Bonsai’s X-Altra MC/MM Phono Preamp

The only thing I miss is the exact location of the components on the motherboard. There is a label on the board, but it is very, very small. I would welcome the marking of the components on the board in pdf format.
Thank you.
Jardalukas,
It is very difficult for me to generate a decent overlay because the board was designed on Traxmaker. I tried exporting the overlay to DXF but reading it back gives mixed results with online viewers. So I have to ask you to go by the silk screen on the PCB which is what the other 60 builders have done. The overlay text height is 0.7mm. Apologies for any inconvenience.

(note, all my new boards are on Traxmaker!)
 
I believe that Traxmaker is a Windows program. You make be able to print to a virtual printer such as one named "Microsoft Print to PDF" or one named "Save as PDF." The choice of printers may be in a pull-down menu called "Destination" on the File/Print menu. Printing to PDF is a nifty trick and should be available in a Windows environment...

-Jon
 
Quick update: Manuel has remarked the SPST Mouser alternative to the RS part in the BOM is an M12 bushing switch (so close to 1/2") vs the RS part which is 1/4" (6.34mm) bushing. The BOM is now updated to Sept 2024 and a 1/4" bushing alternative to to RS part number called up.

BOM will be up in the first post in about 5 minutes.
 
Jardalukas,
It is very difficult for me to generate a decent overlay because the board was designed on Traxmaker. I tried exporting the overlay to DXF but reading it back gives mixed results with online viewers. So I have to ask you to go by the silk screen on the PCB which is what the other 60 builders have done. The overlay text height is 0.7mm. Apologies for any inconvenience.

(note, all my new boards are on Traxmaker!)
That should read ‘none of my new boards . . . ‘
 
... The BOM is now updated to Sept 2024 and a 1/4" bushing alternative to to RS part number called up...
It looks like something happened to that Mouser number for the SPST got messed up (it just says "2" in the Notes column).

What does item 32 refer to (Filter T/O -- SIP3 -- J1, J2)?

You should also add Mouser part# 164-4200 as an alternative to the RS binding post.

Would one of these work for the 12-position DIPs?

-Jon
 
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I've ordered another batch of boards. They will be in stock in about 2 weeks after which I will ship them out. Thanks for your patience

(If I have counted correctly about 70 of these have been built and one builder here in the UK did 3 or 4 - every time he loaned his out to a friend, he never got it back!)
 
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I ordered this one yesterday, it should fit, but I will confirm it once it arrives.

Nkk spst toggle switch 633-M2011S3A1W01

Regarding the rest of the BOM there are a lot of differences in quantities between the board and the BOM. Some stuff is missing and other is more than needed.

For anyone ordering from mouser, I filled an RMA for the wrong switch and the extra parts I had and they gave me a refund without the need to return the parts. I guess it’s cheaper for them this way.
 
I now have all parts (including PCBs and chassis) ordered.

For what it's worth, I will go with soldering paste and a hot air gun for the SMD soldering. I have only done one project with just a few SMDs with this approach, but it worked well. I used a hot air device I ordered from ebay. Because I was paranoid about frying the ICs, I went with a low-temp solder paste. The online videos on SMD soldering often show a "mask" applied to the PCB with the paste wiped over it, deposited on the PCB through critically-placed cutouts. Then the SMD devices placed with tweezers, and the whole assembly heated slowly on a hot plate or in an temperature-time controlled oven. I figured the chances of keeping all the devices lined up with tweezers was 0%. Doing them one at a time with the hot air gun worked very well.

Here's my approach. This is not right or wrong, may aggravate the experts, and your mileage may vary. But it worked for me:
  • I applied a miniscule amount of flux onto each solder pad with a flux pen. Probably not needed, but I love flux.
  • Next a small dot of solder paste was positioned using a plastic toothpick for final positioning. The flux made it slide easily into place. If I squirted out too much flux I could use the fine tip of the toothpick to remove a tiny bit until I got a good size.
  • With all the solder applied to all the pads, I then carefully positioned the SMD chip. I got it as close to perfect as I could visually (a good magnifying visor is critical).
  • Then the hot air gun. Modest air flow setting, and starting at a distance, waving the air supply gently over the chip. Goal is to heat things up slowly (mimicking a pre-heating stage of a hot plate or oven). If the gun gets too close or the air flow too brisk, it will blow the chip out of position. There is a real mental "rush" when the solder suddenly turns from dull grey to that lovely shiny silver. I tried not linger with the air any longer than needed (no fear of "cold-solder" joints!). As the solder melts, surface tension around the drop of solder and the soldering pads pulled the chip into final perfect position.
  • Last critical step is inspection. My first couple of attempts produced some bridging between pads, but re-application of some heat fixed those.
I present this not as a set of recommendations, but rather to ask for comments and critiques. There are folks for more expert than I am at SMD soldering -- do you see anything that I should change? Improve?

I am concerned about heating up completely SMD#1 when I move on to solder its neighbor SMD#2. I won't know until I see the PCBs how much of a problem that might be.

Thoughts?

-Jon
 
It is good to hear back from you.

I continue to try and improve the BOM, but since I don't have my Printed Circuit Boards (PCBs) yet, it is still difficult.

My order from the BOM has arrived, and here's 4 more things that I found:
  1. Line 30, Item 29 of the original BOM calls for 14 resistors but there are only 13 resistors listed
  2. Line 40, Item 31 of the original BOM calls for 18 resistors but there are only 14 resistors listed
  3. Line 44, Item 35 of the original BOM calls for 6 resistors, but there are either 8 or 9 listed (R39 is shown twice)
  4. Line 67, Item 58 of the original BOM -- the Mouser part is a fused IEC receptacle but there is no fuse. A fuse needs to be added to the BOM.
I have passed this information along to Andrew Russell ("bonsai") but have not heard back from him.

These are very minor issues (the resistors) and easy to fix if a few more are needed.

When my PCBs arrive, I am going to put them on a scanner an make PDF's of each one. I like to use diagrams like that to guide my building. I'll send you the PDFs when I make them.

-Jon

P.S. We were in Prague and Cesky Krumlov in 2018 and loved them both!