Dating fender power transformers
The next one or two numbers are the month where January is 1 and December is 12. Example: AB763 = second revision, July, 1963 AA1070 = First revision, October, 1970 Misc Dating Info: Silver face amps with the aluminum trimmed grilles are from 67 or 69.The fist Master volume controls were first installed in 72.Serial Number: There is no information readily available for dating Fender amps by serial number but there are people working on it. Circuit Code: In 1963 Fender stoped using model numbers to identify schematics and began using the model name and an assigned circuit number.These circuit numbers which are located on the tube chart can be usefull for getting a rough date on an amp.The raised “Fender” grille logo lost its tail around 76.There are exceptions to this rule like the the Bronco.There are several ways to determine when a Fender amp was produced.
Date Code: Wide panel, narrow panel, brown, blonde, and black face amps have a date code hand-stamped on the tube chart. The first letter translates to the year and the second to the month. Example: FG=July 1956, QA=January 1967, and a reissue CG=July 1992 EIA Source-Date Codes: Electronic components such as transformers, potentiometers, speakers, and some capacitors are often stampted with a date code indicating who manufactured them and when.
If possible, open up the chassis and check a few of the pots’ and capacitors’ manufacturer codes.
Remember, many components could have been changed over the years, speakers blow, caps dry out, transformers melt down, and pots wear out.
The blackface head had a diode recifier, one normal channel and a vibrato channel with no reverb.
The silverface Bandmaster amps got a 5U4GB tube rectifier and the vibrato channel got reverb. Due to this the silverface Bandmaster Reverb is less powerful, has less attack and breaks up earlier than the blackface Bandmaster.