Lessons learned

[oskar]

Like most of us (I assume), we will make some mistakes or wanted to have done some things differently after finishing the project. So I've descided to publish all my 'mistakes' and advises I got from people who helped me, and hopefully help others who are still starting up or considering to start building their MegaDrum.

I'm busy building/mounting my second PCB due some mistakes, improvements and finally a fatal mistake.

So please feel free to share your lessons learned, it was something I missed on the forum.

Some of the items I will describe under this topic;
- What went wrong in my sequence of the steps to follow, per item
- What did I learn by gathering the right parts and/or how to determine alternative parts/components. (World wide).
- What was my best way of making a PCB, and would I change next time.
- Calculating and assuming my skills and riscs.
- What went wrong by chosing and building my enclosure.
-....

General:
- Forget any time table, unless you are very experienced. Doing things in any rush or under pressure, you will make mistakes. Check and over think every next step and each component you want to solder every hole you're about to drill. If you notice any stress or getting tired, stop immediatly (with soldering for sure)
- Make your own components (check-) and tools list, especially considering that everybody is building their own enclosure choose their own buttons and knobs and deside how jacks are placed. Some wrote they build a MD for about 70 pounds. Maybe they did but then they must have had all the tools.
- Use sockets for all IC s, MUX, Atmega, PIC etc., not only for removal, these components are allergic to statics (fingerprints) etc. When finished soldering just plug in every component, with a tool. Use of a grounding bracelet can be a save way building up a PCB.
- Read this forum carefully and/or search with keywords on any topic. Most questions asked are answered only once. Following this forum for 1 or 2 weeks before I started was very userfull, also for finding ,my way on this entire site, and developing my own ideas for the design and development and puchase of parts for my MD. Thanks to contributions of others, now it's my turn to contribute.

to be continued.

[airflamesred]

Good idea

[oskar]

PCB (52i) (made 2 boards, and had to throw the first one away)

- I Moved all components as far as I could, away from those places where boxed headers should be installed. Otherwise (and I did) I had to drill through the plastic boxes, they are to wide (R27, R26, R13, C10, C1 and some of the bridges).
- For the second (PCB) attempt I used a double sided PCB, so I could draw fat lines for the bridges (red lines on the board design). This was a 50 % succes, next time I won't bother to try this again and just solder red wires as the board design of Dmitri shows.
- Before drilling I used a nail to punch small pits for positioning my drills, also because I drilled out of my hand with a dremel.
- I used 0.8 mm drill for regular holes, 1 mm drill for the headers (incl. boxed) and 5 mm for PCB holders.
- Before putting the PCB into a bath of chemicals I drilled the holes, so it's easy to repair were necessary (due to misdrills) with a permenent marker, before the copper was gone.
- Check all the lines from beginning to the end, before soldering anything onto the board, and repair where necessary. The second board had a terrible quality to start with, as the picture shows I made a few fixes (drilled holes for them). In the future I will only use good quality plates with a smooth surface without any ribbon and/or scratches on the copper.
- I did not save all the ground copper, I think this is not such a problem. Is it? It made me crazy and the risk of soldering any ground to something else is being reduced.

[oskar]

Checklist

A checklist/shopping list is essential to have a total overview for any project. For example the connectors should fit in the enclosure you choose. Don't forget to order a programmed Atmega from Dmitri, otherwise it won't work or be enabled for updates.
If someone wants my list I willing to mail it. I made an Excel sheet with following columns.
- Position (example C1,4,5,9,10,11,13,14) (At least all positions Dmitri mentions in his parts list should occur here)
- Topic lines
- Topic example: Capacitors (example 100nF)
(all Capacitors on the following lines, and then the next topics; Diodes, Resistors, Inductors, IC, IC-sockets, Connectors/headers, Sockets, Cables/wiring, Controls, LCD/LED, Crystals, PCB, Tools/Chemicals etc.)
- Type (LCD example HD44780 compatible)
- Begin stock qty
- Ordered qty
- Received qty
- Necessary qty
- Current Stock (calcution) (I did not add a "used qty" column)
- Price (p.p.)
- Price (total)
- Ordered at (weblink or supplier)
- extra comment
If "Current Stock" +/+ "Ordered qty" < "necessary qty" the "order qty" cel/field turns red automatically.