Hi Bernard,
At first the production line of TDA1541a was in Europe factory.
But on the middle of 199X. The production line was transfered to Taiwan. The outlook different U can see is the the europe type had philips logo & white line on the left side. The Taiwan product had Taiwan on the left side. But someone say that on 1996~1997 the Taiwan re-open the TDA1541A & produce S2 Crown supply to marantz. But nobody can prove for this message.
The OLD TDA1541A Had several grade, TDA1541A is standard, Then R1, N1, the different of old S2 & New S2 easy to see on the difference of the crown. The OLD 1541A Double Crown was select from S1. The line of the selection is 1541A>>>>select>>>S1( print one crown)>>> selectS1 grade>>>>S2(then print the second crown). Due to the two crown was print in different time, There will had a little different.
Hope can help U.
Bernard, the data PDF file show the path of selection already.
The data was from Philips semi-conductor hand Book.
thanks
thomas
www.diyaudiocraft.com