Hughes & Kettner “The first H&K guitar amplifier, the AS 64 was built in 1985 and then officially launched in 1986.
Serial number coding system. Since 2005 the manufacturing date is also written on a sticker on the rear panel.
Since 2002 we run an ACCESS data base which helps us to track every serial number back to the date of manufacture. Everybody in our comapony has access to this data base – easy.
For manufacturing dates before 2002 we need to send the serial number to the head of the electronics shop. He has filed all production runs and can track the serial number by run. So this is a bit more hassle, but works, too.” [Source: Martin Reichhart, Hughes & Kettner, email 26/3/2008]

http://en.wikipedia.org/wiki/Hughes_%26_Kettner

Hughes & Kettner Product Manuals http://www.britishaudioservice.com/manuals.shtml

H&K Schematics

http://www.freeinfosociety.com/electronics/schempage.php?cat=1

http://analogguru.an.ohost.de/

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