1-65 to 100-65 Power Transformer swap

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Author Message   JR Posted on Monday, April 03, 2006 - 05:16 pm:    I was hoping someone out there might know if this is an easy swap. I know MM stopped using the 1-65 early on and switched most 2275-65s to the 100-65-120 P/T, so when I ordered a replacement, that was all I could get. The wire colors are different on the two, and Andy Turner from Mojotone is out this week, so if anyone can give me some guidence, I'd really appreciate it!   JR Posted on Tuesday, April 04, 2006 - 11:59 am:    Service bulletins to the rescue! Read #3 and 4. Problem solved.   JR Posted on Wednesday, April 05, 2006 - 01:07 am:    Then again, maybe not! I followed the instructions exactly, but when I turn the amp on (hi or low, doesn't matter) nothing happens. With the power switch off and the standby on, the light and tubes light up! If I turn the power switch on and the standby on, my current limiter lights up! Aaaarrrgh! Also, the service bulletin mentions another wire from the transformer, Black/Yellow. The 100-65 I got from Mojo doesn't have it. I figured it didn't matter since the instructions say it is unused, but I thought that was a little strange...   JR Posted on Wednesday, April 05, 2006 - 02:15 pm:    Okay, folks. The amp is finished. For those of you who may have to replace a 1-65 power transformer with a 100-65, service bulletin 4 is definately the bible, BUT the people at Music Man forgot to mention one thing: The standby switch is now the power switch, and standby is now the middle position of the Hi/Off/Low switch on the front panel! Happy tweaking!   Steve Kennedy (admin) Username: admin Registered: 03-2002 Posted on Thursday, April 06, 2006 - 09:38 pm:    What you are describing is the main difference between the AC power configuration of an early 1974-76 amp and the later 1977-80 amps of the same basic model! Steve   Edward Solberg (edward_solberg) Username: edward_solberg Registered: 05-2006 Posted on Friday, September 15, 2006 - 07:49 am:    thanx, JR, your frustration with your new 100-65-120 and the omission in Service Bulletin 4 of the change in switching has saved me many hours of grief as I prepare to begin my own transformer transplant. I too, have been very curious about the "missing" black/yellow wire--I am glad to note that this difference is not important. thanks for the book report on the continued accuracy of the service bulletin from 1978 with a 2006 transformer. ed s