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Mini^3 DIY Tips

post #1 of 20
10/16/09 at 10:23am
Thread Starter 
As we say in the South, I'm "fixing to" begin building a Mini^3. I have almost everything in place, I've read tons of threads and other electronic information sites and I've gotten some specific advice from |joker|.

I wanted to ask the broader community of head-fi for tips, tricks and/or advice from everyone's experience about doing this project. I don't care if it's specific to the Mini^3 or building electronics in general. If you have learned something that should be done, or shouldn't be done, please let me know.

thanks,
buff
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post #2 of 20
10/16/09 at 10:29am
DO NOT ATTEMPT to plug in the 9V battery backwards. That seems to be a common problem.
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post #3 of 20
10/16/09 at 10:56am
rule number 1 lots of liquid flux
rule number 2 lots of alcohol to clean with
rule number 3 do your opamps first, fully fluxed up, with a well tip or broad tip, at the lowest setting, id say around 300c since some pins are grounded
rule number 4 Set your gain resistors like a half inch above your board for easy removal should you guess wrong.
rule number 5 mount your beads 1/4" above the pcb or what ever they say.
rule number 6 Mount your volume pot last after you have throughly cleaned the pcb before hand
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post #4 of 20
10/16/09 at 11:05am
I do not agree with the above poster about Rule 4 with the gain resistors. The excess lead in the feedback loop can cause issues. The opamps used in the mini3 are high-bandwidth and that excess lead could cause to oscillation. Not hard to cut out a resistor if you need to even if it is flush to the board.
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post #5 of 20
10/16/09 at 11:10am
do it step by step. Many builders here apparently solder/populate too quickly and impatiently.
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post #6 of 20
10/16/09 at 11:33am
When you solder the capacitors in (the large electrolytic ones) and the diodes, check that the fit inside the case you're using. I remember having to bend one of the capacitors so I left an extra 1/4" lead between the board and the bottom of the capacitor so I could bend it and get it inside the hammond case.
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post #7 of 20
10/16/09 at 11:33am
I'm guilty of it , but since I have been very confident in my soldering I tend to rush.

When soldering the pot, don't forget the outer two pins. The Mini³ won't turn on otherwise. And be sure the pins sticking out the bottom (the jacks, battery clips, screw, etc) don't scratch the case's floor. Trim them with whatever you use to cut resistor leads.

Also, if possible try not to do it in one sitting; take rests every hour or so. I finished my y1/y2 in seven hours, and boy was I angry, frustrated, drowsy, disoriented, etc. One voltage regulator replacement later and an hour of defluxing and I have a working y2.
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post #8 of 20
10/16/09 at 11:34am
Quote:
Originally Posted by m1abrams View Post
I do not agree with the above poster about Rule 4 with the gain resistors. The excess lead in the feedback loop can cause issues. The opamps used in the mini3 are high-bandwidth and that excess lead could cause to oscillation. Not hard to cut out a resistor if you need to even if it is flush to the board.
I put them down to board level once i like the gain. They wouldnt fit into the case air wired like that
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post #9 of 20
10/16/09 at 11:36am
Quote:
Originally Posted by nightanole View Post
I put them down to board level once i like the gain. They wouldnt fit into the case air wired like that
I do not understand why bothering with air wiring? Is it to save the resistor if you need to remove it? If that is the case I do not feel an 8cent part is really worth that level of effort.
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post #10 of 20
10/16/09 at 11:57am
I find it easier to remove and not damage the board if i have them alittle above the board. i could care less about the resistor, but id hate to lift a pad trying to remove a kinked lead.
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post #11 of 20
10/16/09 at 12:00pm
Quote:
Originally Posted by nightanole View Post
I find it easier to remove and not damage the board if i have them alittle above the board. i could care less about the resistor, but id hate to lift a pad trying to remove a kinked lead.
Ah - another tip. Clip the lead as close to the pad as possible. Then use solder wick to get most of the solder up and you can heat the lead in the hole and push it through with a stainless dental pick. Much better for the pads then trying to pull the lead through.
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post #12 of 20
10/16/09 at 12:39pm
1. Take the battery you have and slide in between the pcb and top of case. If it fits you're a golden boy. The rest of us have to remove the wrapper and grind the battery down slightly along the top edge on both sides.
2. Use a Dremel and grind down the battery contacts.
3. Mount the battery contacts first (OBSERVE CORRECT POLARITY) with the battery in place as a jig. Make sure the battery sits flat on the pcb. Use a clamp to hold it in place while soldering. Test before moving on.
3. Remove the battery and follow the mini3 guidelines for the rest making extra sure the tallest caps are seated all the way down to the pcb. Test before moving on. Allow some extra play in the C5's and L1G to bend sideways. They will hit the sides of the case and must have some give. Test before moving on.
4. Make sure that none of the leads underneath make contact with the case before sliding the pcb into it with the battery installed
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post #13 of 20
10/16/09 at 12:51pm
Sorry in my earlier post I said diodes, I meant the inductors because one of them can jam against the rails of the hammond case.
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post #14 of 20
10/16/09 at 6:00pm
i did mine in about 3 hours one night, i was jet lagged and could not sleep

go slowly

think about what you are doing

if you clean only one thing, clean then flux carefully off the chips. i had waaaay too much offset due to some not quite clean legs

think about what you are doing

go slowly
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post #15 of 20
10/16/09 at 10:57pm
Man im kinda jealous of all you 3 hour guys for the mini3 and bantam. I normally milk these things for 3 weeks. Eh tonight ill kick back and pop in all the resistors, ill solder them tomarrow...
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