.
There are a few listed here:
https://www.digikey.com/products/en/hardware-fasteners-accessories/mounting-brackets/574
https://www.sparkfun.com/products/10228
Somebody will have to double check on the measurements.
Best,
Anand.
I'll let you know how I make out with the brackets. I'm trying the keystone 521-612 listed above. I noticed the distance from center of hole to the bend is only 5.16mm, and I think it should be 5.56mm (or whatever Tom said above)
Half a millimeter isn't much, and it may work as is, so long as I'm able to get the board parallel and screw all the way flush to the bracket. I might need to open the hole a little more to get the room I need, in which case I'll need a little nut as well. Brackets will be here by next weekend.
On the up-side, I finally decided to get a drill press. I don't plan that it will help with the brackets at all, but I know all the other holes in the chassis and heatsink will be square or plumb.. whatever you call it.
I'm kind of excited. Spent some time last night with a carpenters-square, I've got the deck exactly 90 degrees relation to drill bit.
I plan that when I'm ready to tap holes in the aluminum, I'll put my tap in the drill-press chuck, and just turn the chuck by hand. Might help to keep everything square.
Half a millimeter isn't much, and it may work as is, so long as I'm able to get the board parallel and screw all the way flush to the bracket. I might need to open the hole a little more to get the room I need, in which case I'll need a little nut as well. Brackets will be here by next weekend.
On the up-side, I finally decided to get a drill press. I don't plan that it will help with the brackets at all, but I know all the other holes in the chassis and heatsink will be square or plumb.. whatever you call it.
I'm kind of excited. Spent some time last night with a carpenters-square, I've got the deck exactly 90 degrees relation to drill bit.
I plan that when I'm ready to tap holes in the aluminum, I'll put my tap in the drill-press chuck, and just turn the chuck by hand. Might help to keep everything square.
The holes in the MOD86 board are 0.200" (5.08 mm) from the board edge. The LM3886 protrudes 0.019" (~0.5 mm) past the board edge. There's some wiggle room in the holes for the LM3886, so 5.16 mm will probably work. The mounting holes in the board are 0.130" (3.3 mm) in diameter so you'll have a bit of wiggle room there as well with an M3 and especially with a #4-40.
I use a Jet JDP-12 drill press. Love it! I replaced the cheap handles with round ones from McMaster-Carr. I would not use a drill press for tapping, though. You won't get the vertical feed right and the return spring tension tends to be too high. I tap everything by hand using a tapping block. The block helps keeping the tap vertical.
Tom
I use a Jet JDP-12 drill press. Love it! I replaced the cheap handles with round ones from McMaster-Carr. I would not use a drill press for tapping, though. You won't get the vertical feed right and the return spring tension tends to be too high. I tap everything by hand using a tapping block. The block helps keeping the tap vertical.
Tom
Yeah, jets are the best!
I didn't think about the spring tension,.. that would be a problem
The pilot holes will be right though, in my mind that part is pretty important. I have a little jig thing, like a steel cylinder sleeve in a plastic block. It worked for me on my last Mod86 build,.. kind of a pain to use though with a hand drill for pilot holes.
Will I do the tap part by hand.
I didn't think about the spring tension,.. that would be a problem
The pilot holes will be right though, in my mind that part is pretty important. I have a little jig thing, like a steel cylinder sleeve in a plastic block. It worked for me on my last Mod86 build,.. kind of a pain to use though with a hand drill for pilot holes.
Will I do the tap part by hand.
Tom, guys,
I got following case:
1. ak4490 -> 2xLL1684 (audio output transformers) diff output -> XLR/XLR cable -> Modulus-86. So summing is done by THAT1200 receiver.
2. ak4490 -> 2xLL1684 SE output -> RCA/XLR pseudo diff cable -> Modulus-86. So summing is done by audio transformers at DAC output.
Case 1 gives me brrruming/hum at speakers.
Case 2 gives me NO brrruming/hum.
Do you have any idea why is so? What could cause that brumming in case of fully differential connection?
I got following case:
1. ak4490 -> 2xLL1684 (audio output transformers) diff output -> XLR/XLR cable -> Modulus-86. So summing is done by THAT1200 receiver.
2. ak4490 -> 2xLL1684 SE output -> RCA/XLR pseudo diff cable -> Modulus-86. So summing is done by audio transformers at DAC output.
Case 1 gives me brrruming/hum at speakers.
Case 2 gives me NO brrruming/hum.
Do you have any idea why is so? What could cause that brumming in case of fully differential connection?
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Sorry if I'm getting off topic of Mod86, but I learn so much by participating; and I have a quick question.
Is AK4490 DAC really made to send a Differential Output direct from the DAC to outside the DAC chassis (via audio transformer)?
I realize the AK4490 Chip itself outputs a differential signal, but I thought it was meant to be converted to single-ended inside of the DAC chassis, as part of its output stage because of a certain requirement for summing the signal which involves a low pass filter. I would expect the builder would have a couple of different summing LPF and switch between them depending on if the mode was PCM or DSD
Maybe I misunderstand,... I've a lot to learn
Case 1 probably hums because the common-mode voltage on the input of the THAT1200 is not defined. I suggest tying the centre tap of the LL1684 secondary to ground. The best place to do that is at Pin 1 of the input connector to the MOD86.
Tom
Oh boy. Yesterday the parts from Mouser arrived for my 2 x 286s and I was pretty intimidated by the tiny size of some of these items as this is my first SMD project. Then I thought what the heck, got my SMD practice board out, which was recommended earlier in this thread and started soldering. To my surprise, I even got the first SMD soldered in nicely and even the smallest one, by just following the YouTube vids on SMD. Big relief, as this gave me the confidence back to build the 286 as soon as they arrive.
Question: Is there a best practice strategy when populating these 286s? Do you go row by row or do you solder all the items of one type (e.g. x Ohm resistors) before moving to the next type (e.g. y Ohm resistors?
Thx
SH
Question: Is there a best practice strategy when populating these 286s? Do you go row by row or do you solder all the items of one type (e.g. x Ohm resistors) before moving to the next type (e.g. y Ohm resistors?
Thx
SH
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The answer is on page 21 of Tom's Design Document that he e-mails when you've purchased.
Thanks I know page 21. What I meant was; e.g. of all the resistors do I do the 1ks first then do the 2ks (dummy values) and so on or do I go R1,R2 etc (