I’ve spent about 6-7 hours tonight working on an idea I have for helping to find the cause of the classic dropouts. It’s tedious but will be worth it later. Here’s the details. I’ve made a map, using a spreadsheet, of the locations of every single component on the main board. That way I can search for the value of a component or for the component identifier itself. This effort’s biggest value is in comparing the first generation P1 board components to the P4 board components. So far the P4 board I’m using is more reliable in that it has shown zero classic dropouts after being operated in the winter and summer without a dropout.

This spreadsheet also will make it easier to find out where the DCN’s were applied. Usually, a DCN’s intention is to improve the operation of a specific circuit. So all of the components that are changed in that circuit would be part of one of the DCN numbers. This is standard engineering practice. If they followed it, then the DCN’s will not be hard to find and then document.

All of this will help identify why one revision of board is less effected by constant use, than another revision.

If you look on your main boards, some of them have decals on them that list 3
DCN numbers. That stands for Design Change Number. One of the 3 numbers is for a
firmware upgrade. The other 2 are for parts changes. This exercise will help me
to understand the even more extensive changes made to the 65kw boards.