Temperature fluctuation fix for v2 Units with the newer Melzi boards (v4.3)
This is the “official” Wanhao response for now. If you have erratic temperature swings then this might be the fix for you. The newer boards (labeled v4.3) have a ground plane problem and cause the temperatures to vary greatly when the heater is turned on. If you have a Melzi board with a different version then this may not be the issue. Abdul Abdali was kind enough to put together the following guide that shows how to modify the board to help with the problem.
PDF of the Instructions: TEMP-FLUX-FIX-Rev.-0.011816.pdf